Why Do We Need the Ling 6 sound Test?

Everyone who provides therapy for children with hearing loss knows about the Ling 6 Sound Test. Why do we do the test and what does it tell us?

What does a Child Hear?

For children to succeed with listening and spoken language they need to hear. To quote Dan Ling – “what they hear is what they say.” One of my first jobs was at the New York League for the Hard of Hearing (now the Center for Hearing and Communication) and Dorothy Noto Lewis, the director, would make us draw the child’s audiogram by listening to his speech – before we tested the child. It was a wonderful skill for me to develop and one I still use today, almost 50 years later. By knowing what a child hears and what she doesn’t hear, we know how to adjust technology settings to improve hearing, and we know how to plan remediation.

We expect technology to provide sufficient auditory information for children to use listening to learn. But how do we know that they have enough auditory access? NEVER ASSUME!!! Just because a child’s hearing aids are set according to the manufacturers specifications, does not mean that, for this particular child, they are hearing well enough. The same is true for cochlear implants.

I have talked about this in several previous blogs. Unless we test, we don’t know. Hopefully, the audiologist will have obtained aided thresholds in the test booth, and we will know that the child has sufficient auditory access across the frequency range. But, that only tells us that the child heard well enough on the day of the eval. It doesn’t assure that she is hearing well enough weeks later. And if the audiologist has not tested aided thresholds we have no idea at all that the child is hearing well enough. By testing the Ling sounds each day we can know that the child is hearing well on each and every day. And we can use the information obtained to help us understand how to proceed.

Detecting the 6 Sounds

The Ling 6 sound test is a quick and easy way to check on a child’s ability to detect the sounds, and as they get older, possibly to identify the 6 sounds. The sounds selected have energy from low through high frequencies – /m/, /ah/, /oo/, /ee/, /sh/, /s/. The parent or professional working with the child says the sounds in random order. It is important when presenting the sounds to present each sound with the same duration so as to give no clues (don’t make /sh/ longer than /oo/.

It is also important not to exaggerate the sounds. For example, in normal conversation /s/ is much softer than the vowels /ah/, and /oo/. We don’t want to exaggerate the loudness of /s/ but rather present it at the same loudness that it would normally be presented in general conversation so that we know how the child will hear in general conversation.

Young children will be asked just to indicate that they heard the sound by dropping a block in a bucket, raising a hand, or verbalizing that he heard it. This is a detection task. If a child indicates that she hears /m/, /ah/, /oo/, /ee/, /sh/, but does not hear /s/, it would indicate that she is not hearing high frequency information above 4000 Hz. If she hears /ee/, /sh/, /s/ but misses one or more of the low frequency sounds it would mean that she is not receiving enough low frequency information. Or possibly, the low frequencies are too loud and interfering with perception.

Older children will be asked to tell us what they hear – not just to detect the sound. We want the child to repeat back the sound they hear. By attending to the errors that they make we can know what is wrong with technology settings.

Using the Error Information

If a child cannot correctly hear /m/ we know that he is not hearing low frequency information and will likely have trouble hearing other low frequency sounds including vowels. We can expect that they will have difficult with rhythm and inflection and will likely develop nasal speech.

Vowels have energy in the frequency bands we call formants. The /oo/ vowel has energy in both formants in the low frequencies. The vowel /ee/ has low frequency information in the first formant but high frequency information in the 2^nd formant. So if a child is confusing /oo/ and /ee/ she may not be hearing the 2^nd formant. If she is confusing /oo/ and /ee/ and also missing /s/ they you definitely know she is missing high frequency information. You can expect abnormal voice quality. If /m/ and /oo/ are confused it indicates we need to work on building listening skills.

If a child is not detecting /aa/, (a middle frequency sound) then he will likely have problems hearing unstressed words and will have grammatical errors. If a child can hear /aa/ but not /m/or /oo than either the low frequency sounds are underamplified or the high frequency sounds are over-amplified.

The vowel /ee/ has both low and high frequency information so it provides a lot of information. If a child can detect /ee/ but cannot detect /m/ or /oo/ then it indicates that she cannot hear the low frequencies. If he detects /ee/ but not /sh/ then it indicates that he cannot hear the high frequency information.

High Frequency Sounds

High frequency sounds are relatively quiet sounds but also critical for speech and language information. Because they are soft and because children with hearing loss usually have poorer hearing in the high frequencies, these sounds are more easily missed. (Fortunately, cochlear implants have made hearing high frequencies less of a problem. The sound /sh/ is used to detect if mid-high frequency sounds are audible and /s/ is used to detect if very high frequency sounds are audible.

How to Use the 6 Sound test

Parents should use the 6 sound test EVERY day checking the technology worn in the right ear alone, the left ear alone, and with both ears together. They should note what the child can hear at 3 feet and at 10 feet. If technology is appropriate and appropriately set, we expect that the child will hear all the sounds at both distances. If the child makes errors, the error should be recorded and, if they persist, the child’s audiologist should be contacted. Listening and spoken language specialists and speech-language pathologists should do a listening check when the child comes for therapy and also record errors and report to the audiologist. Someone at school should check the equipment daily and if problems develop should refer back to whomever is responsible in the school.

We should also remember that children need to hear more than these 6 sounds. In fact, children need to hear every phoneme, so at some time, someone needs to check that the child hears everything. But every day, we need to check listening!

Thank you Dan Ling for this screening test and for all the other work you have done for children with hearing loss.