What are the acoustic qualities that make a voice unique? What makes a voice recognizable over the telephone?
These are just two of the questions Patricia Keating and Jody Kreiman, linguistics researchers at UCLA, are trying to answer in their most recent study.
Voice is not a constant. A person’s voice can change depending on mood and emotional state, as well as other physiological factors. Despite this variability, the human brain can recognize individual voices.
Research suggests human listeners -- and their brains -- organize voice variability into a prototype for each speaker, a sort of average representation of what each person sounds like. This powerful organizational ability allows listeners to distinguish and recognize single syllables from different speakers.
Yet, scientists have struggled to establish exactly which acoustic qualities are most important in differentiating one prototype from another.
As part of their search, Keating and Kreiman recorded the voices of 50 women, all native English speakers, reading five sentences twice on three different days. They analyzed each speaker’s voice, measuring fundamental frequency, harmonic frequencies and noise levels. Each speaker’s collection of sentences provided a quantitative average and range for the three acoustic factors.
The collection of data produced a sort of acoustic profile for each speaker’s voice.