In part 1 of this two part blog series, the characteristics of temporary hearing loss, also known as Temporary Threshold Shift (or TTS) were discussed. Using pure tone stimuli, TTS typically resolved in 16-18 hours – it was thought to be nothing more than a benign characteristic of noise or music exposure, with no predictive power. And while this was true of the research done prior to 2000- namely that cochlear sensitivity resolved using pure tones- research performed more recently examines the characteristics of the neural hookups between the inner ear and the brain. It is these neural connections and structures that suffer permanent degradation even after the pure tone thresholds due to noise or music exposure have resolved.
In view of the newer research on TTS over the last 10-15 years an app has been developed where TTS can be measured by anyone, using a Smartphone and any set of earphones (available from the Apple Store for the iphone and from the Google Store for Androids).
Start up screen of the Temporary Hearing Loss Test app
Using earphones a person can, within several seconds, measure their hearing threshold at 6000 Hz, and this number is saved. Without changing the volume setting on the Smartphone, the person goes to work in a factory, listens or plays music, or goes to a sporting event, and then immediately after the event, the hearing acuity is measured for a second time, and saved. This difference is a measure of TTS.
Because the app uses a “difference” between two measurements, no calibration is required. Measurements are valid as long as the Smartphone volume control has not been changed, and the “before” and “after” measurements were performed in similar environments.
Depending on the degree of TTS one of three screens will be shown- green colored for minimal TTS (<5 dB); orange colored for some degree of TTS (6-15 dB); and a red screen for TTS that is greater than 15 dB. Each screen has information about hearing loss prevention as well as a link to the FAQ page at the www.MusiciansClinics.com website. The data from the TTS measurement can be emailed along with the duration between the first and second parts of the test.
Using the Temporary Hearing Loss Test app individuals can now quickly assess whether the noise or music exposure resulted in a change in hearing acuity. And while repeated TTSs may only last 16-18 hours, as shown by Kujawa and her colleagues, long term neural damage may ensue. This app is not intended as a replacement for industrial assessment of the noise or of the dose, but does provide one more important piece of the hearing loss prevention puzzle. The Temporary Hearing Loss Test app simply addresses the important issue of whether there is TTS or not and how much, and this is evaluated on an individual basis.
Result screen (red) showing greater than 16 dB TTS along with hearing loss prevention information
While it is true that changes in puretones are a simplistic measure of the effects of loud noise or music, they can be used to assess TTS and can provide information to minimize long-term neural changes, and ultimately sensory changes in the hearing mechanism. These changes may result in tinnitus, hyperacusis, or eventual permanent hearing loss. More information can be found at www.MusiciansClinics.com.
NOTE: The editorial board at www.HearingHealthMatters.org have graciously allowed me to talk about the Temporary Hearing Loss Test app and I do have to state that this app was developed by myself at the Musicians’ Clinics of Canada. All proceeds go to supporting hearing health care activities through my Musicians’ Clinics. (Marshall Chasin, AuD).
