JP2835009B2 - Bone and air conduction combined ear microphone device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bone conduction / conduction combined ear microphone device having a function of combining and outputting both detection outputs of bone conduction sound and air conduction sound.

[0002]

2. Description of the Related Art When a human utters, vocal cord vibrations and air vibrations in the oral cavity and nasal cavity are transmitted as bone-conducted sounds to the external auditory canal wall. Therefore, if the vibration pickup is pressed against the wall of the ear canal, the vibration accompanying the utterance can be detected as an audio signal. This is a bone conduction microphone. In addition, the air-conducted sound is that acoustic waves accompanying the utterance are emitted from the mouth into the air. Therefore, if the microphone is arranged near the ear, the air conduction sound can be detected as a sound signal. This is called an air conduction microphone. Here, bone-conducted voice has the characteristic that the attenuation of high-frequency components is large, so the clarity is not good. However, since the vibration of the ear canal wall is detected, the effect of external noise is low. is there. On the other hand, air-conducted speech has good clarity because it has the characteristic that the attenuation of high-frequency components is small, but has the disadvantage that it is easily affected by external noise because it detects air vibration waves in the outside world. is there.

[0003]

In consideration of such characteristics of the bone-conducted voice and the air-conducted voice, the bone-conducted output uses a low-pass filter to extract only low-frequency components and uses high-frequency components having poor sound quality. In order to avoid the use of high-pass components in the air-conduction output and to avoid using low-noise components with much noise, the output of each filter is synthesized at an appropriate ratio. A proposal has been made to secure good clarity while preventing the influence of noise (see Japanese Patent Application Laid-Open No. 6-30490). However, this prior art merely shows a structure in which both outputs are combined, and only shows an example in which an adjustment valve for adjusting the amount of air acting on the air-conducting microphone is used for adjusting the mixing ratio. The mixing ratio is fixed during use. Therefore, the degree of clarity depends on the degree of external noise, and there is no guarantee that an appropriate mixing ratio is maintained during use.

The present invention provides a bone conduction / conduction combined type ear microphone device in which the mixing ratio of the bone conduction output component and the air conduction output component during use is appropriately maintained even under the fluctuation of external noise. The purpose is to do.

[0005]

To achieve this object, a bone conduction and air conduction combined type ear microphone device according to the present invention comprises a bone conduction output component from a bone conduction microphone and an air conduction output component from an air conduction microphone. A synthesis control circuit for synthesizing the external noise level, the synthesis control circuit having noise level measuring means for measuring an external noise level, and when the external noise level measured by the noise level measuring means is low, It is configured to increase the ratio of the air conduction output component to the conduction output component, and to reduce the ratio of the air conduction output component to the bone conduction output component when the measured external noise level is large. I have. The external noise level measuring means may be configured to extract the external noise level from a noise component included in the air conduction output component. Further, the synthesis control circuit includes:
When the measured external noise level is low, the levels of the bone conduction output component and the air conduction output component are set to be high, and when the measured external noise level is high, the bone conduction output component and the air conduction output component are high. Each level of the component can be configured to have a lower eye. Further, the noise level measuring means operates when the air conduction output is absent and the air conduction output is present, it is determined that there is no sound, and the air conduction output is regarded as a noise level. When both of the air conduction output and the air conduction output are present, it is determined that the apparatus is in the utterance state, the noise measurement is stopped, and the immediately preceding noise measurement data is retained.

[0006]

[Principle] In describing a specific example of the present invention, first, basic conditions (principle) of the present invention will be described. A feature of the present invention resides in that a noise level is sequentially measured, and a mixing ratio between a bone conduction output component and an air conduction output component is adaptively changed according to the noise level. The conditions of the mixing ratio are as follows. When the noise level is low, the ratio of the air conduction output component is increased, and the levels of the bone conduction output and the air conduction output are set higher. As a result, the sensitivity of transmission is increased, sufficient output is obtained even when speaking with a small voice, and sound quality is also improved. When the noise level is high, the ratio of the air conduction output component is reduced, and the levels of the bone conduction output and the air conduction output are low. Therefore, the sensitivity to noise is reduced in terms of the ratio and the output level, and the noise level is reduced.
However, in an environment where the external noise level is high, the utterance level is high, and a sufficient output can be obtained even if the sensitivity of transmission is low.

In order to measure noise sequentially, for example, the following conditions are used. Utilizing that bone conduction output has low sensitivity to external noise and air conduction output has high sensitivity to external noise, when there is no bone conduction output and there is air conduction output, it is determined that there is no speech and at that time, Is regarded as the noise level and the apparatus enters the noise measurement mode. When both the bone conduction output and the air conduction output are present, it is determined that the user is in the utterance state, and the noise measurement is stopped, and the immediately preceding noise measurement data is retained. In addition, when there is bone conduction output but no air conduction output, it means that rubbing noise is appearing, such as when the earphone is being inserted into the ear hole, and the noise measurement is also stopped at this time. The circuit that adjusts the ratio between the bone conduction component and the air conduction component is controlled based on the noise level measured as described above in accordance with the predetermined condition of the change in the mixing ratio.

[0008]

FIG. 1 is a block diagram showing an embodiment of the present invention. An ear microphone device A according to the present invention comprises an ear microphone main body (electroacoustic converter) 1 and a control circuit 2. The ear microphone body 1
The transmission system is a bone conduction microphone 11 and an air conduction microphone 12
The receiving side is provided with a receiving microphone 13. In the control circuit 2, the transmission amplifiers 21 and 22 for amplifying the output of the bone conduction microphone 11 detect excessive output such as rubbing noise in the output of the transmission amplifier 21 to insert a loss or reduce the amplifier gain. And a clipping circuit for preventing a subsequent amplifier from operating normally within the dynamic range, 23 is a band elimination filter by HPF or LPF, and 24 is a bone conduction output level. This is a gain adjuster for adjustment. 25 is a transmission amplifier for amplifying the output of the air conduction microphone 12, 26 is an HPF for attenuating noise included in the low range of the air conduction output, and 27 is for adjusting the level of the air conduction output. It is a gain adjuster. The outputs of the gain adjusters 24 and 27 are combined by the combiner 30 and transmitted from the transmission output terminal 31. Receiving input terminal 3
2 is transmitted to the earphone 13 for reception.

Reference numeral 28 compares the level of the output of the clipping circuit 22 with the output of the transmission amplifier 25, and controls the noise level estimating circuit 29 according to the comparison result.
4 and 27 are performed. Next, these operations will be described. The level comparison circuit 28 compares the output of the clipping circuit 22 with the output of the transmission amplifier 25, and the air conduction output obtained at the output of the transmission amplifier 25 is more constant than the bone conduction output obtained at the output of the clip circuit 22 ( For example, as shown in FIG. 2, when the output is higher than 20 dB), a comparison output for judging that there is no sound (noise) is output. The noise level estimating circuit 29 regards the output of the transmission amplifier 25 as noise only during the period when the comparison output is output from the level comparing circuit 28, measures the level thereof, and measures a certain averaging time constant (for example, 1 to 10). Second). In the utterance state where no comparison output is output, the obtained immediately preceding noise level is held as shown in FIG. In the gain adjusters 24 and 27, the following Table 1 is used in accordance with the noise level from the noise level estimation circuit 29.
Works like

[0010]

[Table 1] The noise level and the amount of gain change are adjusted and determined by constants. The operation state of the gain adjustment circuit in this case is as shown in FIG. 4, and the noise level is as shown in FIG.

Here, in addition to changing the gain of the air conduction amplifier system, control may be performed to change the cutoff frequency of the HPF 23 and the slope of the cutoff slope as shown in FIG. That is, when the noise is small, the air conduction component can be increased and the sound quality can be improved. However, when the noise is loud, the deterioration of the sound quality is tolerated to reduce the air-conducting component that easily picks up the noise, and conversely, the bone-conducting component that hardly picks up the noise is increased. By such processing, the total transmission level can be made substantially constant regardless of the level of noise. Further, as shown in FIG. 7, if the control is performed such that the gain of the bone conduction amplifier system is increased and the gain of the air conduction amplifier system is decreased at the same time, even when the apparatus is used in a noisy city area or the like, external control is performed. Since the audio frequency characteristic makes it difficult to pick up noise, it is possible to communicate with a small voice even if the noise is loud.

[0012]

As described above in detail, according to the present invention, the external noise level at the present time is substantially always measured, and the bone conduction voice and the air are mixed at a mixture ratio and level suitable for the measured external noise level. Since the synthesized voice can be synthesized with the guided voice, the synthesized voice obtained is a voice output with high clarity that greatly suppresses the influence of external noise, and a good voice level is maintained with a small voice even when the external noise is loud. Therefore, the practical effect of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining the operation of the present invention.

FIG. 3 is a characteristic diagram for explaining the operation of the present invention.

FIG. 4 is a characteristic diagram for explaining the operation of the present invention.

FIG. 5 is a characteristic diagram for explaining the operation of the present invention.

FIG. 6 is a characteristic diagram for explaining the operation of the present invention.

FIG. 7 is a characteristic diagram for explaining the operation of the present invention.

[Explanation of symbols]

 Reference Signs List 1 ear microphone main body 2 synthesis control circuit 11 bone conduction microphone 12 air conduction microphone 13 earphone for reception 21 transmission amplifier 22 clipping circuit 23 HPL / LPF 24 gain adjuster 25 transmission amplifier 26 HPF 27 gain adjuster 28 level comparison circuit 29 Noise level estimation circuit 30 Synthesizer 31 Output terminal 32 Input terminal

──────────────────────────────────────────────────続 き Continuation of front page (72) Kazumasa Mitsuhashi, Inventor Nippon Telegraph and Telephone Corporation, 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo (56) References JP-A-5-276587 (JP, A) 7-312634 (JP, A) JP-A-8-79868 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04R 1/00, 3/00

Claims (6)

(57) [Claims] 1. A synthesis control circuit for synthesizing a bone conduction output component from a bone conduction microphone and an air conduction output component from an air conduction microphone, wherein the synthesis control circuit measures an external noise level. And, when the external noise level measured by the noise level measuring means is small, the ratio of the air conduction output component to the bone conduction output component is increased, and when the measured external noise level is large, A bone conduction and air conduction combined-type ear microphone device configured to control to reduce a ratio of the air conduction output component to the bone conduction output component. 2. The apparatus according to claim 1, wherein the external noise level measuring means is configured to extract the external noise level from a noise component included in the air conduction output component.
2. The bone conduction / conduction combined type ear microphone device according to item 2. 3. The noise level measuring means operates when the bone conduction output is absent and the air conduction output is present, and determines that there is no speech and regards the air conduction output as a noise level. When both the bone conduction output and the air conduction output are present, it is determined that the state is a vocalization state, the noise measurement is stopped, and the immediately preceding noise measurement data is retained. The bone conduction / conduction combined type ear microphone device according to claim 1 or 2. 4. The synthesis control circuit sets each level of the bone conduction output component and the air conduction output component to a high level when the measured external noise level is low, and the measured external noise level is high. 4. The bone conduction and air conduction combined type ear microphone device according to claim 1, wherein each level of the bone conduction output component and the air conduction output component is sometimes set to a lower level. 5. The synthesizing control circuit suppresses the bone conduction output component when the external noise level increases,
The bone conduction / conduction combined type ear according to claim 1, 2, or 3, wherein the low cutoff frequency is shifted to a higher one without changing the level of the conduction output component. Microphone device. 6. The control circuit, wherein when the external noise level is increased, the level of the bone conduction output component is increased, while the level of the air conduction output component is decreased. 4. The bone conduction / conduction combined type ear microphone device according to claim 1, 2, or 3.