Acoustic reflections in impulse responses can be eliminated by truncation to short observation times that exclude the reflections. However, truncating the response tail distorts the corresponding low-frequency transfer function. When reflections in ”semianechoic” data originate from moderate-sized objects, e.g., equipment in anechoic chambers, their composition is mostly high frequencies. Consequently, truncation must only be performed in the mid to high frequencies where the information is contained in a brief time interval; the impulse response tail is anechoic for the low frequencies and can be retained. The authors present a frequency-dependent truncation approach that exploits this property by adapting the truncation length in each band. This avoids low-frequency errors while disturbing reflections are windowed out. Among several tested formulations, a novel Short Time Fourier Transform-based formulation generated the least artifacts while the anechoic impulse response was well preserved in both simulated and measured semianechoic data.
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