Learning to talk changes how we hear speech: study

Canadian researchers using an unusual robotic device have determined that learning to talk changes the way people hear speech.
The robotic device used in the language experiment to isolate the movements involved in talking. ((McGill University))
Canadian researchers using a robotic device have determined that learning to talk changes the way people hear speech.

Sazzad Nasir and David Ostry of the department of psychology at McGill University in Montreal used a device that puts pressure on a person's jaw to try to isolate the movements of talking from the sounds of language itself.

The device pushed on the jaw causing it to protrude but didn't affect the speech sounds the subject were making.

In an experiment, described this week in the Proceedings of the National Academy of Sciences, 44 volunteers were given auditory tests and asked to identify lists of spoken words that sounded similar, such as "head" and "had."

The robotic device was then placed on the subject's jaw, and they were asked to repeat a set of randomly selected words aloud, such as "had," "bad," "mad," and "sad."

Many of the volunteers were able to overcome the load placed on their jaws by the device and pronounce the words with normal jaw movements.

The volunteers then took the test again. The researchers found that the people who underwent the training with the robotic device got different results in their auditory tests, a change that wasn't seen in a control group that didn't use the device.

However, the change in perception of the spoken word was only seen in volunteers who learned how to overcome the pressure the device was putting on their jaws, the researchers said.

"Our work proves that people hear the speech sounds differently after motor learning," said Ostry, in a statement. "This confirms speech learning affects not only the motor system but actually changes sensory function.

"Learning to talk makes it easier to understand the speech of others."