In fact the myriad of sounds bombarding a babes' ears make it difficult to distinguish a single sound from all the surrounding noise, says a University of Washington scientist. This could explain why getting a youngsters attention while there are other noises such as the TV or radio, is so difficult. Babies are generalists and hear all frequencies simultaneously so they can respond to unexpected sounds, says Lynne Werner, a UW professor of speech and hearing science. In real life we are confronted with a variety of sounds. Somehow the adult brain takes all sounds we hear and separates them into where they are coming from and then focuses on the one we want to hear.
Adults usually hear in a narrow band of sound, while babies seem to use a different approach.
They don't have the selective attention of adults and they don't pay attention all of the time. Instead they always seem to be listening broadband or to all frequencies simultaneously. Speak up Researchers have known for some time that babies are born with functioning hearing and that sensitivity to sound improves dramatically during infancy. Improvements continue through to about age 10, when the average child's hearing is comparable to an adult's. To further understand how babies hear, Werner tested 73 infants ages seven to nine months and 40 adults 18 to 30 years old.