Sound processing unit

Details Sound processing unit Sound processing unit

1998-12-15

2001-01-09

Isen, Forester W. (Department: 2747)

Electrical audio signal processing systems and devices

Dereverberators

C381S151000, C381S057000, C379S406010, C379S413020

Reexamination Certificate

active

06173058

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sound processing unit in the transmitter/receiver set of a telephone, wireless equipment, and the like.
2. Description of the Related Art
Earphones and high-directionality microphones are used in conversations between a pilot and a pathfinder in an airport, and in conversations by telephones and wireless equipment in an environment with a high level of noises as a construction field.
However, when the noises are enormous, not only the voices of a persons to be transmitted, but the surrounding noises come in through the earphone and the microphone, so that the partner of the call finds it very difficult to catch the voice of the person transmitting.
In order to solve such a problem, earphone-mic equipment has been proposed, which has a function to detect the voices regardless of the surrounding noises, utilizing vibrations of the internal wall of the external auditory meatus generated when a person speaks, namely, bone conduction sound signals. This earphone-mic houses a vibration pick-up that detects the bone conduction sound signals, and a speaker in the ear piece. This earphone-mic is to be worn on the ear of a user, and is connected through signal lines to a transceiver or a portable telephone.
However, the vibration pick-up of this earphone-mic detects not only the bone conduction sound signals, but also the vibrations generated when the speaker emits sounds. In consequence, the vibrations are transmitted to the other party to the call as an echo, which reduces the quality of conversation.
However, the invention disclosed in the Japanese Patent:Laid-Open publication No. H8-340590 proposes an earphone-mic that suppresses such an echo and improves the quality of conversation. Concretely, this earphone-mic contains, in addition to a speaker and a vibration pick-up, a microphone to detect sounds that the speaker emits; and suppresses the echo in such a manner that a signal detected by the microphone is subtracted from a signal detected by the vibration pick-up.
Here, the level of a signal detected by the microphone is regulated to have the same level as a signal component detected by the vibration pick-up by a frequency equalizer circuit in each frequency band, and then, the signal detected by the microphone is inputted to a subtraction circuit.
However, the voice of the person transmitting is not only detected by the vibration pick-up, but also can be detected in part by the microphone for detecting the output sounds from the speaker. The subtraction of the signal detected by the microphone from the signal detected by the vibration pick-up involves an attenuation of a signal level corresponding to the voices of the person to transmit. This attenuation further increases by the regulation performed by the frequency equalizer circuit.
Further, the conventional earphone-mic that utilizes bone conduction sound signals has to be worn on the user's ear; and there are problems in wearing it and inconvenience in responding during reception.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing problems, and an object of the present invention is to provide a sound processing unit capable of removing the influence of noise in environments having an enormous noises.
In order to accomplish the foregoing object, the sound processing unit according to the invention is comprised of: a sound outputting means such as a (speaker) that outputs to the outside an input sound signal from a partner of a call as a voice of the partner of the call, a vibration detection means (such as a vibration pick-up) for detecting a bone conduction signal of a voice of a person to transmit, a first adaptive filter that estimates an echo component detected by the vibration detection means from an output of the sound outputting means on the basis of the input sound signal, and outputs a estimated-echo signal, a first adding means (first adder) that subtracts the estimated-echo signal from an output of the vibration detection means and outputs an estimated bone conduction sound signal, and a judgment means (such as a double talk detector) that judges if the input sound signal is silent or not and if the voice of the person to transmit is silent or not.


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