Improving the speech intelligibility of forensic audio recordings through adaptive filtering with non‐synchronous interference signals.

Forensic audio recordings are frequently made in uncontrollable acoustic environments where background sound emanating from television, radio, and video or music playback may interfere with the intelligibility of the intended “target” speech on a recording. In such cases, adaptive filtering techniques have proven highly effective in eliminating the interfering sound sources and improving intelligibility, provided that the interfering reference signal was acquired simultaneously with the target speech. However, in cases where interfering signals are acquired through a post hoc retrieval of broadcast, music, or video recordings, non‐linear time base differences between the original and the secondarily acquired reference may significantly lessen the effectiveness of conventional adaptive filtering techniques in improving speech intelligibility. The current paper describes the results in applying a commercially available, adaptive filtering tool as well as a newly developed tool, drift‐compensated adaptive fi...