One of the key questions in the examination of audiotapes is whether they are authentic and whether they have maintained their integrity from time of recording to introduction into evidence. The typical surveillance recording is usually poor and may be degraded by radio frequency interference, hum, wind noise, or ambient background noise. Audiotape authentication involves the components of critical listening, magnetic development, waveform analysis, tape enhancement, spectrum analysis, phase continuity, speed fluctuation/flutter, and voice identification. As with audiotapes, videotape analysis is usually concerned with the authenticity and integrity of the signal. Examination is usually visual and aural and is concerned with such questions as whether the tape is a copy, a compilation, or edited. Equipment used in such analyses include a waveform monitor, a vector scope, and a cross-pulse monitor. Based on the results of subjective and objective, machine-based measurements, a conclusion of the authenticity of a tape usually can be made. 10 references.