Nec Corporation

Michitaka Sisido

Toshio Yoshida

An arrangement for noise removal according to the present invention includes a microphone and an acoustic high-pass filter positioned in front of the microphone and consisting of the combination of an acoustic resistance, an acoustic compliance and an inertance. According to the invention, the acoustic resistance is composed of nonwoven fabric; the acoustic compliance, of a cavity; and the inertance, of a thin cavity connected to said cavity. This acoustic high-pass filter reduces unpleasant noise which arises from the microphone when a low-frequency high-pressure air stream, such as the speaker's breath, hits the mouthpiece of the telephone.

Noise removing apparatus using a microphone

In a telephone set having a receiver (42) and a loudspeaker (39), a switch circuit (37) selects supply of a reception speech signal, transmitted from a counterpart section (60), to the receiver or the loudspeaker in response to a selection signal. A first adaptive echo canceller (43a) produces a pseudo echo signal with reference to the reception speech signal. A controller (44) controls operation of the first adaptive echo canceller in response to the selection signal to optimize the pseudo echo signal. A first digital adder (35a) carries out a particular calculation between the pseudo echo signal and a transmission speech signal, relating to the transmission sound supplied to a microphone (46). The adder produces a particular calculation result signal representative of a result of the particular calculation. In accordance with the particular calculation result signal, a transmission is carried out towards the counterpart section.

Telephone set in which an echo signal is effectively cancelled in spite

When display control for a display device installed in a vehicular cabin is to be performed, an environmental light intensity is detected by a light sensor, and variation time function of the environmental light intensity is calculated. On the basis of the light intensity variation time function, a variation time function of a human pupil open degree is predicted. On the basis of the predicted time function, an optimal value of brightness of the display device is determined to perform display brightness control.

Display control device for controlling brightness of a display installed

A telephone set comprises a noise detector, a noise level determining circuit, and a noise canceler. The noise detector detects a noise component from a transmitting acoustic signal by detecting signal recurrence of the transmitting acoustic signal. The noise level determining circuit determines a noise level by comparing the noise component with a first threshold. According to the noise level, the noise canoelet cancels the noise component from the transmitting acoustic signal when the noise level is not smaller than the first threshold. The telephone set further comprises a frequency characteristics controller for a received acoustic signal to obtain a desired speech articulation. The frequency characteristics controller, based on the noise level, determines a level change region, a level change value, and a level change direction of the spectrum of the received acoustic signal.

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Tokyo, Japan

Michitaka Sisido