Things change

I have been a clinical audiologist for about 35 years now and I am surprised when I look back just a few years and find that what I told my clients either was wrong, or merely simplistic, based on today’s knowledge. Front line clinicians always find this in their first couple of years of work- we are still trying to integrate some of the subtleties of our field and are still experimenting with “what works and what doesn’t”.

However after the first few years we all seem to settle into a routine that is informed by evidenced based knowledge of that time. Rarely however, does it take a 180 degree turn.

I was involved in the first studies of portable music, and back in the early 1980s we called the culprit, the “Walkman”. These had over the ear headphones and the maximum output (in a 2 cc coupler) was 112 dB SPL. With the advent of widespread use of real ear measurement in the mid-1980s, it became apparent that the maximum output could actually be much greater, especially with the newer insert earphones.

Puretone testing is sometimes like using a sledge hammer. Figure courtesy of www.dudeiwantthat.com

The media was quick to pick up on the story about the potential dangers of portable noise. But over the years, through the CD players of the 1990s, and the mp3 players in the past 15 years, we have failed to find a generation of people who have lost their hearing from recreational or portable noise. At most were 15-20 dB notches in the 4000-6000 Hz region.

Gradually the media lost interest in the “story” and clinically, my admonishments to my young music listeners became less and less stern. I might mention something about not using Q-tips, but frequently would just skip my blurb on the dangers of portable music.

Then 2006 came along and Doctors Sharon Kujawa and Charlie Liberman started publishing their research. Yes, pure tone thresholds appeared to return to normal but there could be permanent neurological damage that did not resolve. Of course not everyone is routinely tested with ABR so wave I delay could not be assessed and rarely is the AP/SP ratio determined. In 2006 and later in 2009 the studies showed that noise or music damage is not so obvious, and that gross measures of cochlear sensitivity such as pure tone threshold testing do not possess the necessary sensitivity.

The simplistic nature of a puretone audiogram. Courtesy of University College London Hospitals

The media have taken to calling this “hidden hearing loss” and while this is not all related to recreational noise sources, we are now starting to doubt statements such as “you have normal hearing” that are just based on pure tone threshold results.

For the last decade I am now back to admonishing my clients about the volume settings of their mp3 players.

Of course, our “admonishments” are much more sophisticated than they were in the 1980s. I would never say “don’t” but I would frequently talk about common sense moderation- if your favorite song comes along, turn up the volume, but then turn it down to a more reasonable level after.

We, as a clinical field, can always find creative approaches to conveying our warnings to our clients about the subtle effects of noise and music exposure; and these same approaches can help inform our clients about hidden hearing loss. Just because an audiogram is normal, hearing may not be normal.

About Marshall Chasin

Marshall Chasin, AuD, is a clinical and research audiologist who has a special interest in the prevention of hearing loss for musicians, as well as the treatment of those who have hearing loss. I have other special interests such as clarinet and karate, but those may come out in the blog over time.