Effects of selected vocal disguises upon spectrographic speaker identification

This research was designed to investigate the effects of selected vocal disguises upon spectrographic speaker identification. The experiment consisted of open-trial, spectrogram-matching tasks with 15 ’’reference’’ and 15 ’’matching’’ speakers. The speakers produced two sentence sets in six different ways: (1) normal-speaking mode, (2) old-age disguise, (3) hoarse disguise, (4) hypernasal disguise, (5) slow-rate disguise, and (6) free disguise of his own choosing. The reference spectrograms were always undisguised speech samples; the matching spectrograms were either disguised or undisguised. Four trained spectrographic examiners completed the matching tasks. The results revealed that the examiners were able to match speakers with a moderate degree of accuracy (56.67%) when there was no attempt to vocally disguise either utterance. The inclusion of disguised speech samples in the matching tasks significantly interfered with speaker-identification performance. However, certain voice disguises were more effective than others. In addition, certain speakers were considerably more difficult to identify than others. In summary, this investigation did not substantiate prior claims that spectrographic speaker identification is unaffected by attempts at disguising one’s voice. Subject Classification: [43]70.65, [43]70.40.