In fairness most audiologists will stick to the British Society of Audiology (BSA) guidelines for Pure Tone Audiometry (PTA), however fewer and fewer are conducting the ULL test. The reason for this? The ULL test was actually a standard part of the PTA procedure until 2011, when the PTA procedure was re-written by the BSA and the ULL section was removed and made into its own procedure.
The ULL test is important for two reasons: the short version is 1. your safety; and 2 your clarity and comfort. Want more detail? Read on….
The only thing worse than hearing aids that are too quiet, are hearing aids that are too loud. While you want to ensure that you can hear your family, friends, TV and so on, clearly, the last thing you need is to be on a busy street when a truck roars by, causing you to clutch at your ears because the sound is excruciatingly loud.
By testing to establish what your Uncomfortable Loudness Levels are, the Maximum Power Output (MPO) of your hearing aids can be set just below this point, so that loud sounds will still be heard as loud sounds but will not go beyond that level that is uncomfortable for you.
I’m going to get quite technical here, however if you’ve made it this far then you probably possess the same geek gene as me, so bear with me…
The Decibel scale is a logarithmic scale rather than an arithmetic scale, therefore accurate compression ratios are critical in determining the correct levels of amplification at different frequencies in order to maximise what is left of the residual dynamic range of hearing. By this I mean that as the level of external input volume increases, the rate at which the hearing aids amplify must necessarily decrease in order to maintain comfort and clarity.
If ULL testing is not conducted and the results not recorded in the programming of the hearing aids then default ratios are assumed, leading either to situations of over-amplification, causing distortion; or under-amplification, resulting in insufficient output i.e. not enough sound.
What this means for you would be the same – lack of clarity and/or comfort when you need it most. Since my job is to maximise these for you, I will always conduct a ULL test.