What’s your Dynamic Range?
Or perhaps the question should be – what is dynamic range and how does it affect your hearing?
Dynamic range is, to put it simply, your usable range of hearing. It is the amount of decibels (dB) from the softest sound you can hear (your hearing threshold) to where sound is painfully loud (uncomfortable loudness level).
For people with hearing within the normal range, their dynamic range is generally around 100dB of usable hearing.
For example, if your threshold of hearing is 10dB and your uncomfortable loudness level is 105dB, your dynamic range is 95dB of useable hearing.
This sounds great, however if your hearing deteriorates, often so does your dynamic range. If your threshold of hearing is 45dB and your uncomfortable level is still at 105dB, your dynamic range is now 60dB of useable hearing.
If your dynamic range is reduced, you may also have what is known as recruitment. Defined as the ‘abnormal growth in the loudness sensation’, recruitment is when your ear can’t discern loudness in a linear sense. This means sounds go from very soft to uncomfortably loud in an abnormal manner, making it difficult to tolerate louder sounds. About 50% of people with hearing loss will also experience recruitment. It is generally associated with people who have their hearing affected by excessive noise.
Hearing aids and dynamic range
If you have a hearing loss, your dynamic range will undoubtably be reduced and you may experience recruitment. Both of these issues will affect your hearing aid fitting and the skill of your clinician to ensure your hearing aid prescription fits your dynamic range. Your hearing aid needs to be set comfortably within your dynamic range, so that loud sounds are not uncomfortable or painful for you, with your hearing aids on.
In your initial hearing test, your clinician may check your uncomfortable loudness level (UCL) for each frequency and use this information when selecting and prescribing hearing aids.
When you get fitted with hearing aids, your clinician will generally perform some tests to check the loudness comfort of your devices. This may be carried out through the computer programming and also so through some basic testing with ‘real life’ loud sounds. This can involve loud hand clapping, rattling of coins in a jar or banging keys on a desk. Clinicians will employ various methods of creating loud sounds to see how you react to them.
They will ask you if the sounds are ‘painfully loud’ or if you can tolerate the noise. This is checking how you cope when the maximum power output (MPO) is reached with the hearing aids that have been selected. If the sounds are painful or you are unable to tolerate them, the clinician will adjust the MPO to fit within your dynamic range.
In some cases, the testing of the MPO might not be accurate and you discover this once you are out wearing your hearing aids if there are many sounds that are causing you discomfort.
If this happens, contact your clinician to get your hearing aids adjusted. The sounds you hear need to be comfortable, within your dynamic range of hearing. Yes, there will be loud sounds, but if many sounds are making you flinch or feel uncomfortable, your hearing aids need further adjustment.