You know that ringing in your ears that happens after listening to very loud music? Everything sounds like you are under water? You really shouldn’t be listening at such levels…
That ringing in your ears afterward is warning you that you face impending hearing damage if you keep it up. That underwater sound is the result of a temporary (!?!) threshold elevation in your hearing at higher frequencies. Sound exposure is cumulative, so a brief exposure to overly loud sounds won’t be too much to worry about. But don’t persist.
I have measured the half-life of that threshold elevation, and find it to be approximately 20 minutes. So it takes about an hour to restore your hearing to within about 10% of what it normally is.
That is interesting, from a tangential fact, that the EBU mandates that broadcasters measure their average integrated loudness levels each hour, to produce a compliance log. Whether they knew about the half-life or not, they picked a duration that would allow each 1-hour block to be relatively unaffected by preceding blocks of time.
That would also imply that it makes little sense for loudness meters to report over durations much longer than an hour. Nothing that happened more than an hour ago can affect your present hearing by very much.
I have been quite interested to watch most of my clients actually choosing to listen at much lower levels after I have calibrated their audio systems for them at -23 LUFS / 77 dBSPL. I use that calibration reference level in the lab here, but it does seem loud – comfortably loud. I wouldn’t want to listen much louder for any extended period. Most people choose more conservative listening levels for themselves.
As a side note, is there any connection between that ringing sound and tinnitus? Perhaps so, but maybe not.
It seems true that damaged hearing is often accompanied by tinnitus. I have it ringing off the hook. And it can drive some people crazy. But I only notice it if I choose to listen for it. By distracting my hearing with music, I don’t notice it at all during playback.
But I remember as a young 20-something, I could walk into jewelry stores and hear their ultrasound burglar detectors (about 19 kHz), and old TV sets with their 15 kHz flyback transformers would drive me nuts. I don’t think my tinnitus is that high up. In fact I’m sure of it. My tinnitus is down around 6-7 kHz.
So maybe that’s the frequency range where I listened to damaging levels of sound? I don’t know. I used to ride motorcycles a lot. And that is impulsive noise – very broadband in spectral content. And I listened to a lot of loud rock music too, but that doesn’t especially peak in the 6-7 kHz range. So who knows?
My left ear notch frequency is down around 1.3 kHz. My left ear hyper-recruitment is around 1.8 kHz, just above the notch. But my general decruitment seems to set in over a fuzzy range up around 6 kHz and higher. Perhaps the tinnitus frequency tells us something about where to find decruitment hearing?
- DM
