New research from Princeton University in New Jersey found something else special about how adults — in this case mothers — speak to their very young children. “ We found for the first time that mothers shift their timbre ,” said Elise Piazza, a postdoctoral researcher at Princeton University. Piazza added ,“ Timbre is best explained as the unique quality of a sound. Barry _ White ’ s _ silky _ voice _ sounds _ different _ from _ Tom _ Waits ’ _ poor _ one — even _ if _ they ’ re _ singing _ the _ same _ note. ” Using special equipment, Piazza and other Princeton researchers found that mothers shared similar changes in timbre when speaking to babies. The researchers tried to record the sounds mothers used with their babies at home. “ We chose to record mothers playing with and reading to their own babies just like they would at home ,” Piazza said. She wanted the discussions to be as natural as possible. The research offers new ways to show differences between how adults speak to babies, compared to fellow adults. The research was not limited just to English speakers. Researchers listened to discussions in seven other languages: Mandarin, Polish, Russian, Spanish, Cantonese, German, and French. Piazza said the research provides more information besides what is mentioned above. For example, she said, it could include how people change their timbre when speaking to friends or managers at work; how candidates speak to voters; and how people speak to their boyfriends, girlfriends or spouses( 配偶 ) . The Princeton research follows earlier research on baby talk. In 2014, researchers from the University of Washington and University of Connecticut looked at thousands of verbal discussions between parents and babies. They compared regular speaking voices and baby talk. Patricia K. Kuhl, a co ­ director of the University of Washington, said researchers found that use of baby talk led to better early language development.