Showing papers by "Futoshi Asano published in 1994"

Hearing aid howling suppression by adaptive feedback cancellation with frequency compression

Abstract: The use of adaptive feedback cancellation to prevent howling requires a reference signal that is correlated with the Redback signal but is not correlated with the input signal. Such a signal is hard to obtain in hearing aids. In this paper, the use of frequency compression to decorrelate the output signal with the input signal for use as reference is presented. Performance evaluation results indicate that with the proper choice of system parameters, the use of this system can provide a significant increase in howling margin with minimal deterioration in output signal quality.

Measurement of long impulse response by using a time-stretched pulse

Abstract: The transfer function of an acoustic system, in general, often ex­ hibits a wide dynamic range and a very long impulse response. The time-stretched pulse (TSP) proposed by Aoshima (ATSP) has a small peak・facto호 and is accordingly suitable for the measuring impulse responses. The pulse is not so suitable, however, for the measurement of impulse responses over a wide frequency range. In this paper, we try to generalize and optimize this method (OATSP). This makes the method applicable for measuring of impulse responses longer than the length of the TSP. An analysis of error in such a case is also shown. Finally, we discuss how to implement this technique in specific measurement conditions.