JPH0259000A - Sound image static reproducing system - Google Patents

Abstract

PURPOSE:To improve both the attendant feeling and the directional feeling of sounds by controlling a sound image static for a frequency band from which the perception of an auditory direction can be obtained using plural speakers, reproducing the sounds from the plural speakers, executing no control for the sound image static for the other frequency bands, and reproducing the sounds using a single speaker. CONSTITUTION:Voices related to the second frequency band 22 and the third frequency band 23 to perceive the auditory directional feeling are reproduced using the plural speakers while sound image static control is executed. On the other hand, voices and environmental sounds related to the first frequency band 21 and the fourth frequency band 24 not to perceive the directional feeling are reproduced from the single speaker provided near a television set, etc. Consequently, since the plural speakers are never used when the voices of the first and fourth frequency bands 21 and 24 are to be reproduced, used, the blur of the sounds caused by plural sound sources never occurs, and the accuracy of the sound image static of the second and third frequency bands 22 and 23 to obtain the perception of the direction can be improved. Thus, both the attendant feeling and the directional feeling of the sounds can be improved in a communication conference.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention focuses on the frequency band in which auditory upward direction perception occurs in a sound one-image localization reproduction system in a communication conference using video. Regarding the sound image localization playback method, the sound image localization control is performed for the audio C in the other frequency bands, and the sound image localization control is not performed for the two audio C in the other frequency bands, and the playback position is placed close to the video part of the monitor etc. It is something.

"Prior Art" FIG. 5 shows an example of a conventional sound image localization reproduction system for video conferences. In the same figure, A shows the monitor 12 for the listener 11.
The front center of the monitor 12 (monaural sound is played by installing the Nispy Power 13C. Figure B shows the front center of the monitor 12 on both sides (
; Install speakers 13L and 13R to reproduce stereo sound (2 channels).

Figure C shows the front, center, and both sides of the monitor 12 (Nispee power units 13C, 13L, and 13R are installed to reproduce 3-channel stereo sound. This figure shows the case where 4-channel stereo sound is reproduced. The difference is that the Nispee force 13B is installed behind the listener 11.The system configuration of B-D is effective from the viewpoint of improving the sense of presence of sound in a teleconference.

For example, regarding Figure B (2), the listener 11 heard the voice of the person in the center clearly compared to the voices of the people on both sides of the monitor 12 (= three people 14 displayed side by side). There is a problem that it is difficult to perceive with a sense of direction (low sense of sound localization).As a way to deal with this point,
As shown in C and D of the same figure (speakers 13L on both sides,
A center speaker 13C is installed between 13R and 13C to improve the sense of direction as well as the sense of presence of the sound during the communication conference.

In a conventional system using three types of speakers (left side, center, and right side) (Figures C and D), each speaker performs sound image localization for audio in all frequency bands. Targeting this entire frequency band has become a problem. In other words, due to human auditory ability, the frequency band in which direction perception can be obtained is limited, and performing sound localization control using multiple speakers for sounds in that frequency band is an effective way to improve the reproduction of direction sense. On the other hand, in the frequency band where direction perception cannot be obtained, when multiple speakers are used, there are multiple point sound sources, resulting in "blur" in the reproduced sound, which makes it difficult to obtain direction perception. The first problem is that the accuracy of sound image localization is reduced.

By the way, in a video conference, it is known that there is an interaction in which the voice of the person being projected, that is, the sound image, is attracted to the mouth of the person being projected. Sound in a frequency band where direction perception cannot be obtained is originally difficult to intuitively localize, but by increasing the interaction with the image above, it is possible to artificially localize the sound image to the mouth of the person in the image. In order to enhance the interaction with the elephant, it is more effective to place one sound source close to the mouth of the person shown on the TV.However, in the conventional system, Then, as mentioned above, since the sound in the frequency band in which direction perception cannot be obtained is reproduced from a plurality of sound sources, there is a second problem that the above-mentioned interaction cannot be effectively utilized.

The purpose of this invention is to use phase differences and sound pressure level differences to localize sounds in frequency bands where direction perception can be obtained, and to localize sound images in frequency bands where direction perception cannot be obtained, and to localize sound images in frequency bands where direction perception cannot be obtained. Using pseudo (
The aim is to make it easier to localize the sound image in the 2-video section,
In order to eliminate the above-mentioned drawbacks of the conventional method, the frequency band is divided into a frequency band where upward auditory perception occurs and other frequency bands, and sound image localization is controlled using multiple speakers for audio in the former band, and sound image localization in the latter band is controlled using multiple speakers. The object of the present invention is to provide a sound image localization reproduction method in which sound is reproduced using a single speaker located close to an image area such as a monitor without controlling sound image localization.

"Means for Solving the Problem" According to the present invention, a frequency band is divided for each audio signal of a plurality of input channels to be generated for sound image localization, and the audio of the divided first frequency band is divided. The sound pressure level is adjusted when the signal is output to the playback channel, and the sound image localization is generated for the audio signal of the divided second frequency band (- phase difference (time difference) and sound The phase and level are adjusted so that a pressure level difference is generated, and a sound pressure level difference is generated between reproduction channels in order to generate sound image localization for the audio signal of the divided third frequency band. The level is adjusted, the correspondence data between the input channel and the playback channel, and the localization data that defines the sense of distance and sense of direction for sound image localization are set, and the second and third frequency bands are used to obtain an auditory sense of direction. For the first frequency band in which direction perception cannot be obtained, the sound image localization is controlled using a plurality of speakers, and the sound image localization is not performed and the sound is reproduced using a single speaker.

Frequency division is performed as follows. That is, FIG. 1 is an example showing the features of this invention regarding frequency band division (2).The human audible range 15 is 20 Hz to 20.000 Hz.
frequency band. In communication conferences such as video conferences and audio conferences, the range of human speech ranges from 100 Hz to 8.
Particular emphasis is placed on how to localize the sound image of audio in the OOOHz frequency band (: how to reproduce it with high precision and high fidelity.However, listener 1, whose hands are used to receive the sound,
It is known that the direction perception ability of No. 1 is within the human vocal range of 16 (smaller frequency band than No. 2). Sakai, Nakayama: Hearing and Psychoacoustics (Japan Acoustics Complete Edition, 1978, Coronasha, pp185) According to the literature (195), there are two types of perceptual methods regarding the human auditory ability to perceive direction.The first method is to perceive a sense of direction based on the phase difference (time difference) between two sounds. This perception range 17 is 20
It is said to be between 0 Hz and 1.300 Hz. The second method is to perceive a sense of direction based on the sound pressure level difference between two sounds, and this perception range 18 is from 200 Hz to
5. It is said to be OOOOHz.

As shown in the figure, when frequency bands are divided and organized from the perspective of sound image localization control, the human audible range 15 is a low-frequency first frequency band 2 related to voices that do not perceive a sense of direction and environmental sounds.
1, a second frequency band 22 in which a sense of direction is perceived by mixing a phase difference (time difference) and a sound pressure level difference, and a third frequency band 23 in which a sense of direction is perceived only by a sound pressure level difference. It is broadly divided into a high-frequency fourth frequency band 24 related to sounds that do not give a sense of direction and environmental sounds.

This invention provides a second frequency band 2 for perceiving an auditory sense of direction.
2 and the third frequency band 23 are reproduced while performing sound image localization control using a plurality of speakers, and on the other hand, the sound and environment related to the first frequency band 21 and the fourth frequency band 24C are reproduced without perceiving a sense of direction. Sound is reproduced from a single speaker close to a television or the like, and the sound image is simulated to be easily localized in the video section through interaction with the video.

"Example" FIG. 2 is an example of a playback system showing the features of this invention.

Speaker cabinets 25 are arranged around the monitor 12 on the right side, left side, upper side, and lower side, respectively, showing an example of a sound image localization reproduction system using two-channel stereo sound. The sound of the first frequency band 21 is reproduced from the lower speaker 26, and the sound of the fourth frequency band 24 is reproduced from the upper speaker 27 using a single speaker. The sound image of the second frequency band 22 is localized by adjusting the phase difference and the sound pressure level difference using the left and right speakers 28L and 28R. Further, the sound in the third frequency band 23 is localized using the left and right speakers 29L and 29R to adjust the sound pressure level difference.

FIG. 3 is a block diagram showing the configuration of an embodiment of the present invention, in which 26 is a first frequency band speaker, 2 sL,
28R is the second frequency band speaker (28L: first
For playback channel, 28R = 2nd playback channel FF+'
, N 29L + 29R is the third frequency band speaker (2g7.: for the first reproduction channel, 29R: for the second reproduction channel), 27 is the fourth frequency band speaker,
70 is an input terminal, 100 is a low frequency sound pressure level adjustment section, 20
0 is a phase difference/sound pressure level difference mixed sound image localization adjustment unit, 300
400 is a high frequency sound pressure level adjustment section; 500 is a frequency band division section; 600 is a reproduction channel sound image localization initial setting section; 700 is a control section.

In C:, which operates this, the frequency band dividing unit 500 selects the audio image localization initial setting unit 600 for the reproduction channel for the audio signals of m input channels transferred from the input terminal 70 according to a command from the control unit 700. The first specified
The audio signal of each channel is divided into bands based on the band setting data of the frequency bands 21 to 24 from 1 to 4, and the audio signal of the first frequency band 21 is sent to the low frequency sound pressure level adjustment section 100, The audio signal in the frequency band 22 is sent to the phase difference/sound pressure level difference mixed sound image localization adjustment section 200, the audio signal in the third frequency band 23 is sent to the sound pressure level difference sound image localization adjustment section 300, and the audio signal in the fourth frequency band 24 is sent to the sound image localization adjustment section 300. The high frequency sound pressure level adjustment section 400 adjusts the audio signal of
Transfer to.

The low-frequency sound pressure level adjustment unit 100 receives the specification from the reproduction channel sound disturbance localization initial setting unit 600 &: Therefore, the added audio signal obtained by adding the audio signals of m channels or m
The sound pressure level of the selected audio signal selected and extracted from the channels is adjusted, and the sound pressure level is adjusted and the audio signal is reproduced from the first frequency band speaker 26.

When the phase difference/sound pressure level difference mixed sound image localization adjustment section 200 adds or selects the audio signals of m channels and converts them into n playback channels, according to the specification from the reproduction channel sound image localization initial setting section 600. The phase and sound pressure level of the audio signal of each reproduction channel are adjusted, and the phase difference and sound pressure level difference between the reproduction channels are adjusted to produce n second frequency band speakers 28L,
Play from 28R.

The sound pressure level difference sound image localization adjustment unit 300 adds or selects the audio signals of m channels and converts them into n playback channels according to the specifications from the playback channel sound image localization initial setting unit 600. The sound pressure level of the audio signal of the channel is adjusted, and the sound pressure level difference between the reproduction channels is adjusted, and the audio signal is reproduced from the n third frequency band speakers 29L and 29R.

The high-frequency sound pressure level adjustment unit 400 generates a summed audio signal obtained by adding audio signals of m channels or a selection selected and extracted from m channels according to the specification from the reproduction channel sound image localization initial setting unit 600. The sound pressure level of the audio signal is adjusted, and the audio signal is reproduced from the fourth frequency band speaker 27.

As described above, the playback channel sound corps localization initial setting unit 600 includes specific setting data of the divided bands, sound pressure level values regarding the first or fourth frequency band, the value of n of the playback channel for m Heka channels, Phase values, sound pressure level values, etc. regarding the second or third frequency band are stored, and these values are transferred to each block upon initial setting of each block section.

FIG. 4 shows an application example of the multipoint video conference system of the present invention. Separate person video signals and audio signals are transferred from m points via the communication network 60 to the receiving terminal point 80 as m signals. The receiving terminal displays images of m people on a television screen and performs sound image localization control. This control [= in some cases, the first and fourth frequency bands 21.24
The audio of the second and fourth frequency bands 22.23 is played back by a single speaker 26.27, and the audio of the second and fourth frequency bands 22.23 is played back by multiple speakers (28LF, 29LF), (2
8RF, 29RF), (28LB, 29LB), (28
RB, 29RB).

In the case of m=n, the existing stereo sound of 2 channels, 3 channels, 4 channels, etc. can be divided into the 1st to 4th frequency bands and played from each speaker without adjusting the phase or sound pressure level. This invention also includes a video conference system and the like.

"Effects of the Invention" As explained above (-1) This invention (;According to the sound image localization reproduction method (:), the sound image localization reproduction method (:) divides the frequency band into a frequency band in which upward auditory perception occurs and the other frequency bands, and the sound in the former band is The sound image localization is controlled using multiple speakers, and the sound in the latter band is played back using a single speaker located close to the video part of the TV or other device without controlling the sound image localization, which results in poor direction perception. When reproducing audio in the first and fourth frequency bands that cannot be obtained, multiple speakers are not used, so the "blurring" of the sound due to multiple sound sources does not occur, and the second and third frequency bands allow direction perception to be obtained. This has the advantage that the accuracy of sound image localization can be improved.Also, since the audio in the first and fourth frequency bands, where direction perception cannot be obtained, is played back by a single speaker and placed close to the TV, the interaction with the video makes the appearance appear different. This has the advantage that it is easy to localize the sound image in the video area in a pseudo manner.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the features of this invention regarding frequency band division (: Fig. 2 is a block diagram showing an example of a reproduction system showing the features of this invention, and Fig. 3 is a block diagram showing the configuration of an embodiment of this invention. Figure 4 is a diagram showing an application example of the multipoint video conference system 1 of the present invention, and Figure 5 is a diagram showing various examples of a conventional sound image localization reproduction system for video conferences.

Claims (1)

[Claims] (1) A means for dividing a frequency band for each audio signal of a plurality of input channels to be subjected to sound image localization generation, and a means for outputting the divided first frequency band audio signal to a reproduction channel. means for adjusting the sound pressure level; and means for adjusting the audio signal of the divided second frequency band so that a phase difference (time difference) and a sound pressure level difference are generated between the reproduction channels in order to generate sound image localization. means for adjusting the phase and level; and means for adjusting the level so that a sound pressure level difference is generated between the reproduction channels in order to generate sound image localization for the audio signal of the divided third frequency band. , comprising means for setting correspondence data between the input channel and the reproduction channel and localization data that defines the sense of distance, sense of direction, etc. of sound image localization, and the second and second channels are provided with means for setting localization data, etc. that define the sense of distance, sense of direction, etc. of sound image localization, and the second and second The sound image localization is controlled using multiple speakers for the frequency band No. 3, and the above-mentioned No.
A sound image localization reproduction method characterized by using a single speaker for reproduction without performing sound image localization for the frequency band.