How You Hear — and How to Keep Hearing

Every other article in this track is about what sound does on its way to you. This one is about what happens when it arrives, because the last stage of every signal chain you will ever build is a pair of ears that cannot be replaced, repaired, or upgraded. Understanding how they work explains a surprising amount of otherwise mysterious studio behaviour — why a mix loses its bass when you turn it down, why the vocal disappears the moment the guitars come in — and it explains why the people who have been doing this for thirty years are so tediously insistent about earplugs.

The Part That Does Not Grow Back

Sound funnels down your ear canal and vibrates the eardrum. Three small bones pass that vibration to the cochlea, a fluid-filled spiral about the size of a pea. Inside it sits a membrane lined with thousands of tiny hair cells, and this is where sound stops being physics and becomes sensation: the membrane vibrates most strongly at different positions depending on frequency, the hair cells at those positions bend, and bending fires a nerve signal. High frequencies register near the entrance of the spiral, low frequencies deeper in.

The cochlea is organised by frequency, so damage is too — which is why hearing loss is never a simple, even fade. It takes the top off first.

And here is the part worth internalising: in humans, cochlear hair cells do not regenerate. Skin heals, bone knits, liver regrows. Hair cells are killed once and are gone for the rest of your life. There is no treatment that brings them back, and the loss accumulates silently across years of individually unremarkable nights.

Loud Is a Dose, Not a Moment

Damage is a function of level and time, in combination — the same way sun exposure is. A moment at a high level and a long stretch at a moderate one can do comparable harm.

The regulators broadly agree on where the line sits. In the UK, employers must act at a daily or weekly average of 80 dB(A), must provide hearing protection and protection zones at 85 dB(A), and there is a hard exposure limit of 87 dB(A). In North America, NIOSH recommends a limit of 85 dB(A) averaged across an eight-hour shift. Both land in the same place: around 85 dB(A) for a working day is where a career starts costing you something.

The part people underestimate is what happens above that line. NIOSH uses a 3 dB exchange rate, meaning the safe exposure time halves for every 3 dB of extra level. Three decibels does not sound like much. It is the difference between a full shift and half a shift.

Live music runs well past it. Measured properly — averaged across a whole night rather than caught at the loudest moment — studies of small live-music venues report roughly 86 to 102 dB(A), averaging in the mid-nineties, with concerts and clubs measuring much the same. That is ten to fifteen decibels above the point where an employer in a factory would be legally obliged to hand out protection, sustained for a couple of hours, several nights a week. At those levels the allowance that was measured in hours at 85 dB is measured in minutes.

A working musician is accumulating a serious occupational dose, in an industry that has historically treated protection as an admission that you are not really committed.

The Warning Signs You Already Ignore

That muffled, underwater feeling after a gig, where everything sounds like it is happening through a blanket, is called a temporary threshold shift. Your hearing genuinely is worse, and over the next several hours it mostly comes back. The word doing the damage in that sentence is mostly. A temporary shift is not a harmless quirk of loud nights; it is the sound of cells that have been stressed, and repeated often enough it stops being temporary.

Ringing after a show — tinnitus — is the same warning in a different form. It usually fades. It does not always. Tinnitus that stays is permanent, untreatable, and reported by musicians at far higher rates than the general population.

If you finish a night with either symptom, that night was too loud for how long you were in it.

Why Your Mix Loses Its Bass When You Turn It Down

Your ears are not equally sensitive to all frequencies, and — crucially — the shape of that sensitivity changes with level. At high volume, your hearing is reasonably even across the spectrum. As level drops, sensitivity to the low end falls away much faster than sensitivity to the midrange.

This is why a mix that sounded full and weighty at gig volume sounds thin and papery at conversation volume. The bass has not gone anywhere; you have simply stopped being able to hear it as well. It is also why everything sounds better loud, and why that is a trap: turn a mix up and it gains authority regardless of whether you actually improved it. Comparing two versions at different volumes is not comparing the versions at all — the louder one wins nearly every time.

The defence is to check your work at more than one level, and to make the important decisions quiet. A mix that holds together at low volume will hold together everywhere. The reverse is not true.

Masking: Why the Vocal Vanished

Play a loud sound and a quieter sound close to it in frequency at the same time, and the quieter one becomes inaudible — not buried, not subtle, genuinely not perceived. This is masking, and it is a property of the cochlea itself: the loud sound is exciting the same region of the membrane, and the quiet one cannot make itself distinguishable there.

Masking is not symmetrical. Low frequencies mask higher ones considerably more effectively than the other way around. This is why a bass guitar or a kick drum with too much energy can swallow a vocal sitting well above it, and why cutting the offender usually works better than boosting the victim. It is the mechanism underneath the whole practice of carving space with EQ: you are not making the vocal louder, you are moving something out of the way so the vocal can be perceived at all.

It is also the reason a stage that is too loud makes the singer inaudible even with plenty of level in the PA.

Protection That Does Not Ruin the Music

The standard objection to earplugs is that they wreck the sound, and with the cheap foam ones in the bar's first aid kit, that is completely true. Foam attenuates high frequencies far more than low ones. Everything goes dull and boxy, you can no longer judge tone, and you take them out.

Filtered musicians' earplugs solve exactly this problem. They are designed to attenuate roughly evenly across the spectrum, so the music gets quieter without changing character — the same mix, turned down. Off-the-shelf pairs cost about as much as a set of strings. Custom-moulded ones, fitted by an audiologist, cost more than that and are worth it if you play regularly; they usually take interchangeable filters so you can pick how much attenuation you want for a given room.

The ones that protect your hearing are the ones you can stand to leave in, which means the cheap foam pair you remove after two songs protects nothing at all.

What This Means for You

• Get filtered earplugs and keep them in your gig bag, not at home. Flat attenuation means the music survives; foam plugs do not and you will take them out.
• Treat loudness as a dose. Volume and duration multiply — stepping outside between sets genuinely reduces the total.
• Stand out of the direct firing line. A metre or two off-axis from a wedge or a PA stack costs you nothing and removes real level.
• Take ringing or muffled hearing after a show seriously. It is a warning, not a badge, and the recovery is never quite complete.
• Make mix decisions at low volume, and check at more than one. Loud always sounds better, which makes it useless for judging whether anything is better.
• Match levels before comparing two versions of anything. The louder one wins by default, whatever else is true about it.
• When something is masked, cut what is covering it rather than boosting it. Low frequencies mask high ones, so the fix is usually below the thing that disappeared.
• Get a baseline hearing test while your hearing is good. You cannot notice slow, symmetrical loss from the inside — only a measurement catches it early.