JP4096973B2 - Waveform signal generation method, waveform signal generation apparatus, and recording medium - Google Patents

Description

  The present invention relates to a waveform signal generation method, a waveform signal generation device, and a recording medium that are used in an apparatus for generating a musical sound signal, such as an electronic musical instrument, a mobile phone, an amusement device, and the like. About.

  In an electronic musical instrument, a mobile phone, an amusement device, etc., a musical sound signal is generated via a built-in or external electroacoustic transducer (speaker or the like). Here, the range of sound that can be converted has a predetermined limit. In particular, with regard to bass, only sounds up to the lowest frequency defined by the lowest resonance frequency of the electroacoustic transducer (hereinafter referred to as “the lowest frequency” or “the lowest frequency that can be reproduced”) can be generated. In order to solve this, a technique for generating “pseudo bass” is known. This is a technique using the human illusion that when an audio signal of two frequencies is generated, a signal corresponding to the greatest common divisor of both is heard. For example, in order to generate a “pseudo bass” of 100 Hz by a speaker that cannot output an audio signal of 100 Hz, if two frequencies having a maximum common divisor of 100 Hz, such as “200 Hz and 300 Hz” and “300 Hz and 400 Hz”, are generated. Good.

  For example, Patent Document 1 discloses details of the technology. In this technique, filtering processing is performed on components that cannot be reproduced by a speaker in digital audio signals that are sequentially supplied, and frequency components that are twice, three times,... Of these components are generated. The frequency component generated in this way and the original audio signal are added and sounded through a speaker.

US Pat. No. 5,930,373

However, in the technique of Patent Document 1, since it is necessary to perform processing such as multiplication for each digitally supplied digital audio signal at each sampling period, a large amount of computation is required to generate pseudo bass. Become. In an electronic musical instrument or the like, it is necessary to perform various kinds of processing in addition to the generation of pseudo bass, so that there is a limit to the processing capacity allocated for the generation of pseudo bass.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a waveform signal generation method, a waveform signal generation apparatus, and a recording medium that reduce a processing load necessary for generating pseudo bass.

In order to solve the above problems, the present invention is characterized by having the following configuration. The parentheses are examples.
2. The waveform signal generation method according to claim 1, wherein a sound generation instruction with a specified pitch is generated in the waveform signal generation method for generating a waveform signal of a plurality of sound generation channels in order to generate a musical sound via an electroacoustic transducer. A process of receiving information (note-on event) (step SP2) and a determination process of determining whether the designated pitch is equal to or lower than a predetermined boundary pitch related to the electroacoustic transducer (step SP8) and a first waveform signal for generating a first waveform signal by an algorithm combining a plurality of operators on the condition that it is determined that the designated pitch is not less than or equal to the boundary pitch in the determination process On the condition that the generation process (steps SP10, SP22 to SP26) and that it is determined in the determination process that the designated pitch is less than or equal to the boundary pitch, A second waveform including, as a pseudo bass signal, a plurality of harmonics that are harmonics of the specified pitch and whose harmonics are equal to or greater than the boundary pitch that has the highest common divisor of the specified pitch by an algorithm that combines a plurality of operators. A second waveform signal generation process for generating a signal, wherein the first operator (the modulator-side operator of the modified example (9)) that generates waveform data having the pitch of the specified pitch, and 2 of the specified pitch A second waveform signal for generating the pseudo bass signal by a second operator (the carrier side operator) that performs frequency modulation on the waveform data of double pitch with the waveform data output by the first operator. And a generation process (steps SP12, SP32 to SP38).
In the waveform signal generating device according to claim 2, a waveform signal generating device for generating a waveform signal of a plurality of sound generation channels with a specified pitch in order to generate a musical sound via an electroacoustic transducer. Means for receiving pronunciation instruction information (note-on event) (step SP2), and judging means for judging whether or not the designated pitch is equal to or lower than a predetermined boundary pitch related to the electroacoustic transducer (Step SP8) and a first waveform signal is generated by an algorithm combining a plurality of operators on the condition that the determination means determines that the designated pitch is not less than or equal to the boundary pitch. On condition that the waveform signal generating means (steps SP10, SP22 to SP26) and the determining means determine that the designated pitch is equal to or lower than the boundary pitch. Then, a second harmonic including a plurality of harmonics that are harmonics of the specified pitch and whose harmonics are equal to or higher than the boundary pitch at which the highest common divisor has the specified pitch is obtained as a pseudo bass signal by an algorithm that combines the plurality of operators. Second waveform signal generating means for generating the waveform signal of the first operator (modulator side operator of the modified example (9)) for generating waveform data of the pitch of the specified pitch, and the specified pitch Second pseudo-bass signal is generated by a second operator (carrier side operator) that performs frequency modulation on waveform data having a pitch twice that of the first operator. And waveform signal generating means (steps SP12, SP32 to SP38).
The recording medium according to claim 3 stores a program for causing a processing apparatus to execute the method according to claim 1.

  Thus, according to the present invention, the first or second waveform signal is generated by determining whether or not the designated pitch is equal to or lower than a predetermined boundary pitch related to the electroacoustic transducer. Therefore, it is possible to generate a pseudo bass while reducing a necessary calculation amount.

1． First embodiment
1.1. Principle of the embodiment
1.1.1. Waveform Component Analysis In the present embodiment, the musical sound waveform is stored separately as “periodic component” and “noise component”, and details thereof will be described. When the musical sound waveform of a natural musical instrument is subjected to FFT (Fast Fourier Transform) analysis, the frequency component of the musical sound waveform can be separated into a frequency component that is continuous on the time axis and a frequency component that is intermittent on the time axis. When a waveform is synthesized based on the former frequency component, a “sound component” of a musical tone waveform is obtained, and when a waveform is synthesized based on the latter frequency component, a “noise component” of a musical tone waveform is obtained. An example is shown in FIG. FIG. 4A shows a musical sound waveform (original waveform) of a saxophone. FIG. 4B shows the periodic component, and FIG. 4C shows the noise component. As can be seen from these figures, the noise component often has a short section with a large amplitude level and is often distributed over a wider frequency range than the periodic component of the musical sound signal. For this reason, it is rare that the characteristics of the electroacoustic transducer become a problem, and it can be understood that only the periodic component needs to generate a pseudo bass as necessary.

1.1.2. Equal loudness curve In human auditory sense, even if the sound pressure level is constant, it seems that the volume feeling is different if the frequency is different. Therefore, when the curve of the sound pressure level with equal sound volume (loudness) is drawn on the graph with the horizontal axis representing the frequency and the vertical axis representing the sound pressure level, it is shown in FIGS. 5 (a) and 5 (b). Such characteristics can be obtained. These characteristics are called “equal loudness curves”. Figure (a) is called "Fletcher &Manson's equal loudness curve" and is a little old. The figure (b) is called “Robinson &Dudson's equal loudness curve”, which is relatively new and adopted in ISO.

1.2. Hardware Configuration of Embodiment Next, the hardware configuration of the musical tone synthesis system according to the first embodiment of the present invention will be described with reference to FIG. The hardware of this embodiment is constituted by a general-purpose personal computer. In the figure, reference numeral 2 denotes a hard disk which stores an operating system, an application program for a musical tone synthesis system, waveform data, and other various data. Reference numeral 4 denotes a removable disk such as a CD-ROM or DVD-RAM, which stores the same information as the hard disk 2. Reference numeral 6 denotes a display that displays various information to the user. Reference numeral 8 denotes an input device, which includes a keyboard, a mouse, a keyboard, and the like, and various information is input by the user. A sound board 10 includes a waveform memory sound source that generates a musical sound signal based on supplied performance information and an AD converter that samples an analog signal input from the outside. The musical sound signal generated by the sound source in the sound board 10 is generated via the sound system 12. The sound system 12 includes an amplifier and an electroacoustic transducer. As the electroacoustic transducer, a speaker or headphones can be selected, and these have different conversion characteristics. Reference numeral 16 denotes a MIDI interface which exchanges MIDI signals with an external MIDI device. A timer 18 generates an interrupt request every predetermined time. Reference numeral 20 denotes a CPU which controls each unit in the musical tone synthesis system via the bus 14 based on a control program which will be described later. A ROM 22 stores an initial program loader and the like. A RAM 24 is used as a work memory for the CPU 20.

1.3. Operation of the embodiment
1.3.1. Waveform Data Creation Processing After the operating system is started up on the personal computer and the application program of the waveform analysis / synthesis system is started up, the user performs a predetermined operation to execute the waveform data creation processing. Details of the processing will be described with reference to FIG. The figure shows the contents of the processing program executed in the CPU 20 in a functional block diagram. In the figure, reference numeral 30 denotes material waveform data such as a recording waveform of a musical instrument's musical sound, which is input from the outside via the sound board 10 or the removable disk 4 or the like. Reference numeral 40 denotes a waveform analysis unit, which classifies the frequency components of the material waveform data 30 into components that are continuous on the time axis (deterministic frequency components) and other cut-off components (noise components). Details of the waveform analysis unit 40 will be described with reference to FIG. Inside the waveform analysis unit 40, 42 is an FFT analysis processing unit, which performs FFT analysis processing on the material waveform data 30. Here, first, a window function having a length eight times the pitch period is applied to the material waveform data 30, and a frequency component within the range of the window function is analyzed.

  Next, the position of the window function is shifted backward by 1/8 of the pitch period on the time axis, and the frequency component is similarly analyzed. When this process is repeated for the entire original waveform data, a change in frequency component on the time axis is obtained. A continuous component separation unit 44 separates components that are continuous on the time axis from a series of frequency components. The separated component is output as a deterministic frequency component 32 and supplied to the synthesis unit 46. In the synthesizer 46, deterministic waveform data is synthesized based on the deterministic frequency component 32. A subtracting unit 48 subtracts deterministic waveform data from the material waveform data 30. This subtraction result is output as noise component waveform data 34.

  Returning to FIG. 3, reference numeral 54 denotes attack and loop information, which is set by the user with reference to the material waveform data 30. Or you may make it set automatically using the result of the said waveform analysis, etc. according to a user's specification. The contents of the attack & loop information 54 are the length of the attack portion that is read only once at the beginning of waveform reproduction, the length of the loop portion that is repeatedly read after that, and the like. Reference numeral 36 denotes a waveform synthesizer, which synthesizes the waveform data of the attack part and the loop part based on the deterministic frequency component 32, the noise component waveform data 34, and the attack & loop information 54. The synthesized waveform data is stored as normal musical sound waveform data 38 in the hard disk 2 or the like. Here, an outline of synthesis processing in the waveform synthesis unit 36 will be described. First, from the attack & loop information 54, an attack start address indicating the head of the attack portion, a loop start address indicating the head and end of the loop portion, and a loop end address are determined.

  Next, among the deterministic frequency components of the loop part, a component that is close to the phase of the loop start at the loop end is selected, and for the selected component, the phase at the loop end matches the phase at the loop start. It is corrected to. When the loop is a long group (the loop size is several hundred milliseconds or more), a component that is not a value close to the phase of the loop start at the loop end (an anharmonic component) may be selected and corrected. Next, sine wave synthesis is performed based on the corrected frequency component, and waveform data of the loop portion is generated. Next, the deterministic frequency component of the attack part that is not used in the loop part is processed so that it gradually fades out from the middle of the attack part to the end of the attack part, and the processed deterministic frequency Sine wave synthesis is performed based on the components, and waveform data of the attack part is generated. Further, while the volume of the noise component waveform data 34 is controlled, this is mixed into the attack part and the loop part. The waveform data of the attack part and the loop part created as described above is a waveform that is very similar to the material waveform data 30, and has a good connection from the attack part to the loop part and from the loop end to the loop start. Become data.

  Next, 60 is a pseudo bass synthesizing unit that generates pseudo bass waveform data 52 based on the lowest frequency data 50 indicating the lowest frequency of the sound system 12, the deterministic frequency component 32, and the attack and loop information 54. To do. Here, the minimum frequency data 50 may be one or a plurality of preset frequencies, or may be a frequency that can be arbitrarily set by a user using an operator. In the pseudo bass synthesizing unit 60, an extraction unit 67 extracts a frequency component equal to or lower than the lowest frequency from the deterministic frequency component 32. A harmonic generation unit 62 generates a plurality of harmonic components exceeding the lowest frequency for each extracted frequency component. Here, the frequency of the extracted frequency component varies with time, and therefore the frequency of the generated harmonic component also varies accordingly. For example, if the lowest frequency is 120 Hz, harmonic components at least twice and three times as high as the frequency components of 60 <f ≦ 120 Hz in the deterministic frequency component 32 are generated. Similarly, at least 3 times and 4 times higher harmonic components for frequency components of 40 <f ≦ 60 Hz, and at least 4 times and 5 times higher harmonic components for frequency components of 30 <f ≦ 40 Hz. Will be generated.

  Next, 68 is an envelope conversion unit, which outputs the envelope of each harmonic component so that the volume feeling (loudness) of the pseudo bass generated by each harmonic component matches the volume feeling of the original frequency component. The contents will be described with reference to FIG. According to the equal loudness curves previously shown in FIGS. 5A and 5B, in order to generate the same volume feeling in the low frequency range (for example, 100 Hz) in the harmonic components (for example, 200 Hz and 300 Hz). It is understood that the level of the harmonic component must be reduced and the level change width must be increased. Therefore, in the envelope conversion unit 68, when the envelope level of the extracted original frequency component is the one shown in the characteristic A in FIG. 7, this is converted into the harmonic B by converting it into the characteristic B in FIG. Output as the envelope level of the wave component. In the low sound range of the equal loudness curves of FIGS. 5A and 5B, the sound pressure level of the equal loudness decreases by 10 to 15 dB every time the frequency is doubled. Accordingly, the level L1 in FIG. 7 is set to “10-15 dB × multiplier number”. In addition, the magnitude of the change in the sound pressure level at which the changes in loudness are equal is about 1.4 times in “Fletcher & Manson” and 1 in “Robinson & Dudson” every time the frequency is doubled. About 1 time. Accordingly, the level ratio L3 / L2 in the figure is set to about “1.1 to 1.4 × multiplier number”.

  Returning to FIG. 3, reference numeral 64 denotes an amplitude control unit that multiplies each harmonic component output from the harmonic generation unit 62 by the envelope level output from the envelope conversion unit 68. Reference numeral 66 denotes a plural waveform mixing unit that mixes each harmonic component to which the envelope is applied. This mixing result is stored in the hard disk 2 as pseudo low sound waveform data 52. When the user performs a predetermined operation, the normal musical sound waveform data 38 and the corresponding pseudo low sound waveform data 52 created as described above are transferred to the waveform memory in the sound board 10 as waveform data of a user-defined tone color. The

  By the way, in general, in a waveform memory sound source, different normal musical sound waveform data 38 is stored for each tone range of each tone color (the waveform data may be shared between tone colors and between tone ranges). In this embodiment, among the normal musical sound waveform data, only the pseudo musical sound waveform data corresponding to the normal musical sound waveform data used for the musical sound generation at the pitch where the fundamental wave component of the deterministic frequency component included is not more than the lowest frequency. 52 is stored in the waveform memory. Basically, the normal musical sound waveform data 38 may be stored in one-to-one correspondence, but this is not necessarily required. In some cases, a plurality of pseudo low sound waveform data may be stored for one normal musical sound waveform data, or conversely, one pseudo low sound waveform data may be stored corresponding to a plurality of normal musical sound waveform data. Good. The normal musical sound waveform data 38 stored in the waveform memory is read at a speed based on the F number when a musical sound signal is formed, thereby realizing a desired pitch. As a result, in this embodiment, the frequency component of the normal musical sound waveform data 38 that cannot be actually reproduced due to the ability of the sound system 12 changes according to the F number. Therefore, in this embodiment, a plurality of types of pseudo low sound waveform data 52 are generated for each sound range.

  For this reason, in this embodiment, the sound range to which one pseudo low sound waveform data 52 is applied is narrower than the sound range to which one normal musical sound waveform data 38 is applied, and the number of pseudo low sound waveform data 52 is large. It tends to be. However, the memory area occupied by the pseudo low sound waveform data 52 can be made extremely small as compared with the normal musical sound waveform data 38 by suppressing the sampling frequency. The reason for this will be explained.

  First, in general consumer equipment, the sampling frequency of the musical sound waveform is about 32 to 48 kHz, because the upper limit of the reproduction frequency is set to about 15 to 20 kHz. On the other hand, in the pseudo low sound waveform data 52 (although it differs depending on the minimum frequency data 50), since the upper limit of the reproduction frequency is about 2 kHz, it is sufficient to secure the sampling frequency of about 5 to 10 kHz. For this reason, the data amount of one pseudo low sound waveform data 52 can be suppressed to a fraction of 1 to several tenths of one normal musical sound waveform data 38. In addition, when applying such a low sampling frequency, it is preferable to employ highly accurate inter-sample point interpolation such as “8-point interpolation”.

1.3.2. Waveform synthesis processing After the waveform data is created as described above, when a MIDI event is input via the input device 8 or the MIDI interface 16, the waveform memory sound source in the sound board 10 is controlled based on the MIDI event. A musical sound waveform is synthesized in the sound source. Also, when playing back an SMF (standard MIDI format) file supplied via the removable disk 4 or the like, a musical sound waveform is synthesized based on the event information. The contents of the sound source control process will be described with reference to FIG.

(1) When the pseudo bass effect is off First, when a note-on event occurs, a note-on event processing routine shown in FIG. In the figure, when the process proceeds to step SP2, the part number is substituted for the variable PT, the note number is substituted for the variable NN, and the velocity is substituted for the variable VEL. Next, when the process proceeds to step SP4, it is determined whether or not the flag PLE is “1”. The flag PLE is a flag indicating the on / off state of the pseudo bass effect, where “1” indicates on and “0” indicates off. Note that the value of the flag PLE can be switched at any time by the user performing a predetermined operation.

  If the flag PLE is “0”, “NO” is determined here, and the process proceeds to step SP10. Here, the normal sound generation control subroutine shown in FIG. In the figure, when the process proceeds to step SP22, a sound generation channel for one channel is assigned to the sound source in the sound board 10. The channel number of the assigned sound generation channel is set to a1.

  Next, when the process proceeds to step SP24, musical tone parameters corresponding to the tone color TC (PT) corresponding to the part number PT, the note number NN, and the velocity VEL are set for the channel number a1 in the sound source. Is done. Here, the musical sound parameters include the following.

(i) Address information of normal musical sound waveform data 38 (selected waveform data) corresponding to the note number NN among a plurality of normal musical sound waveform data 38 corresponding to the tone color TC (PT) stored in the waveform memory. Since the musical sound waveform data 38 is generally composed of an attack part and a loop part, it is necessary to set these start and end addresses. However, depending on the tone color TC (PT), the normal musical sound waveform data 38 may be composed only of the loop portion or only one-shot waveform data. Further, different waveform data may be applied for each velocity VEL range.

(ii) F number corresponding to note number NN In the normal musical sound waveform data 38, an original pitch OP is defined for each waveform data. When the note number NN is designated, the progress speed of the read address of the normal musical sound waveform data 38, that is, the difference between the original pitch OP of the selected waveform data and the note number NN and the sampling frequency of the waveform data, that is, The F number is determined.

(iii) Volume envelope parameter When the timbre TC (PT), velocity VEL, and note number NN are designated, the volume envelope parameter for designating the volume envelope is determined in accordance with them.
(iv) Other parameters In addition, a timbre filter parameter corresponding to the timbre TC (PT), note number NN, velocity VEL, pitch modulation parameter, amplitude modulation parameter, and the like are appropriately set.

  Next, when the process proceeds to step SP26, a sound generation start is instructed for the channel number a1 of the sound source. Thus, the process for the note-on event is completed. Thereafter, in the sound source of the sound board 10, the normal musical sound waveform data 38 is read at a speed corresponding to the note number NN, and further, the filter processing corresponding to the timbre filter parameter and the volume corresponding to the volume envelope parameter. A time change process is performed, and a tone signal related to the channel number a1 is sequentially generated without including the pseudo bass. The musical tone signal is generated via the sound system 12. Even if the musical sound signal includes a frequency component equal to or lower than the lowest frequency, the component is not reproduced by the sound system 12, and the user cannot hear it.

(2) When the pseudo bass effect is on When the pseudo bass effect is on (flag PLE = 1) and a note-on event occurs, the process proceeds to step SP6 via steps SP2 and SP4. Here, based on the timbre TC (PT) and the note number NN, it is determined whether or not a pseudo low sound waveform should be generated, that is, whether or not there is a low frequency range component that cannot be reproduced by the sound system 12. Even if the note number NN is specified, the fundamental frequency may be shifted in octave units depending on the timbre, so the determination is made taking into account the timbre TC (PT).

  For example, assume that the lowest reproducible frequency is 120 Hz and the note number corresponds to the fundamental frequency as it is (when there is no octave shift). Here, if the reference pitch is A4 = 440 Hz, A2 = 110 Hz, A # 2 = 116.54 Hz, and B2 = 123.471 Hz. Therefore, a pseudo low sound waveform should be generated when the pitch is A # 2 or less. I understand that there is.

  Next, when the process proceeds to step SP8, the process branches according to the determination result of step SP6. First, if it is determined that “the pseudo low sound waveform should not be generated (note number is B2 or higher)”, the process proceeds to step SP10. As a result, the normal sound generation control subroutine (FIG. 2B) is called as in the case where the pseudo bass effect is off. Accordingly, a tone generation channel for one channel is assigned to the note-on event, and a tone signal based on the normal tone waveform data 38 is sequentially generated in the tone generation channel.

  On the other hand, if “YES” is determined in step SP8, the process proceeds to step SP12. Here, the pseudo-bass tone generation control routine shown in FIG. 8 is called. In the figure, when the process proceeds to step SP32, two sound generation channels are assigned to the sound source in the sound board 10. The channel numbers of the assigned sound generation channels are a1 and a2.

  Next, when the process proceeds to step SP34, musical tone parameters corresponding to the tone color TC (PT) corresponding to the part number PT, the note number NN, and the velocity VEL are set for the channel number a1 in the sound source. Is done. The processing contents are the same as in step SP24 described above. Next, when the processing proceeds to step SP36, a pseudo bass parameter is set in the channel number a2 corresponding to the musical sound signal generated in the channel number a1.

Here, the following tone parameters are set for the pseudo bass.
(i) Address information of pseudo low tone waveform data 52 (selected pseudo low tone waveform data) corresponding to the normal musical tone waveform data 38 selected in step SP34.
(ii) F number of the pseudo low sound waveform data 52 corresponding to the note number NN.
The F number for the pseudo low sound waveform data 52 is also determined by the same procedure as the F number of the normal musical sound waveform data 38. That is, the F number of the pseudo low sound waveform data is determined according to the difference between the original pitch OP of the pseudo low sound waveform data and the note number and the sampling frequency of the pseudo low sound waveform data. Here, the original pitch OP of the pseudo low sound waveform data has the same value as the original pitch OP of the corresponding normal musical sound waveform data (waveform data reproduced by the channel number a1). Therefore, the F number of the pseudo low sound waveform data has a predetermined proportional relationship with the F number of the normal musical sound waveform data (however, the sampling frequencies are different from each other). As a result, in channel number a2, a pseudo bass sound in which the pitch and the time axis are completely synchronized with the musical sound signal generated in channel number a1 is obtained.

(iii) Pseudo Bass Volume Envelope Corresponding to the Volume Envelope of Channel Number a1 As described with reference to FIG. 7, the pseudo bass volume envelope (characteristic B) is different from the volume envelope (characteristic A) of the original waveform. Accordingly, a volume envelope for pseudo bass is set by modifying the volume envelope of channel number a1.
However, in both the normal musical sound waveform data 38 and the pseudo low sound waveform data 52, waveform data whose volume envelope changes is stored in the attack portion of the attack portion and the loop portion, respectively. Therefore, in each channel of the waveform memory sound source, it is not necessary to give a temporal change in volume for the attack portion, and a volume envelope parameter for designating a flat volume envelope of the attack portion is set. FIG. 9 shows a volume envelope (characteristic A ′) for the normal musical sound waveform data 38 given by the channel number a1 and a volume envelope (characteristic B ′) for the pseudo low sound waveform data 52 given by the channel number a2. Here is an example.

Each volume envelope follows the relationship of the equal loudness described with reference to FIG. 7, and starts changing when the waveform data reproduced in each channel enters the loop portion from the attack portion. In the flat portion, the loudness of the frequency component equal to or lower than the lowest frequency included in the reproduced normal musical sound waveform data 38 and the loudness of the pseudo low sound waveform data are substantially matched. Therefore, the level of the characteristic B ′ is higher than that of the characteristic A ′. It is set to be low. Also, in the loop portion, the characteristic B ′ is used to substantially match the loudness change amount of the component below the lowest frequency included in the loop portion of the normal musical sound waveform data to be reproduced and the loudness change amount of the loop portion of the pseudo low sound waveform data. Is set to be steeper than the slope of the characteristic A ′. As a result, in channel number a2, a pseudo low sound waveform in which the loudness characteristic follows a component having a frequency equal to or lower than the lowest frequency included in the musical tone signal generated in channel number a1 is obtained.
(iv) Other parameters The contents of other various parameters are basically set in the same manner as the channel number a1.

  Returning to FIG. 8, when the process proceeds to step SP38, the sound generation start is instructed to the channel numbers a1 and a2 in the sound source. Thus, the process for the note-on event is completed. Thereafter, in the channel number a1 of the sound source of the sound board 10, the normal musical sound waveform data 38 is read at a speed corresponding to the note number NN, and the musical sound signal related to the channel number a1 is sequentially generated without including the pseudo bass. The In synchronization with this, in the channel number a2, the pseudo low sound waveform data 52 corresponding to the note number NN is read, and pseudo bass signals are sequentially generated. As a result, both signals are generated via the sound system 12. The sound system 12 does not reproduce the component below the lowest frequency of the musical sound signal, but the user can listen to the pseudo bass corresponding to the component instead of the component not reproduced, and whether the component is reproduced. The illusion.

  As described above, according to the present embodiment, the volume envelope for the normal musical sound waveform and the volume envelope for the pseudo-low sound waveform can be individually controlled, so that the volume level and dynamics according to the equal loudness curve according to the situation at that time. It is possible to control the range.

2． Second Embodiment Next, a second embodiment of the present invention will be described. The hardware configuration of the second embodiment is the same as that of the first embodiment, but the waveform data prepared in the waveform memory of the sound board 10 and the software configuration for control are slightly different compared to the first embodiment. Only the differences will be described.

(1) Waveform Data Creation Processing In this embodiment, waveform data creation processing similar to that described with reference to FIGS. 3 and 4 is executed, and normal musical tone waveform data 38 and pseudo low tone waveform data 52 are obtained. Further, in the present embodiment, the processing shown in FIG. 10 is executed. In the figure, reference numerals 72 and 74 denote amplitude control units, which control the amplitude of the waveform data 38 and 52. That is, the amplitude of both waveform data is set so that a level difference corresponding to the difference between the attack portions of the characteristics A ′ and B ′ in FIG. 9 of the first embodiment is given to the envelope of both waveform data. A mixing unit 76 mixes both waveform data whose amplitudes are controlled, and outputs the result as pseudo-low tone waveform data 78. These waveform data 38 and 78 are stored in the hard disk 2 and the waveform data 52 is deleted. In this way, the normal musical sound waveform data 38 and the pseudo low sound waveform data 52 corresponding to the frequency component below the lowest frequency included in the normal musical sound waveform data 38, the pseudo low sound waveform data whose amplitude is controlled so as to be equal to the frequency component are obtained. Mixed and pseudo low-pitched waveform data 78 was prepared.

  Here, among the contents described with reference to FIG. 7, the sound pressure level is attenuated to align the loudness of the pseudo bass, but the control of the change in the sound pressure level to align the loudness change is performed. Absent. This is because in “Robinson & Dudson”, since the ratio of the magnitudes of the changes in the sound pressure level is close to 1, it is determined that it can be omitted. The created normal musical sound waveform data 38 and the corresponding pseudo bass sound waveform data 78 are transferred to the waveform memory in the sound board 10 in accordance with a user's predetermined operation. The waveform memory in the sound board 10 stores normal musical sound waveform data 38 for each tone range, but the pseudo-bass waveform data is used for generating musical sounds at a pitch whose fundamental component is below the lowest frequency. It is sufficient to prepare only the normal musical sound waveform data 38 to be stored in the waveform memory.

(2) Note-on event processing Also in this embodiment, when a note-on event occurs, the note-on event processing routine shown in FIG. 2A is started as in the first embodiment. The processing of step SP10 executed when the pseudo bass effect is off, or when the pseudo bass effect is on and there is no low frequency component that cannot be reproduced in the generated tone signal, is completely the same as in the first embodiment. The same. When the pseudo bass effect is on and the musical tone signal to be generated includes a low frequency range component that cannot be reproduced, in step S12, the tone generation control routine with pseudo bass shown in FIG. 11 is called instead of the processing of FIG. It is.

  Steps SP42, SP44, and SP46 executed in this routine are the same as the contents of steps SP22, SP24, and SP26 (FIG. 2B) executed for the normal musical sound waveform. However, in step SP44, instead of the normal musical sound waveform data 38, address information, F number, volume envelope parameter, and other parameters for the pseudo bass waveform data 78 are set as the sound source in the sound board 10. The set address information is a pseudo bass waveform corresponding to the normal musical sound waveform data 38 corresponding to the note number NN among the plurality of normal musical sound waveform data 38 corresponding to the tone color TC (PT) stored in the waveform memory. This is address information of data 78. The F number, volume envelope parameter, and other parameters may basically be the same values as the corresponding parameters of the normal musical sound waveform data 38.

  As a result, when the start of sound generation is instructed for the channel number a1 of the sound source in step SP46, the sound source of the sound board 10 reads the pseudo bass waveform data 78 at a speed corresponding to the note number NN. Further, the tone signal corresponding to the channel number a1 is sequentially generated in a state including the pseudo bass by performing the filtering process according to the timbre filter parameter and the time change process of the volume according to the volume envelope parameter. . The musical tone signal is generated via the sound system 12. Since this musical tone signal includes a pseudo bass corresponding to a frequency component below the lowest frequency that cannot be reproduced, the user can hear it as if the frequency component is being reproduced.

  According to the present embodiment, even when a pseudo bass is generated, the sound generation channel assigned to one note-on event can be suppressed to one channel. For this reason, it is particularly suitable when it is desired to suppress an increase in the number of sound generation channels.

3． Third Embodiment Next, a third embodiment of the present invention will be described. The hardware configuration of the third embodiment is the same as that of the first embodiment except that the sound source of the sound board 10 is not a waveform memory sound source but a frequency modulation sound source (FM sound source). Although the software configuration is slightly different from that of the first embodiment, only the difference will be described below.

(1) Waveform data creation processing In this embodiment, the musical tone signal is generated by the FM sound source method, and therefore the waveform data creation processing as in the first and second embodiments is not executed.

(2) Normal sound generation control in note-on event processing Also in this embodiment, when a note-on event occurs, a note-on event processing routine shown in FIG. 2A is started as in the first embodiment. However, in this embodiment, when a pseudo bass sound should not be generated, the normal sound generation control subroutine shown in FIG. 12A is called in step SP10. When the process proceeds to step SP52 in FIG. 12A, a sound generation channel for one channel is assigned to the sound source in the sound board 10. The channel number of the assigned sound generation channel is set to a1.

  Next, when the process proceeds to step SP54, the tone signal TC (PT) corresponding to the part number PT, the note number NN, and the velocity VEL are used for the channel number a1 in the sound source. Music parameters are set. In general, the tone parameters of the FM tone generator set for the tone generator channel are based on tone color data prepared for each tone color TC, and the note number NN and the basic tone parameter for tone signals. It is prepared by adding correction (scaling) according to the velocity VEL. Here, the musical sound parameters include the following.

(i) Algorithm In the FM sound source method employed in this embodiment, an algorithm (connection state of n operators) is selected according to the tone color TC (PT). Also, the type of waveform data used by each operator (sine wave, half-wave rectified waveform of sine wave, full-wave rectified waveform of sine wave, etc.), and the speed of progression of phase data for generating the waveform data are controlled. Pitch data (controls the pitch of the waveform data), a multiplier for the pitch data for each operator (the speed of the phase data in each operator is controlled by the product of the multiplier and the pitch data), low frequency modulation control data (vibrato) The envelope parameters for controlling the envelope waveform applied to the waveform data generated by each operator are determined according to the tone color TC (PT), the note number NN, and the velocity VEL. As the contents of the algorithm, various kinds of contents can be considered, but as a simple example, as shown in FIG. 13 (a), “n = 2” operators OP1 and OP2 are connected in series. It is done.

(ii) Volume envelope parameter The volume envelope of the tone signal output from the FM sound source corresponds to the envelope given to the operator (OP2 in the illustrated example) at the final stage of the algorithm. As described above, the envelope parameter of the envelope is determined according to the tone color TC (PT), the note number NN, and the velocity VEL.

(iii) Other parameters When filtering is performed on the output of the algorithm, timbre filter parameters corresponding to the timbre TC (PT), note number NN, velocity VEL, and the like are set. Furthermore, a pitch envelope parameter for controlling a pitch envelope for changing the pitch of the generated tone signal may be set.

  Next, when the process proceeds to step SP56, the sound generation start is instructed to the channel number a1 of the sound source. Thus, the process for the note-on event is completed. Thereafter, in the sound source of the sound board 10, the tone signal related to the channel number a1 is sequentially generated without including the pseudo bass. The musical tone signal is generated via the sound system 12. Even if the musical sound signal includes a frequency component equal to or lower than the lowest frequency, the component is not reproduced by the sound system 12, and the user cannot hear it.

(3) Sound generation control with pseudo-bass in note-on event processing When the process proceeds to step SP12 in the note-on event processing routine (FIG. 2 (a)), the sound generation control routine with pseudo-bass shown in FIG. 12 (b) is called. . In the figure, when the process proceeds to step SP62 in the figure, sound generation channels for two channels are assigned to the sound source in the sound board 10. The channel numbers of the assigned sound generation channels are a1 and a2.

  Next, when the process proceeds to step SP64, the tone signal TC (PT) corresponding to the part number PT, the note number NN, and the velocity signal VEL corresponding to the channel number a1 in the sound source are processed. Music parameters are set. The processing content is the same as in step SP54 described above. Next, when the process proceeds to step SP66, m operators for pseudo bass are secured in the channel number a2 corresponding to the musical tone signal generated in the channel number a1, and these parameters are set.

Here, the following tone parameters are set for the pseudo bass.
(i) Algorithm In order to generate a pseudo bass sound, an algorithm having a configuration in which two operators OP3 and OP4 are connected in parallel is set for channel number 2 (see FIG. 13B).
The frequency component of the musical sound signal generated in the channel number a1 includes a frequency component corresponding to the note number NN that is not reproduced by the sound system 12. Here, it is assumed that the operator at the last stage of the channel number a1 and the operator whose pitch data is 1 generates the lowest sound of the channel. In that case, the channel number a2 is set with the pitch data of the frequency f corresponding to the note number NN as with the channel number a1, and further, the harmonics of the frequency f are set by appropriately setting the multipliers for each operator of the channel number a2. Generate overtones. In each operator, a combination of a plurality of multipliers (for example, “2, 3”, “3,4”,...) Such that the pitch of the waveform data to be generated is greater than the lowest frequency and the greatest common divisor is “1”. ...) Is set, and the pitch frequency of the actually generated signal becomes “2f, 3f”, “3f, 4f”,.

(ii) Volume envelope parameter When the timbre TC (PT), velocity VEL and note number NN are specified, in order to specify the volume envelope to be given to the pseudo bass operator (OP3, OP4 in the illustrated example) A volume envelope parameter is determined. The relationship between the volume envelopes of both channel numbers a1 and a2 is the same as in the first and second embodiments. That is, the envelope parameters of the volume envelope having the same loudness relationship as the volume envelope of the low frequency component not reproduced included in the musical tone signal generated in the channel a1 are set in the two operators of the channel number a2. Here, the envelope parameters set for each operator are different from each other according to the pitch of the waveform data to be generated.

(iii) Other parameters In addition, a tone color filter parameter corresponding to the note number NN and velocity VEL is set. When the pitch envelope is set for the channel number a1, by setting the same pitch envelope for the channel number a2, a pseudo bass pitch generated by the channel number a2 is generated by the channel number a1. It is possible to follow the pitch variation of the musical sound signal. Here, the tone parameter for the pseudo bass described above can be created in the same manner as the tone parameter for the tone signal. Specifically, first, the tone color data prepared for each tone color TC includes pseudo bass data. Then, correction (scaling) according to the note number NN and velocity VEL is applied to the basic musical sound parameter for pseudo bass included in the tone color data, thereby creating a musical parameter for pseudo bass.

  Returning to FIG. 12B, when the process proceeds to step SP58, the start of sound generation is instructed to the channel numbers a1 and a2 in the sound source. Thus, the process for the note-on event is completed. Thereafter, in the channel number a1 of the sound source of the sound board 10, musical tone signals are sequentially generated without including pseudo bass. In synchronization with this, a pseudo bass signal corresponding to the note number NN is sequentially generated in the channel number a2. When both signals are sounded through the sound system 12, the user is not able to reproduce the sound signal of the channel number a1 due to the pseudo bass sound of the channel number a2 even though the frequency component below the lowest frequency is not reproduced. An illusion that the frequency component is heard.

Four. Fourth Embodiment Next, a fourth embodiment of the present invention will be described. Although the hardware configuration of the fourth embodiment is the same as that of the third embodiment, the software configuration is slightly different from that of the third embodiment, so only the differences will be described.

(1) Sound generation control with pseudo-bass in note-on event processing In this embodiment, when processing proceeds to step SP12 in the note-on event processing routine (FIG. 2 (a)), pseudo-bass with sound shown in FIG. The pronunciation control routine is called. In the figure, when the process proceeds to step SP72 in the figure, a sound generation channel for one channel is assigned to the sound source in the sound board 10. The channel number of the assigned sound generation channel is set to a1.

  Next, when the process proceeds to step SP74, an operator (m + n) is secured for the channel number a1 in the sound source. Here, in this embodiment, it is assumed that an FM sound source that can change the number of operators for each channel is used. “M” and “n” are the numbers of operators for normal tone generation and pseudo bass in the third embodiment. Next, musical tone parameters corresponding to the tone color TC (PT) corresponding to the part number PT, the note number NN, and the velocity VEL are set. The algorithm set here is equivalent to the algorithm for normal tone generation in the third embodiment and the pseudo bass algorithm connected in parallel. An example of this is shown in FIG. The other musical tone parameter settings are the same as in the third embodiment. Next, when the process proceeds to step SP76, the sound generation start is instructed to the channel number a1 in the sound source. Thus, the process for the note-on event is completed. Thereafter, in the channel number a1 of the sound source of the sound board 10, musical tone signals including pseudo bass are sequentially generated.

  As described above, the difference between the third and fourth embodiments is whether to secure two sound channels or one channel when performing sound control with pseudo-bass. Which embodiment is selected may be determined based on whether the maximum number of operators per channel is “n + m” or more. In the example of FIG. 13, if the maximum number of operators is “3”, the configuration of the third embodiment ((a) + (b) in FIG. 13) must be adopted. Further, any embodiment can be adopted as long as the maximum number of operators is “4” or more, but it is more advantageous to adopt the fourth embodiment in that the number of channels can be suppressed.

Five. Modifications The present invention is not limited to the above-described embodiments, and various modifications can be made as follows, for example.
(1) In the above embodiments, a musical tone synthesis system is realized by software running on a personal computer, but similar functions are used for various electronic musical instruments, mobile phones, amusement devices, and other devices that generate musical sounds. May be. In addition, the software used in the above embodiments can be stored in a recording medium such as a CD-ROM or a flexible disk and distributed, or can be distributed through a transmission path.

(2) In the above embodiment, a high pass filter that attenuates a frequency component below the lowest frequency that can be reproduced by the sound system is interposed between the sound board 10 and the sound system 12, and a frequency below the lowest frequency that can be reproduced. Ingredients may be cut. Thereby, the power consumption of the amplifier in the sound system 12 can be reduced.

(3) When the sound board 10 is a PCM sound source having a waveform RAM, a pseudo low sound waveform may be generated by analyzing existing waveform data. At this time, the lowest frequency that can be reproduced by the user may be selected or designated, and the pseudo low sound waveform data may be automatically created based on the lowest frequency selected or designated.

(4) When the present invention is applied to an electronic musical instrument, if it is incorporated into an electronic musical instrument equipped with a sound system, it is preferable if a maker side sets in advance a pseudo bass effect that matches the sound system. Even in such a case, a plurality of settings may be prepared on the manufacturer side so that the user can select a desired setting from the settings. On the other hand, in the case of an electronic musical instrument (such as a synthesizer) or a sound board for a personal computer that does not include a sound system, it is impossible to specify the sound system in advance. In this case, similarly to the above embodiment, the minimum frequency, attenuation amount, amplitude compression amount, etc. of the pseudo bass effect may be set by a personal computer equipped with an electronic musical instrument panel or sound board.

(5) In the above embodiment, as parameters for generating the pseudo bass, the minimum frequency, the attenuation (level L1 in FIG. 7), and the amplitude compression amount of the pseudo bass (level ratio L3 / L2 in the figure). ) Was used. However, the attenuation amount and the amplitude compression amount may be fixed parameters, and a pseudo bass sound may be generated based on only the lowest frequency parameter. Alternatively, the pseudo bass may be generated based only on the attenuation amount and the lowest frequency without considering the amplitude compression change in the pseudo bass.

(6) In the above embodiment, when switching and using any one of a plurality of sound systems, the minimum frequency for each sound system is stored in advance, and according to the switching status of the sound system used. Thus, the pseudo bass effect may be automatically set.

(7) Control data (pseudo bass control data) for performing pseudo bass control may be included in a part of tone color data of each tone color. Further, the tone color data may include a plurality of pseudo bass control data corresponding to different lowest frequencies. In that case, if the user designates the minimum frequency of the sound system 12 in advance, then it is possible to automatically select and use the pseudo bass control data that matches the minimum frequency by simply selecting the tone. become.

(8) In the first and second embodiments using the waveform memory sound source, the analysis / creation processing of the waveform data stored in the waveform memory is performed. Is not required. Waveform data (normal musical sound waveform data 38 and pseudo-low sound waveform data 52) analyzed and created in advance is stored in the waveform memory, and the present invention can be implemented using the stored waveform data.

(9) In the third and fourth embodiments using the FM sound source, an algorithm in which two operators are connected in parallel is used to generate a pseudo bass sound, but other algorithms may be used.
For example, when using an algorithm in which two operators are connected in series, pitch data having the same pitch as the frequency of the low-frequency component that is not reproduced is set, and the operator on the modulator side uses the multiplier “1” to generate a waveform having the same pitch as that frequency. Data is generated, and the operator on the carrier side may generate waveform data having a pitch twice the frequency by a multiplier “2”. By applying frequency modulation to the waveform data with the same pitch as the waveform data with the double pitch, sideband frequency components are generated at intervals of frequencies corresponding to the same pitch with the double pitch as the center. To do. A pseudo bass sound can be generated by using the carrier component having the double pitch and the side band component (having a pitch that is three times the frequency of the low frequency component that is not reproduced).

In this case, the volume ratio between the carrier component and the one sideband component above is determined by the output level of the operator on the modulator side. In order to facilitate control, it is preferable that the envelope of the operator on the modulator side is not changed over time, that is, the volume ratio is set to a fixed value.
For the envelope of the carrier-side operator, an envelope parameter may be set so as to change over time while maintaining the relationship between the volume of the low frequency component not reproduced and the equal loudness.

(10) In the above embodiment, the pseudo bass is generated by the waveform memory sound source or the FM sound source, but the sound source types are not limited to these two. For example, in the case of a sound source of a harmonic synthesis system or a partial sound synthesis system, pseudo bass can be generated using one or more of a plurality of oscillators of each channel. In the case of a ring modulation type sound source, overtones generated by ring modulation of two series of oscillators can be used for pseudo bass. If the sound source is capable of nonlinear conversion of the waveform data, a pseudo bass can be generated based on the harmonics generated by the nonlinear conversion. In addition, you may apply to a physical model sound source and an analog modeling sound source.

(11) Although the pseudo bass effect can be turned on / off in the above embodiment, it may be always turned on.
(12) Although the minimum frequency is set by the user in the above embodiment, data indicating individual minimum frequencies of a plurality of sound systems may be stored. By simply selecting a sound system to be used, a corresponding minimum frequency is automatically determined, and a pseudo bass effect corresponding to the minimum frequency can be automatically set.

It is a hardware block diagram of the musical tone synthesis system of the first embodiment of the present invention. It is a flowchart of (a) note-on event processing routine and (b) normal sound generation control subroutine. It is a block diagram which shows the content of the waveform data creation process in 1st Example. It is a block diagram which shows the content of the waveform data analysis process in 1st Example. It is a figure which shows an equal loudness curve. It is a figure which shows the component analysis result of a waveform. It is an envelope conversion characteristic figure in the 1st example. It is a flowchart of the sound generation control routine with pseudo bass in the first embodiment. It is a figure which shows the example of the volume envelope in 1st Example. It is a block diagram which shows the principal part of the waveform data creation process in 2nd Example. It is a flowchart of the sound generation control routine with pseudo bass in the second embodiment. It is a flowchart of the control routine in 3rd, 4th Example. It is a block diagram of the algorithm in 3rd, 4th Example.

Explanation of symbols

    2 ... Hard disk, 4 ... Removable disk, 6 ... Display, 8 ... Input device, 10 ... Sound board, 12 ... Sound system, 14 ... Bus, 16 ... MIDI interface, 18 ... Timer 20 …… CPU, 22 …… ROM, 24 …… RAM, 30 …… material waveform data, 32 …… deterministic frequency component, 34 …… noise component waveform data, 36 …… waveform synthesis unit, 38 …… Normal musical sound waveform data, 40 …… Waveform analysis unit, 42 …… FFT analysis processing unit, 44 …… Continuous component separation unit, 46 …… Synthesis unit, 48 …… Subtraction unit, 50 …… Minimum frequency data, 52 …… Pseudo bass waveform data, 54 …… Attack & loop information, 60 …… Pseudo bass synthesizer, 62 …… Harmonic wave generator, 64 …… Amplitude controller, 66 …… Multiple waveform mixer, 67 …… Extractor, 68 ... Envelope converting unit, 72, 74 ...... amplitude control unit, 76 ...... mixing unit, 78 ...... pseudo low tone inclusive waveform data.

Claims (3)

In a waveform signal generation method for generating waveform signals of a plurality of sound generation channels in order to generate musical sounds via an electroacoustic transducer,
A process of receiving pronunciation instruction information with a specified pitch;
A determination step of determining whether the designated pitch is equal to or lower than a predetermined boundary pitch related to the electroacoustic transducer;
A first waveform signal generating step of generating a first waveform signal by an algorithm combining a plurality of operators, provided that it is determined in the determining step that the designated pitch is not less than or equal to the boundary pitch;
On the condition that the specified pitch is determined to be less than or equal to the boundary pitch in the determination process, the algorithm is a combination of the plurality of operators, and is a harmonic of the specified pitch and the greatest common divisor of the frequency. Is a second waveform signal generation process for generating a second waveform signal including a plurality of overtones that are equal to or higher than the boundary pitch at which the designated pitch becomes the pseudo-bass signal, and the waveform data of the pitch of the designated pitch And the second operator that performs frequency modulation on the waveform data having a pitch twice the designated pitch with the waveform data output by the first operator. And a second waveform signal generation process for generating the waveform signal. In a waveform signal generating device for generating waveform signals of a plurality of sound generation channels in order to generate musical sounds via an electroacoustic transducer,
Means for receiving pronunciation instruction information with a specified pitch;
Determining means for determining whether the designated pitch is equal to or lower than a predetermined boundary pitch related to the electroacoustic transducer;
First waveform signal generating means for generating a first waveform signal by an algorithm combining a plurality of operators, provided that it is determined in the determining means that the specified pitch is not less than or equal to the boundary pitch;
On the condition that the specified pitch is determined to be less than or equal to the boundary pitch in the determining means, the algorithm is a combination of the plurality of operators, and is a harmonic of the specified pitch and the greatest common divisor of the frequency. Is a second waveform signal generating means for generating a second waveform signal including a plurality of overtones that are equal to or higher than the boundary pitch at which the specified pitch is obtained as a pseudo bass signal, and waveform data at a pitch of the specified pitch And the second operator that performs frequency modulation on the waveform data having a pitch twice the designated pitch with the waveform data output by the first operator. And a second waveform signal generation means for generating the waveform signal. A computer-readable recording medium storing a program for causing a processing device to execute the method according to claim 1.

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