Question
I can't figure out how to interpret my audiogram. I keep finding different standards for 'normal limits.' Some say it is 0-20 db, others 0-15 db. Some say it is 0-15 db for children and 0-25 db for adults. And yet others make it seem as though 0 db is the average threshold at all frequencies for 'normal hearing' young adults. I am very confused. What is the real standard for audiometry? If my threshold is at 15 db for some frequencies does that mean that although I am officially within 'normal limits' my hearing is still worse than the average young person?
Answer
You ask a good question, one that audiologists have been asking themselves for many years. The zero figure, as you imply, is simply an average of the thresholds obtained by "healthy young adults" under optimal conditions. The results themselves, however, fall in a "bell-shaped curve," in exactly the same way that other human dimensions do (think "average" height, weight, age for example).
The lower limits of what is considered normal gets influenced by how the information is going to be used. We know, for example, that children with even minimal hearing losses (e.g. within the "normal range" you outline) will, on the average, perform slightly poorer academically than other children, so we should watch them just a bit more closely. Young people should have better (lower) thresholds than an older person, although both can be perfectly normal for their age. For an adult, the best judgment I can offer is actual communication difficulty.
Dr. Mark Ross is a consultant to the Rehabilitation Engineering Research Center (RERC) on Hearing Enhancement, he is a Professor Emeritus of Audiology at the University of Connecticut, and has also served as the Vice President of the Hearing Loss Association of America (HLAA), formerly Self Help for the Hard of Hearing (SHHH). As a world renowned author and researcher in hearing rehabilitation and having worn hearing aids for almost 50 years.