Listeners can not only distinguish the age and gender but also can accurately determine the relative heights of speakers just by listening to them talk, finds a new study.
The key clue may be contained in a particular type of sound produced in the lower airways of the lungs, known as a subglottal resonance.
"The best way to think about subglottal resonances is to imagine blowing into a glass bottle partially full with liquid: the less liquid in the bottle, the lower the sound," John Morton, a psychologist at Washington University in St. Louis explained.
Despite the masking of the subglottal resonance by other voice sounds, Morton and his colleagues wondered if the key information it contained could still be heard by listeners.
Through two sets of experiments, he and his colleagues put the theory to the test. In the first, pairs of same-sexed "talkers" of different heights were recorded as they read identical sentences.
Later, the recordings were played to listeners who guessed which of the two speakers was the tallest. In the second experiment, listeners ranked five talkers (again of the same gender) from tallest to shortest, after hearing them read.
The researchers found that participants were able to accurately discriminate the taller speaker 62.17 percent of the time, which is significantly more often than they would by chance alone. "Both males and females were equally able to discriminate and rank the heights of talkers" of both genders, Morton said.
The study was presented at the 166th meeting of the Acoustical Society of America in San Francisco, Calif.