An optimum computer-generated pulse signal suitable for the measurement of very long impulse responses

Abstract

Transfer functions of acoustic systems often exhibit wide dynamic ranges and very long impulse responses. A ‘‘time-stretched’’ pulse as proposed by Aoshima (ATSP), though originally given in a very specific form seems to be one of the most promising signals to measure transfer functions with characteristics of acoustic system mentioned as above. In this paper, this pulse (ATSP) is first generalized and then optimized for the measurement of long impulse responses. This optimized ATSP (OATSP) has an almost ideal characteristic to measure impulse responses shorter than its specific length N. Moreover, it is newly shown in this paper that OATSP has also a good characteristic to measure impulse responses longer than N. Discussion is presented on how to design OATSP suitable for a specific situation of measurement by analyzing errors, when the pulse is used to measure impulse responses longer than N.

A two-channel impulse response measurement system based on a DSP starter kit

“…The available conditions are the number of points of a TSP, a parameter that determines the length of a TSP, and the number of repetitions. Note that although a longer TSP has larger power and results in a higher SN ratio, it also increases an error caused by linear convolution with its inverse TSP [1]. Since the error tolerance may differ depending on the requirements of the user, the system allows the user to determine this parameter.…”

“…A method using a time stretched pulse (TSP) to measure the transfer function of an acoustic system with a high signal-to-noise (SN) ratio has been proposed [1]. A typical application of this method is to measure the head-related transfer function (HRTF), which describes the spectral filtering that occurs between a sound source and the listener's ear, when employing the binaural technique [2].…”

Multiple-nulls-steering beamformer based on both talker and noise direction-of-arrival estimation

“…Also, most experimental conditions are the same as those in the computer simulation. However, room impulse response was measured by the time stretched pulse (TSP) method [13]. Room reverberation was T ½60 ¼ 0:7 s, and ambient noise level was L A ¼ 28 dB.…”

Simple prediction method for sound propagation behind edge-modified barriers

“…The channel array consists of six aluminum Ushaped channels. The impulse response from the source to the receiver is measured by the swept-sine signal method [11]. In the measured impulse response, the direct diffraction from the edge is followed by undesirable reflections from the floor and other inner surfaces of the test room.…”