Handbook of Language and Literacy Development - a Roadmap from 0 to 60 Months

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Hearing from Thirteen to Thirty-six Months - An Overviewclick to print Print
Research Review / Parent

Written by: Lori Leibold, University of North Carolina

Thirteen- to thirty-six month olds are busy exploring the world and discovering new information about the sounds they hear around them. Toddlers learn how to focus on the most important features of speech as they gain experience listening to different voices in many situations.

Assessing Toddlers' Hearing

Toddlers will continue to make head turns in response to sound until about thirty months of age. However, it becomes harder for audiologists and researchers to test children's hearing after their second birthday. Toddlers are clearly able to respond to sound. As any parent will tell you, toddlers get bored easily and they may simply decide they no longer want to participate. Audrey returned to the audiology clinic for a hearing check-up when she was just over two-years old. As a six-month-old, Audrey loved to turn her head to see the toys light up and dance around. Now as a toddler, Audrey has lost interest in the toy "rewards" and has refused to sit still and respond to the sounds.

Audiologists have had greater success using a procedure called Conditioned Play Audiometry (CPA) to examine hearing in toddlers and early preschoolers. In this procedure, children respond to sounds by playing a game. For example, Audrey learned to drop a block in a plastic bucket every time she heard a sound. She seemed to really enjoy her "important job" and listened carefully for the sounds in order to fill the bucket with blocks. CPA is used often for clinical hearing evaluations, but the procedure has been used less by researchers. As a result, there are many unanswered questions about auditory development during the toddler period.

Sound Localization

Toddlers listen to sounds that are produced from many different heights and distances. For example, Audrey's parents might talk to her while she crawls on the floor during play time or while she is in her high chair during meals. In order to learn about the rules of language, Audrey must be able to determine where all the different voices and sounds are coming from.

Researchers have shown that the ability to locate sounds in space depends on differences in the sound waves that reach both ears. Nico's father might talk to him while sitting nearest to his right ear. Nico hears his father's voice in both ears, but the sounds that enter his right ear are louder and arrive more quickly than the sounds that enter his left ear. These differences in sound between the two ears become larger between thirteen and thirty-six months as toddlers' heads grow. As a result, the ability to determine the location of sounding objects becomes more refined during this time.

Speech Production and Auditory Self-Monitoring

An explosion in world learning takes place during the toddler period. Parents are often amazed at how quickly their child is picking up new words. By twelve months, most babies have only one or a few "real" words. By twenty-four months, most toddlers have more than two hundred words. An important reason for this explosion in word learning is that children "overhear" their parents and caregivers talking around them. Nico's mother realized that she had to be very careful about what she said around him, even if it did not seem like he was listening. He seemed to pick up and repeat back everything he heard!

Toddlers also rely on their hearing to listen to their own voices as they are learning to talk. Children who are unable to monitor their own voice due to undiagnosed or untreated hearing loss often experience delayed or failed development of spoken language.

Degraded Listening Conditions - Reverberation and Background Noise

Toddlers have a harder time hearing and understanding speech in noisy backgrounds than adults or older children. The toddler period is critical for the development of speech and language. It is important that children are provided with the best environment for learning about sounds. Reducing the amount of background noise is a good first step.

Leibold, L. (2007). Parent/Caregiver Narrative: Auditory Development 13 - 36 Months. In L.M. Phillips (Ed.), Handbook of language and literacy development: A Roadmap from 0 - 60 Months. [online], pp. 1 - 8. London, ON: Canadian Language and Literacy Research Network. Available at: Handbook of language and literacy development