JPS60840B2 - stereo system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a stereo system having a reverberation adding device.

The creation of stereo sources such as records from secondary sources can be roughly divided into two methods: using the signal picked up by a microphone as a stereo source as it is, and using the original signal distributed appropriately to each stereo channel. In order to create a sense of realism, a reverberant signal is usually created and added to each channel using a reverberation adding device, or a reverberation signal is created and added to each channel after mixing a portion of the signals of each channel. .

However, no signal creation has been done that takes into particular consideration the correlation coefficient regarding the reverberant signal added to each channel. Incidentally, the most desirable sense of presence, that is, the sense of spaciousness of the sound field, can be expressed by the interaural correlation coefficient of reverberant sound, and the correlation coefficient that provides this sense of spaciousness has frequency characteristics as shown in FIG.

Therefore, it is desirable to add reverberant sound having the interaural correlation coefficient shown in FIG. 1 to the original sound according to each frequency.

This invention focuses on the above-mentioned points, and attempts to provide a stereo system that gives the optimal sense of spaciousness to the sound field by giving frequency characteristics to the correlation coefficients of reverberation signals between each channel. It is something to do.

Examples will be described below with reference to the drawings.

FIG. 2 shows a reverberant signal forming circuit on the source production side, where A is a reverberant signal adding device and B is a filter device for imparting frequency characteristics to the reverberant signal. This reverberant signal addition device A includes two speakers 1 and 2, and r, ~
Echo camber using four microphones 3 to 6 with an interval set to r3 is used. In addition, the filter device B includes a bandpass filter 7~ with a center frequency of ``ol~puo3.
9 are connected as shown in the figure, the reverberant signals of each channel are frequency-divided, and the reverberant signals of microphones 4 to 6 are sent to the mixer 1.
Mix at 0. By doing this, the relationship between the correlation coefficient p〆o of the reverberant signal appearing between each channel and the microphone interval r is approximately p〆p〆o.

=SinZ; Gorno2 Rikiko. It can be expressed as r (
However, c is the speed of sound).

As a result, in order to set each correlation coefficient pnao, ~pnao3, it is only necessary to change the microphone spacing r, ~r3,
In order to give it a frequency characteristic, the center frequencies 〆ol to 〆o3 of the bandpass filters 7 to 9 can be appropriately set. FIG. 3 shows the characteristics of the correlation coefficient with respect to the microphone spacing r. As described above, if a sound field is formed by reproducing the reverberation signals appearing at the terminals ■ and ■ together with the original sound, the interaural correlation coefficient can have the characteristics shown in FIG. 1. Incidentally, the reverberation signal adding device A can also be based on the electric circuit shown in FIG.

In the figure, 11 is a mixer, 12 and 13 are reverberation generators with different constants (preferably constants that make the correlation coefficient zero), 14 and 14' are anti-phase circuits, and 20, 21, 20', 21
' is a mixer. In this case, by adjusting the attenuators 15, 16, 15', and 16', the two in-phase components from the reverberation generator 12 and the two anti-phase components from the reverberation generator 13 are combined into the mixer. 20, 21, 20
By changing the mixing ratio when mixing by ', 21', the correlation coefficient can be adjusted. In addition, this reverberation adding device A uses two echo camber microphones, the distance between them is sufficiently separated (it is sufficient to separate the two microphones), and the correlation coefficient of the signal between them is set to zero. The signal from the reverberation generating device 12, 1 in FIG.
It is also possible to add them separately to the output sides of 3.

Furthermore, the reverberation generating devices 12 and 13 of the same aircraft may be formed by two metallic reverberation boards. An embodiment of a stereo system using the reverberation adding device A and filter device B will be described below.

FIG. 5 shows the remaining signal from the filter device B to mixer 17,
After mixing in step 18, the signals are reproduced in two channels via a two-channel recording medium 19 such as a record or tape. Further, FIG. 6 shows a system in which the main signal and the reverberant signal are reproduced separately in four channels via a four-channel recording medium 19'.

Further, FIG. 7 shows a system in which two channels of mixed main signals and reverberant signals and another two channels of echo signals are reproduced in four channels separately via a four-channel recording medium 19'.

In this case, the correlation coefficients of the reverberation signals from each filter device B, B2 are assumed to be zero. Furthermore, FIG. 8 shows a system in which two reverberant signals with a correlation coefficient of zero are created by a reverberation adding device A', and these are reproduced together with the main signal via a four-channel recording medium 19'.

In this case, the correlation coefficient of the reverberation signal and the frequency characteristics of the correlation coefficient are adjusted on the reproduction side (not shown) according to the listener's preference. As described above, the present invention adds a part of the main signals of at least two channels to a reverberation adding device, creates a plurality of reverberation signals having appropriate correlation coefficients there, and adds the reverberation signals to a filter device for frequency division. However, the Isoko signal having the frequency characteristics obtained here is recorded or reproduced together with the main signal.

Therefore, a plurality of reverberation signals having appropriate correlation coefficients are obtained by the reverberation adding device, and since the reverberation signals are given appropriate frequency characteristics by the filter device, the frequency characteristics are not given to the correlation coefficients of the reverberation signals. Therefore, it becomes possible to obtain reverberant sound that satisfies the characteristics shown in FIG. 1, and it becomes possible to form a sound field that provides an optimal sense of spaciousness.

[Brief explanation of the drawing]

Figure 1 is a frequency characteristic diagram of the inter-ear correlation coefficient that provides an optimal sense of spaciousness, Figure 2 is a block diagram of the reverberant signal forming circuit, Figure 3 is a characteristic diagram of the correlation coefficient with respect to microphone spacing, and Figure 4 is a block diagram of another embodiment of the reverberation adding device, and FIGS. 5 to 8 are block diagrams of each embodiment of the stereo system. A: Reverberation adding device, B: Filtering device. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A reverberation adding device into which a portion of the main signals of at least two channels is input and which generates a plurality of reverberation signals having appropriate correlation coefficients as output, and a filter device into which the reverberation signals are input, the filter device comprises a plurality of parallel-connected bandpass filters, each having a settable center frequency different from each other, and a separate bandpass filter having a center frequency corresponding to each of the bandpass filters,
One of the reverberation signals is added to the bandpass filters connected in parallel, and the remaining reverberation signals are separately added to each of the separate bandpass filters to obtain a reverberation signal having frequency characteristics, and the reverberation signal is used as the main A stereo system characterized by recording or reproducing signals together.