JPS6228110Y2 - - Google Patents

Description

[Detailed description of the invention] [Description of the field to which the invention pertains] The present invention relates to a stereo loudspeaker telephone that achieves high quality reception by having two left and right reception speakers.

[Description of prior art]

Conventionally, in telephone communications, it has been common to use one channel for the signal system between opposing telephone sets. Therefore, conventional loudspeaker telephones use a single speaker to receive calls. In such reproduction using a single speaker, spatial reproduction of the sound field is impossible, so the following (1)
It was impossible to use the functions (3) to (3).

(1) directional perception of the sound source, (2) sense of distance to the sound source, and (3) sense of presence created by (1) and (2). Since it is not possible to reproduce a sufficient sound field, there is a drawback that high-quality audio cannot be realized using the effects (1) to (3) above.

Further, providing a sense of presence in the auditory effect by the phase difference and intensity difference between the two left and right speaker systems is known as the stereo recording and playback effect in general audio. However, in general stereo recording, playback, or stereo transmission, a recording, playback, or transmission system requires two channels, and the signals of each channel differ in phase and intensity even though they are signals from the same sound source. That is, in order to fully realize the stereo effect created by the phase difference and the intensity difference, the system from the transmitter to the receiver (speaker) requires two channels on each side. Therefore, with telephones in which the signal system between opposing telephones is one channel, it is either impossible to use the above-mentioned general audio technology, or there is a drawback that many channels (signal systems) are required. .

Furthermore, telephones equipped with two speakers are known (for example, Japanese Patent Application Laid-open No. 144306/1983).
However, there is a problem in that the above effects (1) to (3) cannot be obtained at all by simply connecting a single channel signal to two such speakers, rather than aiming at a stereo effect.

[Purpose of invention]

The present invention eliminates this drawback and makes all of the auditory abilities, including direction perception, sense of distance, and sense of presence, function, thereby realizing a state in which high-quality speech and other acoustic signals can be received.

The present invention will be explained in detail below.

[Explanation of the structure and action of the device]

FIG. 1 shows an embodiment of the present invention, in which 1 is a signal input terminal, 2 and 3 are phase shift circuits, 4 and 5 are control signal input terminals to the respective phase shift circuits, and 6 and 7 are amplifier circuits. , 8 and 9 are gain control signal input terminals of the respective amplifier circuits, and 10 and 11 are signal output terminals to both left and right receiving speakers.

Hereinafter, the operation of each part will be explained along with the configuration of the embodiment shown in FIG. An input signal sent from the signal input terminal 1 is branched to the left and right speaker systems, and becomes an input signal to the phase shift circuits 2 and 3. Phase shift circuit 2, 3
is a circuit that gives a time delay to the input signal,
This delay time is controlled by control signals from terminals 4 and 5 and changes over time. That is, the time delays τ ₁ , τ ₂ provided by the phase shift circuits 2 and 3
are each a function of time t, and τ ₁ = φ ₁
(t), τ ₂ =φ ₂ (t). and,
The control signals added to the terminals 4 and 5 are correlated with each other. For example, the phase difference Δτ between the signals of the left and right speaker systems generated by the phase shift circuits 2 and 3 is Δτ=φ ₁ (t) − φ ₂ It is set to vary from -τ ₀ to τ ₀ with a period fHz, as expressed by (t)=τ ₀ cos2πft. Phase shift circuit 2,
The output signal of 3 becomes the input signal of the amplifier circuits 6 and 7. The gains of the amplifier circuits 6 and 7 are controlled by control signals from terminals 8 and 9 and change over time. That is, if the gains of the amplifier circuits 6 and 7 are G ₁ and G ₂ , G ₁ and G ₂ are respectively expressed as functions of time t, and G ₁ = g ₁ (t), G ₂ = g ₂ ( t) by signals added to the control signal input terminals 8 and 9. There is a correlation between g ₁ (t) and g ₂ (t), and for example, the gain difference Δg between the left and right speaker systems caused by the amplifier circuits 6 and 7 is Δg=g ₁ (t)−g ₂ ( It is set to have a change from -g ₀ to g ₀ with a period f'Hz, as expressed by t)=g ₀ cos2πf't. Output signals 10 and 11 from the amplifier circuits 6 and 7 become input signals to the left and right receiving speakers, respectively.

As explained above, this embodiment uses a phase shift circuit,
It consists of an amplifier circuit.

The phase shift circuit and amplifier circuit provide a phase difference and an intensity difference to the left and right speaker system signals. These phase differences and intensity differences are known to play an important role in sound localization (Literature, Hearing and Psychoacoustics,
Acoustical Engineering Course 6, edited by the Acoustical Society of Japan, Chapter 12.6 pp.185~
195). Therefore, in the receiving state according to this embodiment, the sound image localization of the signal is performed in a certain direction depending on the phase difference Δ and the intensity difference ΔI. In addition, since Δ and ΔI vary slowly over time, the listener can perceive movement of the sound image accordingly. In this way, the sound image for a moving sound source is well localized, and the receiver can clearly perceive the movement of the sound image. As a result, the listening state can produce the same effect as a normal stereophonic listening state. That is, in such a receiving state, the effect of selective listening to signals in noise occurs, and as shown in FIG. 2, the clarity is about 20% better than in conventional mono-ear listening. Figure 2 shows the improvement in clarity in stereo listening;
This is a comparison of the intelligibility of monosyllabic words in stereo S and monaural M, using news reading of names as the background sound (Acoustic Engineering Course 6, Hearing and Psychoacoustics, p. 184).

[Explanation of effects]

As described above, according to the present invention, at least one of a phase shift circuit and an amplification circuit is provided in the input signal system of the two left and right receiver speakers, which branch the receiver input signal of one channel. It is possible to utilize all of the auditory abilities such as direction perception, sense of distance, and sense of presence to achieve a state of receiving high-quality speech and other acoustic signals.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention;
The figure is a curve diagram showing an example of clarity improvement characteristics in stereo listening. 1... Signal input terminal, 2, 3... Phase shift circuit,
4, 5... Phase shift control signal input terminal, 6, 7... Amplification circuit, 8, 9... Amplification gain control signal input terminal,
10, 11...Signal output terminals for left and right receiving speakers.

Claims (1)

[Scope of utility model registration request] The input signal is branched into two left and right signal systems each having a receiver speaker, and the left and right signal systems are
At least one circuit of a phase shift circuit and an amplifier circuit that generates a phase difference and an intensity difference between the left and right signal system signals and changes the phase difference and intensity difference over time. A stereo loudspeaker telephone set.