Under particular circumstances, hearing aid use can be associated with Temporary Threshold Shift (TTS) and/or Permanent Threshold Shift (PTS). These terms are used to describe the worsening of hearing after the ear has been exposed to loud noise.
TTS is a temporary change in hearing. Many people, including people with normal hearing, experience TTS after exposure to loud sounds. If TTS occurs over a long period of time it can lead to a permanent loss of hearing (PTS).
Hearing aids fitted to people with severe-to-profound hearing impairment may be very powerful and deliver very loud sounds to the ear and therefore cause TTS.
The NAL-NL1 prescription is one of the safest, most effective prescription methods of hearing aid amplification available. Hearing aids now use compression circuits that increase the protection available for high level inputs. Research has shown that amplification won’t cause deterioration in hearing in the vast majority of clients. However, for a very small number of clients (less than 0.05%) even the NAL-NL1 prescription and typical input levels may still result in temporary worsening of hearing levels.
If the hearing aid is regularly used at volume settings higher than recommended, this increases the likelihood of temporary threshold shift occurring. This temporary worsening of hearing recovers almost completely overnight. Provided this type of change is recognised early and appropriate action is taken, no permanent change in hearing levels need result.
Children who often use their aids during very noisy activities are at increased risk of a noise-induced change in their hearing. They should use ear protection during woodwork and metal-work activities in the same way as other students.
Australian Hearing will check and compare your child’s hearing test results over time to see if any changes are occurring. If hearing levels are getting worse, your child’s hearing will be checked to see if the hearing aids are producing the change, and if so, its response will be altered to prevent any permanent damage to hearing. It may also be necessary to refer on to an ENT specialist since the deterioration of hearing can be due to a medical condition which may be treatable.
Disclaimer: The information contained on this website is not intended as a substitute for independent professional advice.
14-Nov-2015 7:53 PM (AEST)