Research

We use behavioral (psychoacoustic) tests to measure auditory perception in infants, toddlers, children and adults with normal hearing as well as those who use cochlear implants. Performance on these tests is compared to performance on auditory speech and language measures. We are interested in how spoken language development over time is related to auditory perception. The long term goal is to develop a set of clinically valid auditory tests to measure how well a cochlear implant works for an individual infant. This will enable audiologists and speech pathologists to intervene early for children who are not receiving optimal benefit from their cochlear implant.

Background

Auditory Skill Development

When babies are born with typical hearing, they are exposed to a variety of sounds. Over time, their brain takes these sounds and puts them together into meaningful sounds, what becomes language!

We can break up the auditory skills required to build language into 4 parts:

  1. Detection
  2. Discrimination
  3. Identification
  4. Comprehension
  1. To develop appropriate language, you first need to have access and be able to accurately hear all the sounds. We can think of this auditory process as awareness or detection.
  2. Now we hear sound is happening, but what if it all sounded the same? The next auditory process is discrimination, or the ability to hear the difference between sounds. Now we know there are many different sounds.
  3. The next step is auditory identification. This is where sounds become meaningful and we start labeling and recognizing sounds. If you say “cow” your child can point to the picture of a cow.
  4. Finally, there is auditory comprehension. This is when you take those meaningful sounds and words and understand the way we communicate with one another. Examples of auditory comprehension are following directions and turn-taking in conversation.

Though language takes years to develop, some of the listening skills required for language development occur in a newborn baby. For example, a baby born with typical hearing is born with sound awareness and access to sounds. A baby with a cochlear implant may or may not have had sound awareness prior to getting their implant. Some other important listening skills, such as discrimination, can develop within the first 6 months of hearing!

Auditory Development with a Cochlear Implant

For infants, CI mapping (programming) works by providing hearing access to all of the speech sounds. Audiologists look at the infant’s detection, or ability to hear soft sounds, at different pitches. For older kids and adults, CI mapping also includes discrimination and recognition of sounds. For example, can you hear the difference between “Pan” and “Pam”,
and can you repeat back “Ball”. These are called speech perception tests. In combination, a listener’s ability to both detect the sounds and recognize different sounds is important for developing strong oral language skills.

We cannot perform speech perception tests on infants and young children because they need language to participate. At 2-3 years of age, children may start completing a limited number of speech tests using pictures. As they get older, children may complete other speech tests by repeating back words. This leaves a gap of time between measuring an
infant’s auditory detection and auditory identification with their cochlear implant. In our lab, we want to know if we can measure an infant’s ability to perceive and discriminate sounds to better predict how well they will understand speech as they age.

Our Studies

In our current research, we are primarily focusing on the level of auditory discrimination. To understand speech, listeners must be able to discriminate sounds based on patterns of acoustic intensity variation, or modulation, across frequency or time. You must have auditory access (hear the sounds) and also auditory processing capabilities. If you hear three sounds–two are the same and one is different–can you tell me which sound was different? Over time, the “different” sound begins to sound more similar to the other sounds to the point when you no longer hear the difference.

We measure these auditory processing abilities in different groups across the lifespan: infants, school-age kids, and adults. Specifically, we evaluate a listener’s ability to discriminate sounds based on timing or pitch differences. We may also measure their ability to understand speech in quiet and with background noise. We look at the development of
these listening skills as well as the difference between listening with or without a CI.

Some of our Questions

  • How a listener’s ability to discriminate sounds based on timing or pitch differences relates to their ability to understand speech
  • Whether receiving a cochlear implant early in life affects how hearing abilities develop
  • How infants’ early hearing abilities with a CI predict later speech understanding

More Info on Cochlear Implants