Using the reassigned spectrogram to obtain a voiceprint

While established methods for imaging the time-frequency content of speech—such as the spectrogram—have frequently been christened ‘‘voiceprinting,’’ it is well-known that it and other currently popular imaging techniques cannot identify an individual’s voice to more than a suggestive extent. The reassigned spectrogram (also known by other names) is a relatively little-known method [S. A. Fulop and K. Fitz, ‘‘Algorithms for computing the time-corrected instantaneous frequency (reassigned) spectrogram, with applications,’’ J. Acoust. Soc. Am. 119, 360–377 (2006)] for imaging the time-frequency spectral information contained in a signal, which is able to show the instantaneous frequencies of signal components as well as the occurrence of impulses with dramatically increased precision compared to the spectrogram (magnitude of the short-time Fourier transform) or any other energy density time-frequency representation. It is shown here that it is possible to obtain a reassigned spectrogram image from a person’s voice that appears to be sufficiently individuating and consistent so as to serve as a true voiceprint identifying that person and excluding all other persons to a high degree of confidence. This is achieved by focusing on just a few phonatory pulsations, thereby revealing the vocal-fold vibrational signature unique to each person.