JPH02161897A - Portable electronic still sound device - Google Patents

Abstract

PURPOSE:To contrive the conversion to a still sound by constituting the device so that in a transmitter/receiver inserted into an external auditory meatus, a sound from a loudspeaker for leading a voice to the external auditory meatus side offsets an external sound which passes through the inside of this transmitter/receiver from the outside of the transmitter/receiver and led to the external auditory meatus. CONSTITUTION:The device is provided with a signal processing circuit 6 for generating an acoustic wave whose phase is opposite to at least an eminent sound in waves by which an external sound is propagated into an external auditory meatus against outputs of microphones 5a, 5b. In transmitter/receivers 4a, 4b inserted into the external auditory meatus, a sound from a loudspeaker for leading a sound to the external auditory meatus offsets an external sound which passes through the inside of this transmitter/receiver from the outside of the transmitter/receiver and lead to the external auditory meatus. Also, a place for this offset is in a roughly closed space such as the external auditory meatus. In such a way, a still sound effect is large, and also, the accuracy required technically can be obtained easily.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a portable electronic silent device, for example, a portable electronic silent device suitable for reducing the loudness of external noise at a low cost. be.

[Conventional technology]

Conventionally, in this type of portable electronic silent device, headphones are attached to a portable signal processing circuit and are pressed into contact with the right and left ears, respectively, and headphones are placed inside the hesodophone in approximately the same plane as the sounding body. The device is equipped with a microphone that detects sound to be transmitted into the ear canal.

The signal processing circuit inverts the amplitude of the sound signal detected by the microphone, shifts the phase by 180', and inputs the resulting sound signal to the handphone, thereby canceling out the sound propagated into the ear canal. This is what I am trying to do.

[Problem to be solved by the invention]

However, the portable electronic silent device described above is equipped with a microphone that detects sound to be propagated into the ear canal in substantially the same plane as the sounding body of the headphone.

Therefore, the sound from the headphones is input to the microphone, which tends to cause so-called howling.

The sound wave interference region caused by one sounding body is a three-dimensional space on the opposite side of the ear canal, that is, outside the headphones. Since this three-dimensional space is a wide space outside the ear canal, there is a problem that the sounds from two sound sources cannot be completely canceled out even if the amplitude of one of them is inverted and the phase is shifted by 180 degrees. However, it was not sufficient as a portable electronic silent device.

Therefore, the present invention has been made based on the above-mentioned circumstances, and its object is to provide a portable electronic silent device that can prevent howling.

Another object of the present invention is to provide a highly reliable portable electronic silent device that can completely cancel out external noise.

[Means to solve the problem]

In order to achieve such an object, the present invention basically includes a speaker that is shaped to be inserted into the external auditory canal and guides sound toward the external auditory canal, and an external speaker that is positioned on the back of the speaker and outside the external auditory canal. A transducer comprising a sound collecting microphone, and a signal processing circuit that generates a sound wave having a phase opposite to at least the predominant sound among the waves in which external sound propagates in the external auditory canal in response to the output of the microphone. This is a portable electronic silent device featuring the following.

[Effect]

In the portable electronic silent device configured in this way, in the transducer inserted into the ear canal, the sound from the speaker that guides sound to the ear canal side passes through the transducer from outside the transducer. This cancels out external sounds that are led to the ear canal side.

Since the location where this offset is performed is within the almost sealed space of the external auditory canal, the effect of reducing noise is significant and the accuracy required from a technical standpoint can be easily obtained.

Furthermore, according to the above configuration, the directional side of the output sound from the speaker and the directional side of the output sound to the microphone are in the same direction, that is, they are positioned with their backs facing each other. The amount of sound input from the microphone to the microphone is reduced, thus making it possible to prevent howling.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a portable electronic silent device according to the present invention will be described below with reference to the drawings.

First, in FIG. 1, there are earphones 4a and 4b, which are speakers, for the left and right ears, respectively, and microphones 5a and 5b, which are in contact with the backs of the earphones 4a and 4b, and are almost housed in the pinnae 1a, lb. The signal cables from the microphone 5b and the earphone 4b and the signal cables from the left ear microphone 5a and the earphone 4a are bundled into one cable 13 and connected to the signal processing circuit 6 stored in the left chest pocket 12. has been done. On the other hand, the output cable 17 of the background sound reproduction device 18 stored in the right chest pocket 13 is connected to the signal processing circuit 6.

Here, the signal processing circuit u6 has an appearance as shown in FIG. 2, and has input/output signal cables 13 from the left and right transmitters and an output signal cable from the background sound reproduction device at its side ends. 17 are connected.

In addition, on the outer surface, the battery power source of the signal processing circuit 6 is turned on.
-off switching switch 19 further includes volume switches 15 and 1 for adjusting the amplitude and phase of the opposite phase additional signal.
6. Furthermore, volume switch 2 for adjusting the volume of background sound
0. A volume switch 14 for setting the center frequency of the identification filter is attached.

Next, FIG. 3 shows the circuitry within the signal processing circuit 6 together with the earphone 4b and microphone 5b on the right ear side. In the figure, the earphone 4b
is a commercially available consumer product, which wraps the diaphragm 11b,
It has a structure in which a part of the sound wave emitting part is open. The outer diameter of the tip 12b of the earphone 4b is approximately equal to the inner diameter of the external auditory canal 2.

For this reason, the diaphragm 11b of the earphone and this tip 12
Since a closed space is formed by earphone 4b, ear canal 2, and eardrum 3, the sound waves from earphone 4b are attenuated and sent to microphone 5.
Howling can be prevented by being transmitted to the b side. The microphone 5b is a consumer-use condenser microphone and is inexpensive.

It is designed to be smaller. The output signal of this microphone 5b is sent to the signal processing circuit 6 described above. This circuit 6 consists of two systems, one for the right ear and one for the left ear (not shown).

Since the left ear and right ear systems are basically the same, only one system will be explained.

The output signal of the microphone 5b is first guided to a prominent person identification filter in the circuit 6, so that only the loudest persons are extracted from the external noise. This filter 7 is a bandpass filter, and its center frequency can be set with a volume 14 shown in FIG. For example, if a switched capacity filter is used as this filter, the number of clock pulses can be changed in proportion to the rotation angle of the volume 14, and stable and good passband characteristics can be easily obtained.

Next, within the phase inversion circuit 8, the output signal of this filter 7 and
Signals having a phase difference of 180° can be obtained. This circuit is composed of, for example, an operational amplifier, which is an IC circuit, and a resistor. Incidentally, the phase of the external sound changes in accordance with the spatial distance difference between the microphone 5b and the entrance of the external auditory canal 2. Therefore, in order to effectively muffle the sound, this amount of phase change must also be compensated for.
This magnitude depends on the center frequency of the outstanding person identification filter 7. Therefore, it is known that if the speed of sound C9 frequency f, the wavelength λ, and the above-mentioned distance difference are ΔL, this phase difference ΔT is determined from the following equation (1).

Here, ΔL is almost determined only by the transducer. On the other hand, the sound speed C is a function of the room temperature, but it is proportional to the square root of the absolute temperature. Considering that the amount of temperature change during use is generally small, the amount of change in the sound speed C is not large, and as a result, the phase difference Δψ becomes proportional to frequency. The phase adjustment circuit 9 having this characteristic can be realized by an analog element consisting of a coil and a resistor, for example. Furthermore, the amount of phase adjustment can be set by changing the resistance value corresponding to the rotation angle of the volume 15 shown in FIG. Furthermore, the amplitude can be easily adjusted by adjusting the volume 16 corresponding to the amount of change in the constant of the resistor externally attached to the operational amplifier. As mentioned above, this amplitude and phase difference are
Since it is generated during the sound wave propagation process between the microphone 5b and the microphone 5b, it is determined by the center frequency and sound speed of the transducer and identification filter.

Of these, the amount determined by the transducer is:

Adjustments can be completed before the device is shipped. On the other hand, the amount due to frequency and sound speed is determined by listening to only external noise and extracting characteristic noise, i.e., the dominant noise, at volume 14.
Volumes 15 and 16 can be set to minimize this size. The adder circuit 10 in the signal processing circuit 6 combines the outstanding signal and the output signal 1 from the background music player 18.
7 is added, and this signal is emitted from the earphones as a sound wave.

The background music player 18 is composed of, for example, a tape recorder, and the number of songs is selected according to the preference of the person using the portable electronic silent device.

In this embodiment, the background music is actively used to obtain the psychological masking effect, but basically, the effect of reducing the loudness of the noise can be achieved even without the background music.

Further, the signal processing circuit 6 and the reproduction device 17 are stored in pockets 12 and 13 of the jacket, but the storage location is not particularly limited. For example, a method of holding the device over the head is also included in the present invention.

Furthermore, it goes without saying that the portable electronic silent device according to the present invention may also be equipped with hearing aid means for amplifying the output from the microphones 5a, 5b and inputting it to the earphones 4a, 4b by switching.

[Effects of the Invention] As explained above, according to the portable electronic silent device according to the present invention, in the transducer inserted into the external auditory canal, the sound from the speaker that guides sound to the external auditory canal is transmitted through the transducer and the transducer. This cancels out external sounds that pass through the transducer and are guided to the external auditory canal.

Since the location where this offset is performed is within the almost sealed space of the external auditory canal, the effect of reducing noise is significant and the accuracy required from a technical standpoint can be easily obtained.

Furthermore, since the directional side of the output sound from the speaker and the directional side of the output sound to the microphone are in the same direction, that is, they are positioned with their backs facing each other, the sound from the speaker is input to the microphone. The amount is reduced and therefore the housing can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an embodiment diagram showing the handling of a portable electronic silent device according to the present invention, and FIG. 2 is an embodiment diagram showing the appearance of a signal processing circuit of the portable electronic silent device. FIG. 3 is a block diagram showing one embodiment of the signal processing circuit. 1 a, 1 b... auricular pinna, 4 a, 4 b... earphones, 5 a, 5 b... microphone, 6... signal processing circuit, 18... background music reproducing device. Figure 1

Claims (1)

[Claims] 1. Wave transmission and reception consisting of a speaker shaped to be inserted into the external auditory canal and guiding sound to the external auditory canal, and a microphone for collecting external sound located on the back of the speaker and outside the external auditory canal. and a signal processing circuit that generates a sound wave having a phase opposite to at least a predominant sound among the waves in which external sound propagates in the ear canal in response to the output of the microphone. . 2. The portable electronic silent device according to claim 1, wherein the signal processing circuit supplies a sound different from external sound from a speaker by switching. 3. The portable electronic silent device according to claim 1, comprising the signal processing circuit in which the output of the microphone is input to the speaker via a filter that passes only sounds in a specific frequency band, and an amplitude and phase adjustment circuit. 4. A portable electronic silent device according to claim 3, comprising means for adjusting the frequency band of sound passed through the filter. 5. The portable electronic silent device according to claim 3, wherein the amplitude and phase adjustment circuit is provided with means for adjusting the amplitude and phase. 6. In claim 2, the sound different from the external sound is
A portable electronic silent device that produces sound based on pre-stored electrical signals. 7. The portable electronic silent device according to claim 1, comprising hearing aid means for amplifying the output from the microphone and inputting it to the speaker by switching.