A new study suggests that mothers shift the timbre of their voice in a specific way when they talk to their infants. The results of the study were found to hold true irrespective of a mother's native language.
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Elise Piazza from Princeton University stated that the timbre, which is the unique quality of a sound, is used by everyone all the time to differentiate animals, people, and instruments.
Researchers had concentrated on the vocal cues that parents alter when they talk to their baby without even realizing they're doing it. The researchers taped 12 English-speaking mothers during the time they read or played with their 7- to 12-month-old babies. They also taped those mothers while they conversed with another adult.
After evaluating each mother's distinctive vocal fingerprint utilizing a brief measure of pitch, researchers identified that a computer could differentiate infant talk from normal speech just on the basis of one second of speech data. This is performed using a machine learning approach. The researchers confirmed that those variations couldn’t be justified by background noise or pitch.
The next concern was to find whether those variations would hold true in mothers speaking other languages. The researchers enrolled another group of 12 mothers who spoke nine distinct languages, including Cantonese, Mandarin, Hebrew, French, German, Hungarian, Polish, Russian, and Spanish.
Surprisingly, researchers determined that the shift in timbre noticed in English-speaking mothers was highly stable among those languages as well.
Pizza affirmed: "The machine learning algorithm, when trained on English data alone, could immediately distinguish adult-directed from infant-directed speech in a test set of non-English recordings and vice versa when trained on non-English data, showing strong generalizability of this effect across languages."
Therefore, differences in timbre between infant-directed and adult-directed speech may signify a universal communication form, which mothers indirectly utilize to engage their infants and assist their language learning, Pizza added.
The researchers reveal that the next step is to discover how the shift in timbre aids babies in learning. They doubt that the distinct timbre fingerprint could aid infants to learn to distinguish and target their attention towards their mother's speech from the time they are born.
Also, the researchers say that the results will probably apply to fathers too.