JP2523366B2 - Audio playback method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a voice reproduction system used in a communication conference system, for example.

“Conventional technology” When implementing communication conference systems such as voice conferences and video conferences, the playback device is often used for a long time due to the nature of the conference, and using a handset or earphones puts a heavy burden on the listener. The first problem of causing a feeling of pressure and a feeling of pressure occurs.

On the other hand, a method of using a loudspeaker without using a receiver or earphones is conceivable, but in this case, there arises a drawback that is not regarded as a problem with the receivers or earphones. That is, when a communication conference is held in an environment in which people (non-parties) unrelated to the conference are present, a second problem arises in that the content of the reproduced conference is heard by the non-party.

In order to deal with this point, a reproduction method in which the loud speaker has narrow directivity is considered. It takes advantage of the fact that if only the parties are located within the listening range reduced by the narrow directivity, it is difficult for non-parties who are unrelated to the conference to listen. However, with this conventional method, it is difficult to realize directivity in the low sound range where the wavelength of sound is large, and if it is forcibly realized, the speaker aperture becomes large and the device becomes large.

In order to solve this problem, a narrow directional speaker is used for the frequency band that affects the intelligibility of the conversation (for example, formant frequency band), and an omnidirectional speaker is used for the other frequency bands. The method of doing is proposed. The present invention improves this method and further reduces the intelligibility of the conversation contents to the concerned non-parties in the surroundings, that is, prevents the leakage of the conversation contents to the surroundings.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks.
Non-directed masking sound to reduce the intelligibility of the conversation content to the surrounding non-parties by utilizing the masking effect by playing with narrow directivity to the frequency band that affects the intelligibility of the conversation content. The purpose of the present invention is to provide a sound reproduction method of reproducing with a sex speaker.

"Means for Solving the Problem" The present invention divides a frequency band into two parts according to the degree of affecting the intelligibility of conversation content, and narrows the directivity of a voice in a frequency band (directional frequency band) that affects the intelligibility. An omnidirectional speaker that is synthesized by adding a masking sound for masking the sound reproduced from the narrow directional speaker to a sound in a frequency band (omnidirectional frequency band) that is reproduced by a speaker and does not affect the intelligibility. Playing in is the most important feature. The frequency bands that affect the intelligibility of the conversation include the frequency band of formants, which are the component sounds that characterize the Japanese 5 vowels, and the frequency band that allows individual discrimination.

"Embodiment" FIG. 1 is a first system example showing the features of the present invention. Monaural sound X (=
A + B) audio signal is frequency-divided by the frequency division circuit 11 (division between A and B), and for example, the voice A of the formant frequency of interest (including frequencies in the vicinity thereof) is output by the directional speaker 12. Playback is performed, and the voice B having other frequencies is transferred to the masking sound adding unit 25. The masking sound addition unit 25 adds the “masking sound C for A” transferred from the masking sound input terminal 15 to the sound B, and reproduces this synthesized sound (B + C) from the omnidirectional speaker 13. The masking sound C is, for example, another voice similar to the voice A.

The directional speaker 12 has a role of allowing the non-parties 14 in the surroundings to hear (without being understood) the surrounding non-parties 14 and the parties 15, and the omnidirectional speaker 13 has a feeling of sound spread and thickness. It has a role to issue etc. That is, the party 15 is a speaker
Audio played from 12 and speaker 13 X + C (= A + B +
C) and the non-party 14 listens to the voice B + C reproduced from the speaker 13 to appropriately control the volume of the masking sound C, thereby reducing the intelligibility of the conversation content of the party 15 to the non-party 14. Can be done.

FIG. 2 is a second system example showing the features of the present invention. With respect to the stereo audio signals (L signal, R signal) transferred from the input terminal 10, the L signal and the R signal are, for example, the voice in the formant frequency band and the voice according to the reproduction operation described in FIG. The voice of the former is reproduced by the directional speaker 12L for the L signal and the directional speaker 12R of the R signal respectively, and the voice of the latter (L signal, R signal) is divided into the masking sound. It is transferred to the addition unit 25. The masking sound adding unit synthesizes the masking stereo sound transferred from the masking sound input terminal 15 and the stereo sound transferred from the frequency division circuit 11 for each corresponding L signal and R signal, and synthesizes this synthesized sound. The reproduction is performed from the L signal omnidirectional speaker 13L and the R signal omnidirectional speaker 13R, respectively. The parties 15 can hear the conversation content by sound localization.

In the conventional technology, since the directivity is given to the entire frequency band, the speaker tends to be large, but in the present invention, the directivity is increased with respect to the frequency band that affects the intelligibility of the conversation content, Furthermore, the point that the intelligibility effect is enhanced by utilizing the masking effect is a big difference from the conventional one.

FIG. 3 is a block diagram showing the configuration of the embodiment of the present invention. In response to a command from the control unit 24, the frequency band setting unit 33,
The directional band setting data and the omnidirectional band setting data, which are predetermined in consideration of a male voice, a female voice, a sound effect of conversation, etc., are respectively input to the directional band extracting / reproducing unit 21 and the omnidirectional band extracting / reproducing unit 22. Forward. The directional band extracting / reproducing unit 21 performs initial setting based on the directional band setting data, and transfers the completion notification to the frequency band setting unit 23 after the establishment is completed. At the same time, the omnidirectional band extraction / reproduction unit 22 performs initial setting based on the omnidirectional band setting data, and after completion of the setting, transfers the completion notification to the frequency band setting unit 23. The frequency band setting unit 23 receives the completion notification received from the directional band extraction / playback unit 21 and the completion notification received from the omnidirectional band extraction / playback unit 22, and then issues a start command to the directional band extraction / playback unit. 21 and omnidirectional band extraction / playback unit 22
And notify. After the notification is completed, the directional band extraction / playback unit
Reference numeral 21 extracts only the band of the voice that is initially set for the audio signal sent from the input terminal 10, and reproduces the voice through the directional speaker 12. On the other hand, the omnidirectional band extraction / reproduction unit 22 extracts only the initially set voice and transfers the voice to the masking sound addition unit 25. The masking sound adding unit 25 adds the masking sound input from the masking sound input terminal 15 to the voice transferred from the omnidirectional band extraction reproducing unit 22, synthesizes the synthesized sound, and the synthesized sound is generated by the omnidirectional speaker 13 To play through.

[Advantages of the Invention] As described above, according to the voice reproduction method of the present invention, a directional speaker is provided for voices in the formant frequency band (including frequencies in the vicinity thereof) that affect the intelligibility of conversation content. The listener is hands-free because the sound is played back through the voice, the masking sound is added to the sound in other frequency bands, and the synthesized sound is played back through the omnidirectional speaker. In addition to the advantage, the masking effect has the advantage that the conversation content can be heard only by the parties and not by the non-parties around. Furthermore, instead of giving directivity to all frequencies of 100 Hz to 8000 Hz in the human generation range, 300 Hz to 200 in the middle range
Since directivity is given only to some frequency bands of 0 Hz, there is an advantage that the speaker (speaker diameter) can be downsized and the economy can be achieved. There is also an advantage in that the use of an omnidirectional speaker can provide a feeling of sound spread and a feeling of thickness.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first system example showing the features of the present invention, FIG. 2 is a block diagram showing a second system example showing the features of the present invention, and FIG. 3 is an embodiment of the present invention. It is a block diagram which shows a structure.

Claims (1)

(57) [Claims] 1. A voice reproduction system having a directional speaker having directivity and an omnidirectional speaker having omnidirectionality, wherein directivity is provided when reproducing an input audio signal. Means for setting a directional frequency band and an omnidirectional frequency band having no directivity, and means for extracting an audio signal in the directional frequency band from the input audio signal and reproducing the audio signal using the directional speaker. Means for extracting the audio signal in the omnidirectional frequency band from the input audio signal, and an audio signal for masking the audio signal in the directional frequency band added to the audio signal in the omnidirectional frequency band, And a means for reproducing using a directional speaker.