Abstract: A digitized input signal is sampled, to obtain a reference input signal. The reference input signal is spuriously whitened, to obtain a pseudo whitened signal. An echo replica signal is generated on the basis of the pseudo whitened signal and an adaptive filter coefficient. A cancellation error signal is obtained on the basis of an echo signal and the echo replica signal. The adaptive filter coefficient is updated on the basis of the cancellation error signal, the adaptive filter coefficient, and the pseudo whitened signal.

Abstract: An audio decoding device includes a playback speed change device for changing, with respect to a decoded audio signal obtained by a decoding device, the playback speed thereof; an output buffer for temporarily storing a digital audio signal outputted from the playback speed change device; a read out device for reading out the digital audio signals stored in the output buffer at predetermined time intervals; a playback speed control device for controlling the playback speed change device on the basis of the number of packets stored in the jitter buffer; and decoding timing control means for controlling the timing of decoding by the decoding device on the basis of the amount of data stored in the output buffer.

Abstract: A speech communication apparatus comprises voice speed conversion means for changing the time scale of a voice signal of a called party which arrives through a telephone line, and sidetone erasure means for erasing a sidetone signal.

Abstract: A periodic signal detector includes sample counting means for counting a number of samples between adjacent zero cross points in an input signal, the sample counting means outputting the number of samples between each time the number of samples between the adjacent zero cross points is obtained and continuing outputting the number of samples until a next zero cross point is detected, and periodic signal section detecting means for detecting a section, as a periodic signal section, in which the output from the sample counting means has a constant result.

Abstract: An object is to provide an arrangement which enables the worker to easily carry out checking and maintenance on a part such as an engine from outside in a natural pose without climbing on a counterweight. In a construction vehicle having a traveling vehicle body and a revolving superstructure with an implement, a counterweight installed in the rear of the revolving superstructure comprises a detachable, separable sub-counterweight which is located on the position corresponding to the position of a part requiring maintenance.

Abstract: A method of controlling an echo canceller for providing an echo cancellation signal by subtracting an echo replica signal either from a transmit signal or a receive signal. The method includes the steps of a first step of performing a speech detection based on the echo cancellation signal provided by the echo canceller; a second step of detecting a double talk condition based on a result of the speech detection performed by the first step; and a third step of controlling a learning operation of the echo canceller based on a result of the double talk detection performed by the second step.

Abstract: An object of the present invention is to provide an echo canceller capable of generating, when the double-talk detection precision is degraded and the learning of a filter coefficient swings by noises, an echo replica signal using a filter coefficient having a low degree of error at the time of detecting a double-talk state. A backup filter coefficient is calculated by adding a predetermined weighting factor times a filter coefficient obtained by the learning and a predetermined weighting factor times the preceding backup filter coefficient stored in second storage means.