Łukasz Pawelec of the Wrocław University of Environmental and Life Sciences analyzed whether voice features can reflect body composition - the proportion of body fat to fat-free mass such as muscle, bone, and body water.
The findings were published in the journal Scientific Reports.
Researchers have long asked how much a person’s appearance can be “heard” in their voice, including whether recordings might help investigators narrow down suspects in criminal cases.
“This is a fascinating area that we still know too little about,” Pawelec said.
In the study, body composition was measured using bioelectrical impedance, a painless method that sends a very low electrical current through the body.
Because fat conducts electricity much less effectively than well-hydrated tissues, the technique can estimate how much fat and lean mass a person has.
Pawelec said earlier work often relied on the Body Mass Index (BMI), which combines height and weight but does not distinguish between weight from muscle and weight from fat.
Pawelec’s team tested 204 adults, including 81 men, aged 18 to 72.
Participants completed a short survey, made voice recordings using sustained vowels and spoken sentences, underwent standard body measurements, and had body composition assessed by bioimpedance.
The analysis suggested that fat and lean mass influence male and female voices in different ways.
Among men, greater arm muscularity was linked to a lower-pitched voice, which Pawelec said could be connected to testosterone’s role in shaping the voice box and vocal tract.
By contrast, men with higher levels of body fat tended to show higher values of what specialists call the first formant.
Formants are acoustic properties that help shape vocal timbre - the quality or color of a voice.
Pawelec explained that lower formants, and a tighter clustering of them, are typically perceived as more masculine, described as deeper or darker.
A higher first formant in heavier men pointed to a brighter voice color, closer to what listeners often associate with female voices.
Pawelec noted that fat tissue is hormonally active and can influence sex-hormone balance, including through an enzyme called aromatase, which can help convert androgens such as testosterone into estrogens.
Because sex hormones influence the voice, he said, shifting balances could help explain some of the differences observed.
Among women, those with more abdominal fat tended to have louder voices than those with smaller waists, which Pawelec said may be linked to higher pressure below the vocal folds due to visceral fat in the abdomen.
Women with greater fat-free mass also tended to sustain a sound longer on a single breath, a measure known as maximum phonation time, which can reflect stronger respiratory muscles.
Pawelec cautioned that the links are still too weak for reliable identification. He said trained listeners could sometimes pick out people with higher fat levels from recordings, but their accuracy was only slightly better than chance.
For now, he said, voice-based clues might one day help investigators narrow a suspect pool rather than identify a person precisely.
(rt/gs)
Source: naukawpolsce.pl