The University of Western Ontario has developed a new test to help evaluate hearing in children. It is a plurals test and it helps identify how well a child is hearing in the high frequencies.
Why are high frequencies important?
We need high frequencies to hear plurals, possessives, tense and contractions. If you don’t hear high frequencies you miss some important grammatical markers. When an adult female says /s/ it is at around 9000 Hz. What does this mean for a child learning language from his mom or from another female caregiver? What does it mean for learning in school from primarily female teachers? This is made more difficult because most hearing loss is worse in the high frequencies. Research has shown that both normal-hearing and hearing-impaired children learned new words faster with a wide bandwidth through 9000 Hz than with a bandwidth only through 4000 Hz.
High frequency phonemes
Phonemes that occur between 4000 and 8000 Hz include /f/, /th/ and /s/. In addition to being high frequency, they are also low level, only about 20 dBHL.
What do hearing aids do?
Hearing aids amplify sound to their limits, but most hearing aids do not have energy above 6000 Hz. Some hearing aids have extended bandwidth, but the frequency response of the receiver is still a limiting factor. This means that kids wearing them will miss a lot. But exactly how much? Frequency-lowering technology certainly helps address this problem, but again the question arises, how much?
The Plurals Test
The Plurals test is designed to evaluate precisely what a child is hearing in the high frequencies. It is exactly what its name suggests. It provides stimuli and the child has to determine if the word is singular or plural. Young kids can use pictures with two choices, and as they get older it becomes an open set test. This test should be used on a regular basis for kids with hearing loss (and adults too!). It will measure exactly how much a child is hearing and help determine how the technology needs to be adjusted to ensure that the child hears the high frequencies. Fortunately, Phonak is distributing the test free of charge, so it should be easy for everyone to use it.