Mother's Voice and Monkey Call Sound the Same to Baby.

Infants are acute listener - they perk up more to people talking than to white noise. And we've all heard that infants recognize and react to the mother's voice.

But research by Athena Vouloumanos, a psychologist at McGill University, sheds a surprising result:

The McGill research group measured a newborn's level of interest in sounds by giving them sterilized pacifiers that measured the frequency and intensity of the baby's sucking.

"There are all kinds of suckers: soft suckers, hard, rapid and slow. When they suck hard, they get to hear a sound, and when they're aroused they suck hard," Vouloumanos said.

The team tested babies that were 10 to 96 hours old by playing recorded sounds of human speech and alternating with recordings of monkey calls. The researchers chose to use rhesus monkey calls because they have a similar vocal tract to humans.

The babies sucked the same for both sounds.

http://www.livescience.com/humanbiology/060217_baby_listen.html