I thought I would write this blog article to clear up some potential for confusion regarding audiometric testing results. As many of you know we provide audiometric screening tests, within the report you receive following the assessment. There is both a ‘percentage hearing loss’ calculation as well as a ‘degree of hearing loss’. The potential for confusion arises as these are two different values and are not in any way correlated with each other.
The percentage loss calculation is based on the National Acoustic Laboratories (NAL) report No 118 that was published in January 1988. This calculation factors in the whole range of hearing between 500Hz and 8000Hz and gives a percentage loss score for both the left, right and binaural. This is the calculation that is used by insurance agencies for determining compensation for hearing loss.
The degree of hearing loss is reported as either Normal, Mild, Moderate, Moderate to Severe, Severe, or Profound hearing loss. This determination is made by taking an average of the person’s hearing threshold levels at 500Hz, 1000Hz, 2000Hz and 3000Hz ranges. The reason these ranges are used is they are the typical ranges of human voices.
The percentage loss calculation is good to give a baseline as to someone’s overall hearing and for use in compensation, while the degree of hearing loss is used to determine if someone needs further examination by a hearing specialist. We refer people for further examination if the average hearing threshold level in their better ear is 40dB or higher.
If you have any further queries to this or would like to discuss in more detail, please feel free to get in contact.