Infants use spatial cues to hear voices in noise

In noisy environments, organisms differentiate sounds they want to detect from interfering noise to improve their perception of target sounds. This process is widely conserved across species, including birds, crocodiles, ferrets, and human adults. But how early in life does this ability emerge? In a new JNeurosci paper, Farhin Ahmed, Qianxun Zheng, and colleagues at the University of Washington explored whether infants also use this evolutionarily conserved mechanism for detecting sounds in noisy environments. 

The researchers recorded the brain activity of 53 infants and 20 adults as participants listened to speakers in different environments: One environment had just a speaker, another environment had surrounding noise coming from the same location as the speaker, and a third environment had noise coming from a different location than the speaker. 

Both infants and adults used sound location to track speakers, but their brain responses were different. In adults, there was widespread activation of the cortex whereas infants had more confined activity in the cortex. 

Summarizing the major takeaway from this study, says Ahmed, "Despite their immature brains, infants are still able to make use of spatial cues early in life to help them hear the relevant voice in a noisy environment."