Transmitter-receiver having ear-piece type acoustic transducing part

• US 5,933,506 A
• Filed: 05/16/1995
• Issued: 08/03/1999
• Est. Priority Date: 05/18/1994
• Status: Expired due to Term

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Matsumoto, Kohichi, Yuse, Chikara, Mitsuhashi, Kazumasa, Matsui, Hiroyuki, Aoki, Shigeaki, Nishino, Yutaka
• Primary Examiner(s): Kuntz, Curtis A.
• Assistant Examiner(s): NGUYEN, DUC MINH
• Application Number:
  US08/441,988
• Time in Patent Office: 1,540 Days
• Field of Search: 381/92, 381/94, 381/98, 381/111, 381/122, 381/101, 381/102, 381/104, 381/119, 381/121, 381/151, 381/57, 381/94.1, 381/68.3, 381/68.6
• US Class Current: 381/151
• CPC Class Codes: H04R 1/46 Special adaptations for use as contact microphones, e.g. on musical instrument, on stethoscope throat mountings H04R1/14
• CPC Class Codes: H04R 2460/13 Hearing devices using bone conduction transducers
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

Ear-piece type acoustic transducing part is provided with a bone-conducted sound pickup microphone for picking up a bone-conducted sound, a directional microphone for picking up an air-conducted sound and an electro-acoustic transducer for transducing a received speech signal to a received speech sound. A transmitting-receiving circuit connected to the acoustic transducing part includes: a low-pass filter which permits the passage therethrough of low-frequency components in a bone-conducted sound signal from the bone-conducted sound pickup microphone; a high-pass filter which permits the passage therethrough of high-frequency components in an air-conducted sound signal from the directional microphone; first and second variable loss circuits which impart losses to the outputs from the low-pass filter and the high-pass filter, respectively; a comparison/control circuit which compares the output levels of the low-pass filter and the high-pass filter with predetermined first and second reference levels, respectively, and based on the results of comparison, controls losses that are set in the first and second variable loss circuits; and a combining circuit which combines the outputs from the first and second variable loss circuits into a speech sending signal.

Claims

1. A transmitter-receiver comprising:

acoustic transducing means composed of a bone-conducted sound pickup microphone for picking up a bone-conducted sound and for outputting a bone-conducted sound signal, a directional microphone for picking up an air-conducted sound and for outputting an air-conducted sound signal, and a receiver for transducing a received speech signal to a received speech sound;

a low-pass filter which permits the passage therethrough of those low-frequency components in said bone-conducted sound from said bone-conducted sound pickup microphone which are lower than a predetermined cutoff frequency;

a high-pass filter which permits the passage therethrough of those high-frequency components in said air-conducted sound from said directional microphone which are higher than said cutoff frequency;

first and second variable loss circuits which impart losses to the outputs from said low-pass filter and said high-pass filter;

a comparison/control circuit which compares the output levels of said low-pass filter and said high-pass filter with predetermined first and second reference levels and, based on the results of comparison, controls the losses that are set in said first and second variable loss circuits;

a combining circuit which combines the outputs from said first and second variable loss circuits and outputs a speech sending signal; and

means for supplying said received speech signal to said receiver.

2. The transmitter-receiver of claim 1, wherein said acoustic transducing means includes an omnidirectional microphone for detecting noise components, and which further comprises a noise suppressing part which combines the outputs from said directional microphone and said omnidirectional microphone to suppress said noise components and supplies said high-pass filter with said noise component suppressed output.

4. The transmitter-receiver of claim 1, which further comprises:

third and fourth variable loss circuits connected to the output side of said combining circuit and the input side of said received speech signal supplying means, for controlling the levels of said speech sending signal and said received speech signal, respectively; and

a second comparison/control circuit which compares the level of said speech sending signal to be fed to said third variable loss circuit and the level of said received speech signal to be fed to said fourth variable loss circuit with predetermined third and fourth reference levels, respectively, and on the basis of the results of comparison, controls the losses that are set in said third and fourth variable loss circuits.

5. The transmitter-receiver of claim 2 or 3, wherein said noise suppressing part comprises:

a first amplifier for amplifying said air-conducted sound signal from said directional microphone;

a second amplifier for amplifying said noise components from said omnidirectional microphone; and

a noise suppressor circuit which adds together the outputs from said first and second amplifiers in a 180°

out-of-phase relation to each other to generate an air-conducted sound signal with said noise components suppressed and applies it to said high-pass filter.

3. A transmitter-receiver comprising:

acoustic transducing means composed of a bone-conducted sound pickup microphone for picking up a bone-conducted sound, a directional microphone for picking up an air-conducted sound, an omnidirectional microphone for detecting noise, and a receiver for transducing a received speech signal to a received speech sound;

a low-pass filter which permits the passage therethrough of those low-frequency components in the output from said bone-conducted sound pickup microphone which are lower than a predetermined cutoff frequency;

a noise suppressing part which combines the outputs from said directional microphone and said omnidirectional microphone to suppress a noise component;

a high-pass filter which permits the passage therethrough of those high-frequency components in the output from said noise suppressing part which are higher than said cutoff frequency;

a combining circuit which mixes the outputs from said low-pass filter and said high-pass filter and outputs a speech sending signal; and

means for supplying said received speech signal to said receiver.

6. A transmitter-receiver comprising:

acoustic transmitting means composed of a bone-conducted sound pickup microphone for picking up a bone-conducted sound and for outputting a bone-conducted sound signal, air-conducted sound pickup microphone means for picking up an air-conducted sound and for outputting an air-conducted sound signal, and a receiver for transducing a received speech signal to a received speech;

comparison/control means which estimates a level of ambient noise, compares said estimated level with a predetermined threshold level and generates a control signal on the basis of the results of comparison; and

speech sending signal generating means which responds to said control signal to control additive mixing of said air-conducted sound signal from said air-conducted sound pickup microphone means and said bone-conducted sound signal from said bone-conducted sound pickup microphone to generate a speech sending signal;

wherein said comparison/control means generates, as said control signal, a signal indicating whether said estimated noise level is higher or lower than said threshold level;

said speech sending signal generating means includes signal select means responsive to said control means to select either one of said bone-conducted sound signal and said air-conducted sound signal; and

said speech sending signal generating means generates said speech sending signal from said selected signal.

8. The transmitter-receiver of claim 6, or 7 wherein said comparison/control means includes means for holding a relationship between the ambient noise level and at least the level of said air-conducted sound signal in non-talking states;

and said comparison/control means is a means which obtains, as said estimated noise level, a noise level corresponding to the level of the air-conducted sound signal during the use of said transmitter-receiver based on said relationship, compares said estimated noise level with said threshold level and generates said control signal on the basis of the result of comparison.

9. The transmitter-receiver of claim 8, wherein said relationship is the relationship between the ambient noise level and the level ratio of said bone-conducted sound signal versus said air-conducted sound signal;

and said comparison/control means includes means which obtains a level ratio between said bone-conducted sound signal and said air-conducted sound signal and obtains the noise level corresponding to said level ratio, as said estimated noise level, from said relationship.

10. The transmitter-receiver of claim 6 or 7, wherein said comparison/control means includes means for holding a relationship between the ambient noise level and at least the level of the air-conducted sound signal in a talking state;

and said comparison/control means is a means which obtains, as said estimated noise level, a noise level corresponding to the level of said air-conducted sound signal during the use of said transmitter-receiver based on said relationship, compares said estimated noise level with said threshold value and generates said control signal on the basis of the result of comparison.

11. The transmitter-receiver of claim 10, wherein said relationship is the relationship between the ambient noise level and the ratio of bone-conducted sound signal level versus air-conducted sound signal level;

and said comparison/control means includes means which obtains a level ratio between said bone-conducted sound signal and said air-conducted sound signal and obtains the noise level corresponding to said level ratio, as said estimated noise level, from said relationship.

12. The transmitter-receiver of claim 6 or 7, wherein said comparison/control means includes means for holding a first relationship between the ambient noise level and at least the level of said air-conducted sound signal in non-talking states and a second relationship between the ambient noise level and at least the level of said air-conducted sound signal in a talking state;

and said comparison/control means is a means which compares the level of said received speech signal and at least one of the level of said air-conducted sound signal and the level of said bone-conducted sound signal with predetermined first and second reference level values, respectively, to determine if said transmitter-receiver is in a talking or listening state, and on the basis of said first or second relationship corresponding to the results of comparison, obtains, as said estimated noise level, a noise level corresponding to at least said air-conducted sound signal, compares said estimated noise level with said threshold value, and generates said control signal on the basis of the result of comparison.

13. The transmitter-receiver of claim 12, wherein said first and second relationships are relationships between the ambient noise level and the level ratio of said bone-conducted sound signal versus said air-conducted sound signal in a non-talking state and in a talking state, respectively;

and said comparison/control means includes means which obtains the level ratio between said bone-conducted sound signal and said air-conducted sound signal and obtains the estimated noise level corresponding to said level ratio from either one of said first and second relationships.

14. The transmitter-receiver of claim 6 or 7 which further comprises first and second signal dividing means for dividing each of at least said air-conducted sound signal and said bone-conducted sound sending signal into a plurality of frequency bands;

said speech sending signal generating means comprises a plurality of signal mixing circuits each of which is supplied with said air-conducted sound signal and said bone-conducted sound signal of the corresponding frequency band from said first and second signal dividing means, then mixes them in accordance with a band control signal and outputs the mixed signal, and a signal combining circuit which combines the outputs from said plurality of signal mixing circuits and outputs the combined signal as said speech sending signal; and

said comparison/control means is a means which is supplied with at least said air-conducted sound signals of the corresponding frequency bands from said first signal dividing means, estimates ambient noise levels of said frequency bands from said air-conducted sound signals, compares said estimated noise levels with a plurality of threshold values predetermined for said plurality of frequency bands, respectively, and generates band control signals on the basis of the results of comparison.

15. The transmitter-receiver of claim 14, wherein said comparison/control means includes means for holding a relationship between said ambient noise levels in said plurality of frequency bands in non-talking states and at least the levels of said air-conducted sound signals of the corresponding frequency bands;

and said comparison/control means is a means which obtains, as said estimated noise level of each frequency band, a noise level corresponding to the level of the air-conducted sound signal during the use of said transmitter-receiver based on said relationship, compares said estimated noise level with said threshold value, and generates said band control signal of said each frequency band on the basis of the result of comparison.

16. The transmitter-receiver of claim 15, wherein said relationship is the relationship between the ambient noise level and the level ratio of said bone-conducted sound signal versus said air-conducted sound signal in each frequency band in non-talking states;

and said comparison/control means includes means which obtains a level ratio between said bone-conducted sound signal and said air-conducted sound signal in each frequency band and obtains the noise level corresponding to said level ratio, as said estimated noise level of said each frequency band, from said relationship.

17. The transmitter-receiver of claim 14, wherein said comparison/control means includes means for holding a relationship between ambient noise levels in said plurality of frequency bands and at least levels of said air-conducted sound signals of the corresponding frequency bands in talking states;

and said comparison/control means is a means which obtains, as said estimated noise level of each frequency band, a noise level corresponding to the level of the air-conducted sound signal during the use of said transmitter-receiver based on said relationship, compares said estimated noise level with said threshold value, and generates said band control signal of said each frequency band on the basis of the result of comparison.

18. The transmitter-receiver of claim 17, wherein said relationship is the relationship between the ambient noise level and the level ratio of said bone-conducted sound signal versus said air-conducted sound signal for each frequency band in said talking states;

and said comparison/control means includes means which obtains a level ratio between said bone-conducted sound signal and said air-conducted sound signal for each frequency band, and obtains the noise level corresponding to said level ratio, as said estimated noise level of said each frequency band, from said relationship.

19. The transmitter-receiver assembly of claim 14, wherein said comparison/control means includes means for holding a first relationship between the ambient noise level and at least the level of said air-conducted sound signal in each corresponding frequency band in non-talking states and a second relationship between the ambient noise level and at least the level of said air-conducted sound signal in a talking state;

and said comparison/control means is a means which compares the level of said received speech signal and at least one of the level of said air-conducted sound signal and the level of said bone-conducted sound signal in each frequency band with predetermined first and second reference level values, respectively, for said frequency band to determine if said transmitter-receiver is in a talking or listening state, and on the basis of said first or second relationship corresponding to the result of determination, obtains, as said estimated noise level, a noise level corresponding to at least the level of said air-conducted sound signal, compares said estimated noise level with said threshold value, and generates said control signal of said each frequency band on the basis of the result of comparison.

20. The transmitter-receiver of claim 19, wherein said first and second relationships for each frequency band between the ambient noise level and the level ratio of said bone-conducted sound signal versus said air-conducted sound signal in a non-talking state and in a talking state, respectively;

and said comparison/control means includes means which obtains the level ratio between said bone-conducted sound signal and said air-conducted sound signal for each frequency band and obtains the estimated noise level corresponding to said level ratio from either one of said first and second relationships.

21. The transmitter-receiver of claim 6 or 7, which further includes a directional microphone and an omnidirectional microphone as said air-conducted sound pickup microphone and noise suppressing means, said noise suppressing means being a means which, during a silent state and a listening state, outputs a signal from said omnidirectional microphone as said air-conducted sound signal representing a noise signal and, during a talking state, combines signals from said directional microphone and said omnidirectional microphone and outputs said combined signal as said air-conducted sound signal with noise suppressed.

7. A transmitter-receiver comprising:

acoustic transmitting means composed of a bone-conducted sound pickup microphone for picking up a bone-conducted sound and for outputting a bone-conducted sound signal, air-conducted sound pickup microphone means for picking up an air-conducted sound and for outputting an air-conducted sound signal, and a receiver for transducing a received speech signal to a received speech;

comparison/control means which estimates a level of ambient noise, compares said estimated level with a predetermined threshold level and generates a control signal on the basis of the results of comparison; and

speech sending signal generating means which responds to said control signal to control additive mixing of said air-conducted sound signal from said air-conducted sound pickup microphone means and said bone-conducted sound signal from said bone-conducted sound pickup microphone to generate a speech sending signal;

wherein said comparison/control means is a means which, when said estimated noise level is within an area of a fixed width defined about said threshold level, supplies said speech sending signal generating means with a control signal for mixing said air-conducted sound signal and said bone-conducted sound signal at a ratio corresponding to said estimated noise level; and

said speech sending signal generating means includes a means responsive to said control signal to mix said air-conducted sound signal and said bone-conducted sound signal at said ratio.