Washington - All around the world, parents talk differently to babies than they do to adults.
With their young children, parents switch into a mode of communication known to linguists as "motherese" or infant-directed speech, and known more commonly as baby talk, a form of speech featuring long pauses and a roller coaster of pitch changes.
For example, picture the upward swing in pitch that our voices take toward the end of a question ("Do you want to go to the park today?"): It's much more dramatic when we address young children than adults.
While parents may feel a bit silly using baby talk, they shouldn't: Babies not only prefer listening to these exaggerated contours, but they also learn new words more easily from them. By highlighting the structure of speech, such as the differences between the vowels "a" and "o," motherese helps babies translate a torrent of sound into meaningful units of language.
Although scientists know a lot about the changes in rhythm and pitch in infant-directed speech, we know much less about the role of timbre, or tone color, which includes the breathiness, roughness or nasality in a voice.
The timbre of an instrument (whether buzzy, warm or twangy) clearly affects how we experience music, but its role in language is less obvious. When my colleagues and I looked into the tone color of baby talk, we made some surprising discoveries.
Mothers change their overall timbre when speaking to babies, almost as if they're morphing their voice into a different instrument to address these unique little listeners.
Timbre is a complex acoustic feature that helps us distinguish the unique flavors of sounds around us. For example, Barry White's silky-smooth voice sounds different from Leonard Cohen's gravelly one or comedian Gilbert Gottfried's nasally one even if they're all singing the same note.
Contorting the shape of your vocal tract (which goes from your vocal cords all the way up to your lips) results in different resonances, allowing celebrity impersonators and voice-over artists to change their overall timbre.