Investigation of the effect of a time window on the accuracy of an estimated impulse response

The present paper describes the effect of a time window on the accuracy of impulse response estimation using the cross-spectral technique. Time windows used in this technique have been investigated both for time discrimination and for frequency characteristics (i.e., band width of the main lobe and magnitude of the side lobes). However, such investigations have not fully accounted for why the accuracy of estimated impulse responses is decreased. This paper describes those reasons, and recommends what type of time window should be used to accurately estimate the impulse response for two typical cases: one, where the transfer function is expressed as a simple time delay; and the other, where the impulse response is represented by an exponentially decaying white noise-the most simple model of an impulse response of a room.