JP6954014B2 - Acoustic output device - Google Patents

Description

The present invention relates to, for example, an acoustic output device.

There is a demand for hearing-through functions in acoustic output devices such as earphones and headphones. Hear-through refers to a function that allows a user to hear ambient sounds as if they were not wearing an acoustic output device (see, for example, Patent Document 1).

Special Table 2015-537465

By the way, when a user wears an acoustic output device and listens to a target sound supplied from an external terminal such as a music player (hereinafter referred to as "target sound") together with ambient sounds, the audibility of the target sound deteriorates. I have something to do.
The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the audibility of the target sound when the sound output device is worn and the target sound is listened to together with the ambient sound. The purpose is to provide technology to suppress it.

In order to achieve the above object, the sound output device according to one aspect of the present invention is predetermined with respect to the first microphone that collects the ambient sound of the user and the first signal based on the sound collection of the first microphone. An equalizer that imparts frequency characteristics, a speaker that emits sound toward the user's drum membrane, a second microphone that collects sound in the vicinity of the speaker, and a reverse-phase signal of the second signal based on the sound collected by the second microphone. A reverse-phase signal generation circuit that generates Includes an adder that adds an output signal from the equalizer and outputs it to the speaker.

It is a block diagram which shows the structure of the earphone which concerns on 1st Embodiment. It is a figure which shows the example of the change of a coefficient by a processing circuit. It is a figure which shows the example of the change of a coefficient by a processing circuit. It is a figure which shows the structure of an earphone. It is a figure which shows the wearing state of an earphone. It is a block diagram which shows the structure of the earphone which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the earphone which concerns on 3rd Embodiment. It is a figure which shows the headphone which concerns on 4th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of an earphone 10a which is an example of an acoustic output device according to the first embodiment. As shown in this figure, the earphone 10a includes microphones 110, 150, amplifiers 112, 134, 152, ADC 114, 154, equalizer 116, IF 122, adder 130, DAC 132, speaker 140, reverse phase signal generation circuit 156 and multiplication. Includes vessel 159. When the earphone 10a is worn by the user, the sound emitting direction of the speaker 140 is arranged in the direction toward the user's ear canal, and the microphone 150 is the sound emitting direction of the speaker 140 and is acoustically coupled to the ear canal. It is placed in the space.

The microphone 110 (first microphone) picks up the ambient sound of the user who wears the earphone 10a. The amplifier 112 amplifies the signal (first signal) picked up by the microphone 110, and the ADC (Analog to Digital Converter) 114 converts the signal amplified by the amplifier 112 into a digital signal.
The equalizer 116 performs a correction process on the output signal of the ADC 114, for example, a process of compensating in advance for the characteristic lost due to sound insulation when the earphone 10a is worn, and the processed signal is sent to the first input terminal of the adder 130. Supply.

The IF (InterFace) 122 is an interface that wirelessly receives a signal from the external terminal 200. The signal received by the IF 122 is a signal reproduced by the external terminal 200, that is, a target sound signal of a sound (target sound) to be heard by the user. The target sound signal received by the IF 122 is supplied to the second input terminal of the adder 130.
The target sound signal is, for example, a music signal reproduced by the external terminal 200. Further, the IF 122 may be configured to receive the target sound signal by wire instead of wirelessly.

The processing circuit 124 recognizes whether the external terminal 200 is in the playback state or the stopped state by the state signal notified from the external terminal 200, generates a coefficient α according to the state, and generates a coefficient α according to the state, and the multiplier 159. Supply to.
Specifically, when the processing circuit 124 recognizes that the external terminal 200 has changed from the stopped state to the reproduced state by the state signal, the coefficient α is changed from “0” to the time Tu as shown in FIG. 2, for example. Apply and change smoothly to "1". Therefore, the coefficient α becomes “1” after the time Tu has elapsed after the external terminal 200 has changed from the stopped state to the playback state.

On the other hand, when the processing circuit 124 recognizes that the external terminal 200 has changed from the playback state to the stopped state by the state signal, the coefficient α is changed from “1” to the time Td as shown in FIG. 3, for example. Change smoothly to "0". Therefore, the coefficient α becomes “0” after the time Td has elapsed after the external terminal 200 has changed from the playback state to the stopped state.

If the external terminal 200 is, for example, a PC (Personal Computer) or the like and has a configuration in which music or the like is reproduced by executing an application program to output a target sound signal, the processing circuit 124 and the external terminal 200 are integrated. It becomes the PC that has been converted.
Further, regarding the time Tu and Td, if they are too short, they are recognized as abnormal noise by the user, so that each is preferably 1 millisecond or more.

The adder 130 adds the signals supplied to each of the first input end, the second input end, and the third input end, and supplies the signals to the DAC (Digital to Analog Converter) 132. The DAC 132 converts the signal added by the adder 130 to analog, and the amplifier 134 amplifies the signal converted by the DAC 132. The speaker 140 converts the signal amplified by the amplifier 134 into air vibration, that is, sound, and outputs the signal.

The microphone 150 (second microphone) is provided in the vicinity of the speaker 140, and collects the sound output from the speaker 140 and the like. The amplifier 152 amplifies the signal (second signal) picked up by the microphone 150, and the ADC 154 converts the signal amplified by the amplifier 152 into a digital signal and supplies it to the reverse phase signal generation circuit 156.

The reverse phase signal generation circuit 156 generates a reverse phase signal having substantially the same volume (amplitude) by adjusting the frequency, amplitude, and phase in a relationship in which the phase of the output signal from the ADC 154 is inverted. The reverse phase signal generation circuit 156 limits the generated reverse phase signal to, for example, a component having a frequency of 200 Hz or less by a built-in low-pass filter.

The multiplier 159 multiplies the reverse phase signal by the reverse phase signal generation circuit 156 by a coefficient α, and supplies the multiplication signal resulting from the multiplication to the third input terminal of the adder 130.
In FIG. 1, for example, if the equalizer 116, the adder 130, the reverse phase signal generation circuit 156 and the multiplier 159 are configured by, for example, a DSP (Digital Signal Processor) integrated with one or more chips, space saving can be achieved. Can be planned.

FIG. 4 is a diagram showing the structure of the earphone 10a.
As shown in this figure, the earphone 10a is, for example, a canal type and includes a housing 160 and an earpiece 180.
The housing 160 has a substantially cylindrical shape. Speakers 140, microphones 110 and 150 are provided in the internal space of the housing 160. Specifically, the speaker 140 is attached so as to partition the internal space of the housing 160, and the sound emitting surface of the speaker 140 is directed toward the ear canal.
The microphone 150 is attached to the space near the ear canal (on the right side in the figure) in the space where the speaker 140 is emitted, for example, in the space partitioned by the speaker 140 in the internal space of the housing 160.
The housing 160 is provided with one or a plurality of ventilation holes 168 for ventilating the space near the ear canal to the outside among the internal spaces partitioned by the speaker 140 when worn.
On the other hand, the microphone 110 is provided on the opposite side of the internal space partitioned by the speaker 140 in the space opposite to the ear canal.

The earpiece 180 is formed into a hollow bullet shape that opens at the opening 186 with an elastic material such as polyvinyl or sponge, and is detachable from the ear canal side of the housing 160. When the earpiece 180 is attached to the housing 160, the opening 186 communicates with the internal space of the housing 160.

Of the elements constituting the earphone 10a shown in FIG. 1, elements other than the microphones 110, 150 and the speaker 140 are provided in the internal space of the housing 160, for example, in the vicinity of the microphone 110, but are omitted in FIG. ing.

FIG. 5 is a diagram showing a wearing state of the earphone 10a, and more specifically, is a diagram showing a state in which the earphone 10a is worn on the right ear of the user W. As shown in this figure, the earpiece 180 of the earphone 10a is inserted into the ear canal 314. Specifically, the earpiece 180 is inserted into the ear canal 314 in the direction of the opening 186 toward the eardrum 312, while a part of the housing 160 is exposed from the ear canal 314.

Next, the operation of the earphone 10a will be described. First, a case where the external terminal 200 is in the playback state will be described.
After the external terminal 200 changes from the stopped state to the playback state and the time Tu elapses, the coefficient α is “1”. As shown in FIG. 5, when the earphone 10a is worn by the user W, the speaker 140 uses an adder signal 130, specifically, a peripheral sound signal picked up by the microphone 110, and an external terminal 200. It is sounded based on the addition signal of the target sound signal supplied from the above and the reverse phase signal multiplied by "1" as the coefficient α.

The reverse phase signal generation circuit 156 outputs a reverse phase signal having a frequency of 200 Hz or less among the signals picked up by the microphone 150. Therefore, when the speaker 140 pronounces based on the added signal, it reaches the eardrum 312 in a state where a component having a frequency of 200 Hz or less is suppressed among the signals of the ambient sound. Examples of the ambient sound suppressed by the reverse phase signal include a blowing sound, a mechanical sound of an engine, and a running sound.

As described above, if the external terminal 200 is in the reproduction state of the target sound signal, the user wearing the earphone 10a perceives the noise of the low frequency component of the ambient sound in the canceled state. Therefore, according to the earphone 10a, the low frequency portion of the sound based on the target sound signal, particularly the rhythm sound, is not masked by the ambient sound, so that the audibility of the sound based on the target sound signal can be improved. ..

When the earphone 10a is not worn, the user W vibrates the eardrum 312 through the ear canal 314 (air) and transmits the air conduction sound to the auditory nerve, and the vibration is transmitted directly to the auditory nerve through the skin and bones. It is perceived by adding up the transmitted bone conduction sound. The bone conduction sound includes a self-voice sound that is perceived by transmitting the vibration of one's vocal cords to the auditory nerve via a bone or the like.
On the other hand, when the earphone 10a is worn by the user W, the ear canal 314 of the user W is blocked or sound-insulated by the earpiece 180, so that the sound emitted from the speaker 140 and the sound emitted from the speaker 140 leak into the ear canal 314 through the ventilation hole 168. Sound is perceived by adding the sound and the bone conduction sound.
The sound emitted from the speaker 140 when the earphone 10a is worn is transmitted to the eardrum 312 in a state where a certain band component is lost due to the obstruction / sound insulation of the ear canal 314, which is different from the transmission characteristics when the earphone 10a is not worn. To reach. However, since the peripheral sound signal picked up by the microphone 110 is compensated in advance by the equalizer 116 for the loss due to the blockage / sound insulation by the earpiece 180 at the time of wearing, the user W can use the sound emitted from the speaker 140. Of these, the ambient sound can be perceived as if the earphone 10a is not worn, with a natural feeling.

The operation of the earphone 10a when the external terminal 200 is in the stopped state will be described.
After the external terminal 200 changes from the playback state to the stopped state and the time Td elapses, the coefficient α becomes “0”. Also, the target sound signal is not supplied from the external terminal 200. Therefore, when the earphone 10a is worn by the user W as shown in FIG. 5, if the external terminal 200 is in the stopped state, only the sound based on the ambient sound signal picked up by the microphone 110 is the speaker. Emitted from 140.
Since the peripheral sound signal picked up by the microphone 110 is pre-compensated for the loss due to the blockage / sound insulation by the earpiece 180 by the compensation process by the equalizer 116, the user W emits the sound from the speaker 140 as in the playback state. The ambient sound to be heard can be perceived as if the earphone 10a is not worn, with a natural feeling.

The operation of the earphone 10a immediately after the external terminal 200 changes from the stopped state to the playback state will be described.
When the state is changed from the stopped state to the reproduced state, the processing circuit 124 smoothly changes the coefficient α from “0” to “1” as shown in FIG.
Therefore, the amplitude of the multiplication signal supplied to the third input end of the adder 130 does not increase sharply. Therefore, according to the earphone 10a, when the external terminal 200 is in the playback state, it is possible to prevent the user from recognizing the abnormal noise caused by the start of the noise canceling operation.

Immediately after the external terminal 200 changes from the playback state to the stopped state, the processing circuit 124 smoothly changes the coefficient α from “1” to “0” as shown in FIG. Therefore, the amplitude of the multiplication signal supplied to the third input end of the adder 130 does not suddenly become zero. Therefore, according to the earphone 10a, when the external terminal 200 is stopped, it is possible to prevent the user from recognizing an abnormal noise caused by the stop of the noise canceling operation.

<Second Embodiment>
Next, the second embodiment will be described. FIG. 6 is a block diagram showing a configuration of the earphone 10b according to the second embodiment.
As shown in this figure, the earphone 10b has a built-in processing circuit 124 for detecting the state of the external terminal 200.
In the second embodiment, the processing circuit 124 determines that the external terminal 200 is in the stopped state when the volume (or volume time average value) of the target sound signal received by the IF 122 is less than the threshold value. When the volume (or volume time average value) of the target sound signal is equal to or greater than the threshold value, it is determined that the external terminal 200 is in the playback state. The processing circuit 124 smoothly changes the coefficient α from “0” to “1” over time Tu when changing from the stopped state to the reproduced state, and when changing from the reproduced state to the stopped state, the coefficient The point that α is smoothly changed from “1” to “0” over time Td is the same as that of the first embodiment.

In FIG. 6, the processing circuit 124 may be composed of, for example, an equalizer 116, an adder 130, an antiphase signal generation circuit 156, and a multiplier 159, as well as a DSP (Digital Signal Processor) of one or more chips. ..

According to the earphone 10b according to the second embodiment, if it is determined that the external terminal 200 is in the playback state at the time of wearing, the user can improve the audibility of the sound based on the target sound signal, and the external terminal can be improved. If it is determined that the 200 is in the stopped state, the peripheral sound can be perceived by the user as if it were not worn.
Further, according to the earphone 10b, the external terminal recognizes the abnormal noise when the external terminal 200 changes from the stopped state to the playback state and when the external terminal 200 changes from the playback state to the stopped state. It can be prevented without receiving the notification of the status signal from 200.

In the second embodiment, in the processing circuit 124, the threshold value of the volume used when the external terminal 200 determines that it is in the stopped state is set to be smaller than the threshold value of the volume used when the external terminal 200 determines that it is in the playback state. Then, a hysteresis characteristic may be provided for determining the stopped state or the reproduced state.

<Third Embodiment>
Subsequently, the third embodiment will be described. FIG. 7 is a block diagram showing a configuration of the earphone 10c according to the third embodiment.
As shown in this figure, the earphone 10c has a built-in processing circuit 124 for detecting the state of the external terminal 200 and also has an IF 123, as in the second embodiment.

In the third embodiment, the external terminal 200 transmits a state signal indicating whether it is in the playback state or the stopped state, for example, wirelessly, and the IF 123 receives the state signal.
The processing circuit 124 recognizes whether the external terminal 200 is in the playback state or the stopped state based on the state signal received by the IF 123, generates a coefficient α according to the state, and supplies the coefficient α to the multiplier 159. ..
In the third embodiment, the external terminal 200 may be configured to receive the status signal by wire instead of wirelessly.

According to the earphone 10c according to the third embodiment, when the external terminal 200 is in the playback state, the user can improve the audibility of the sound based on the target sound signal, and when the external terminal 200 is in the stopped state, the ambient sound is described. It can be perceived by the user as if it were not worn. Further, according to the earphone 10c, it is possible to prevent the user from recognizing an abnormal noise when the state of the external terminal 200 changes.

In the first, second and third embodiments, the case where the earphones 10a, 10b or 10c are worn on the right ear has been described as an example, but the earphones may be worn on the left ear. In addition, two earphones 10a (10b, 10c) having the same configuration are prepared so that one is worn on the right ear and the other is worn on the left ear, and the earphone 10a (10b or 10c) worn on the left ear is stereo. The left signal of the above may be supplied to the earphone 10a (10b or 10c) worn on the right ear, and the stereo right signal may be supplied from the external terminal 200, respectively.

Further, in the first, second and third embodiments, if the coefficient α is “0”, the reverse phase signal generation circuit 156 may be configured to stop the generation of the reverse phase signal to reduce power consumption. good.

<Fourth Embodiment>
In the above-described embodiment, the earphones 10a, 10b and 10c are exemplified as the acoustic output device, but they can also be applied as headphones.

FIG. 8 is a diagram showing a configuration of headphones 1 which is an example of the acoustic output device according to the fourth embodiment.
As shown in this figure, the headphone 1 includes a headphone unit 10L, 10R, a headband 3, and arms 4L and 4R. The headband 3 is made of elastic metal, resin, or the like, and has a shape that draws an arc in the longitudinal direction. Of both ends of the headband 3, the headphone unit 10L for the left ear is attached to one end side (left side in the figure) via the arm 4L, and the other end side (right side in the figure) via the arm 4R. The headphone unit 10R for the right ear is attached.

The headphone unit 10L has a substantially cylindrical housing 160 and ear pads 182 attached to the housing 160. The electrical configuration of the headphone unit 10L is the same as that of any of the above-mentioned earphones 10a, 10b or 10c, and includes microphones 110 and 150 and a speaker 140, respectively.
The headphone unit 10R has almost the same configuration as the headphone unit 10L.
A stereo left signal is supplied to the headphone unit 10L, and a stereo right signal is supplied to the headphone unit 10R from the external terminal 200.

When wearing the headphone 1, the user holds the headphone units 10L and 10R to widen the arc of the headband 3, and puts the ear pad 182 of the headphone unit 10L in the left ear and the ear pad 182 of the headphone unit 10R in the right ear. Cover each. Due to its elasticity, the headband 3 generates a restoring force that tries to bring the ends of the headband 3 closer to each other. Therefore, the headphone units 10L and 10R located at the end of the headband 3 apply lateral pressure to the user's head when worn. Due to this lateral pressure, the headphone 1 is held in a predetermined position.

When the headphones 1 are worn by the user, the ears are shielded by the ear pads 182. The sound transmission is almost the same as that of the earphones 10a, 10b or 10c.
Therefore, according to the headphone 1, when the external terminal 200 is in the playback state, the user can improve the audibility of the sound based on the stereo target sound signal, and when the external terminal 200 is in the stopped state, the peripheral sound can be heard. It can be perceived by the user as if it were not worn. Further, according to the headphone 1, it is possible to prevent the user from recognizing an abnormal noise when the state of the external terminal 200 changes.

<Application example / Modification example>
In the first embodiment and the like, the coefficient α has a configuration in which the coefficient α changes smoothly as shown in FIG. 2 or FIG. 3, but a configuration in which the coefficient α changes stepwise to the extent that an abnormal noise is not felt may be used.

<Additional notes>
From the above-mentioned first embodiment and the like, for example, the following aspects can be grasped.

<Aspect 1>
The sound output device according to preferred embodiment 1 of the present invention is an equalizer that imparts predetermined frequency characteristics to a first microphone that collects the ambient sound of the user and a first signal based on the sound collection of the first microphone. A reverse phase signal that generates a reverse phase signal of a speaker that emits sound toward the user's drum membrane, a second microphone that collects sound in the vicinity of the speaker, and a second signal based on the sound picked up by the second microphone. The generation circuit, a multiplier that multiplies the antiphase signal by a coefficient based on the supply state of the target sound signal indicating the target sound, the target sound signal, the multiplication signal by the multiplier, and the output signal by the equalizer. Includes an adder that adds and outputs to the speaker.
According to the acoustic output device according to the first aspect, it is possible to suppress the deterioration of the audibility of the target sound when the target sound is listened to together with the ambient sound by wearing the.

<Aspect 2>
In the acoustic output device according to the second aspect, in the acoustic output device according to the first aspect, when the output of the target sound signal is stopped, the coefficient becomes small, and when the target sound signal is output, the coefficient becomes large. Become.
According to the acoustic output device according to the second aspect, it is possible to prevent the user from recognizing an abnormal sound when switching the output or stop of the target sound signal.

<Aspect 3>
In the acoustic output device according to the first aspect, when the volume level of the target sound signal becomes less than the threshold value, the acoustic output device according to the third aspect reduces the coefficient and raises the volume level of the target sound signal. It has a processing circuit that increases the coefficient when it exceeds the threshold value.
According to the acoustic output device according to the third aspect, since the coefficient is changed according to the volume level of the target sound signal, the output or stop of the target sound signal can be performed without the need for the configuration of receiving the notification from the external terminal 200. It is possible to prevent the user from recognizing an abnormal noise when switching.

1 ... Headphones, 10a, 10b ... Earphones, 110 ... Microphone (first microphone), 116 ... Equalizer, 124 ... Processing circuit, 130 ... Adder, 140 ... Speaker, 150 ... Microphone (second microphone), 156 ... Reverse phase Signal generation circuit, 159 ... Multiplier, 200 ... External terminal.

Claims (3)

The first microphone that collects the user's ambient sound and
An equalizer that imparts a predetermined frequency characteristic to the first signal based on the sound collection of the first microphone, and
A speaker that emits sound toward the user's eardrum,
The second microphone that collects the sound near the speaker and
An anti-phase signal generation circuit that generates an anti-phase signal of the second signal based on the sound picked up by the second microphone, and
A multiplier that multiplies the reverse phase signal by a coefficient based on the supply state of the target sound signal indicating the target sound.
An adder that adds the target sound signal, the multiplication signal by the multiplier, and the output signal by the equalizer and outputs them to the speaker.
Acoustic output device including. When the output of the target sound signal is stopped, the coefficient becomes small and
When the target sound signal is output, the coefficient becomes large.
The acoustic output device according to claim 1. When the volume level of the target sound signal becomes less than the threshold value, the coefficient is reduced.
It has a processing circuit that increases the coefficient when the volume level of the target sound signal exceeds the threshold value.
The acoustic output device according to claim 1.

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