Does loud music destroy your hearing? Ben Duncan encounters the pain threshold and survives with all his senses intact. Well, most of them, anyway.

"I really must write... before we get some lunatic trying to subject some audience to sound pressure levels of 140dB in the belief that it is justified in the interests of the further development of the art form of music. Make no mistake about it — SPLs of that order are LETHAL..."
Ken Dibble, electro-acoustics consultant.

"When the board's input peaks at 2 volts, then you know you're getting 140dB or more up the mic; this happens quite regularly on close-miked percussion, horns and that sorta stuff."
Doug Hall, live-sound engineer for Iron Maiden.

In 1970, funk put a meat cleaver in my cranium.

Fourteen or more years ago when WEM and, later, Kelsey-Morris first unleashed high power PA systems, SPLs (Sound Pressure Levels) at gigs took something of a leap. (Sound Pressure is analogous to the perceived intensity — that is, loudness.)

Even using the relatively puny amps available at that time — circa 100 watts — the close-up SPL of a modest PA could suddenly top 115 or (shudder) 120dB. Later, players who couldn't afford bass bins or cope with the difficulties of transporting the bulk of those early PAs were treated to increasingly powerful amplifiers at descending prices.

Meanwhile, the power-handling capabilities of compact speakers have risen sharply. The result is that for some time now, PA systems capable of 120dB in the nearfield have been affordable to most working musicians. (Nearfield is the region close up to the speaker where the SPL is highest; for a big PA perhaps 20ft or more, while 6ft is typical for studio monitors.)

Thanks to the likes of Tannoy, the speakers in recording studios had always been well above average efficiency, though from a reactionary standpoint this advantage meant a tiny 10 watt valve amp could provide an'tar'lay ardi'qut levels, to quote a BBC engineer of the early 1960s. In other words, efficiency was seen not as a means to high SPLs, but a substitute for butch amplifiers — that is anything over 20 watts.

Nevertheless, macho power amps of 100 watts or more were smuggled into the country, and as the 1960s drew to a close recording engineers discovered the immediate benefits of high level monitoring in a room with well-behaved acoustics: rock music, defined as "something that occurs when sound exceeds 100dB", could slip into a new, more vital dimension when monitored at live, nearfield levels. High-level monitoring also revealed bass-end detail and upped bloodstream adrenalin levels, producing a chemical high if nothing else.

In the intervening 14 years, people in the business have observed that loud sound could be painful, but as the equipment improved, speakers in particular, the untoward effects of monitoring at high SPLs could be made to disappear.

Meanwhile, in the mid-1970s there was considerable hysteria about the effects of loud rock but, oddly, no histrionics have been directed towards errant orchestras, both classical and big-band, who've also played damned loud on occasions, and exceeded 120dB by puffing and slapping alone. Neglecting this discrimination, the sudden concern was a spin-off from the new awareness of widespread damage to the health of working people, exposed eight hours a day, 260 days a year to the pounding, relentless noise of industry.

What happens when people encounter a LOUD?

Domestic noise is different from industrial noise because it's sporadic and intermittent: do you sit in a room for eight hours at a time in the company of a vacuum cleaner plus spin drier plus Judas Priest album going perpetually full bore? Not surprisingly, then, researches cited industrial noise as a reason for (i) going deaf, (ii) developing high blood-pressure, (iii) developing ulcers, psycho-somatic illnesses, (iv) depression, paranoia, suicide, (v) running berserk around the factory or office floor, (vi) vomiting, and (vii) falling asleep. But this could have been arrived at by reasoning from first principles.

For example, when some archetypal paleolithic ancestors hear a twig snap, behold, they prick their ears. But should a sabre-tooth tiger roar gently in their ears (equals 120dB), lo, ye body delivereth a mighty shot of the magic juice, adrenalin. This enabled our ancestors to catapult 20 feet into brambles, leap free, tear up an unsuspecting conifer by its roots, strip off the branches, and hurl the caber at the tiger, which would promptly expire. Afterwards, any excess adrenalin could be put to good use, as the skin is torn off the poor beast. Put simply, all loud sound — over 80dB, say — is programmed to hype us up; it's a vestigial human survival mechanism. With this idea to hand, it's easy to suss why constant loud sound should be a source of severe stress to people in sheltered environs, because they're unable to release the "speediness" of the situation. Smashing up the Solid State Logic after eight hours of loud mixdown would be a good therapy, but it tends to push up the costs of making a record.

Heavy reactions to excessive LOUD

Anyhow, the point is that the disadvantages of loud, industrial noise aren't in dispute: the problem lay in do-good academics, who equated (rock) music with industrial noise. Duly, the GLC and other metropolitan authorities imposed outrageous sound level limits on rock performances similar to those applied to factories and the interior of tractor cabs, namely a 102dB maximum. Sadly, they neglected to notice the fact that no audience spends 2080 hours a year in the presence of loud music, that musical SPLs are variable (with up to 15dB between the peak and the average levels), and that punters' applause frequently exceeds the sound-level limit, making the gig illegal before a single note is played...

"Exceed that there mate," said the manager, sternly, "and t'music's off. When I point, turn down, see?" Wondering how the hell he was expected to keep an eye on the stern one, as he sauntered about the packed hall, the guitarist played nervously at first, but slowly gained courage, and picked up steam. Then it happened: the PA went abruptly dead. Kaput. Zero. The bass player recovered first, and went to kick the dodgy three-way adaptor, but before he reached it the PA plopped, and the sound came back. But too late: the audience's groove-thang had faded. Cut-out mechanisms (Orange Balls to you) are clearly incompatible with musical performance, an infringement on musical liberties, but perhaps there could be a more subtle means?

Relaxing in earshot of a LOUD

The cardinal mistake made by academics was to think negatively about the ironic fact that good music and tiresome industrial noise can be one and the same, when measured (and therefore defined) by their physical effects alone.

In other words, how does a decibel meter tell us that the 114dB it's registering is in fact a becalming, emotive or simply wistful tenor-sax line, and not the sonic devastation of the Vickers submarine yard? Or is it telling us that both are equal when it comes to assessing their effects on the human mind?

One reason why music could be less harmful than noise (defined as any random, meaningless sound) of equal level, is that the routine hearing damage brought about by industrial noise isn't by and large a result of exceeding purely physical limitations.

Rather, the deafness caused by constant exposure to sound in the 80 to 120dB region is a by-product of the stress induced by the unprincipled loudness. Essentially, "LOUD-induced stress" (to give it a pretentious title) includes a shutdown of the nerves in the ear. This is known as threshold shift, a temporary deafness. Most of you will have experienced it, and you've doubtless noticed that threshold shift doesn't cancel as soon as the LOUD comes to an end, but lingers till some time later.

For example, after an all night mixing session on certain XYZ monitors, an engineer reported being unable to hear the cars in the street the next morning. And regular LOUD may keep this threshold shift on the go for long enough to disable permanently some of the aural nerves; being persistently starved of blood, they shut down, decease, and leave you with impaired hearing.

But need loud music necessarily and inevitably bring about LOUD-induced stress? It needn't if it's "learnt" — in other words, once we develop a relationship with music we can, indeed must, lay aside the otherwise automatic symptoms of stress, and relax. To wit, someone familiar with live rock close up won't keel over and fall off stage when the pre-rehearsal "silence" is rudely cut-up by a 126dB booomf. "Yes, the kick drum is being tuned up, nice sound, that one; why are you running away...?"

What's being dug up here is that whereas loud noise is inevitably harmful, whenever sound is perceived as music it has the ability to shift our state of mind in the opposite direction. So despite the intensity of the sound (and remember, sound is the undifferentiated physical medium; noise and music are things we build with it), total relaxation will alter the consequences of high SPLs, effectively uprating the sound levels we can safely encounter up to the ultimate limit, which is purely a physical thing.

In other words, relaxation can allow us to cope with music, up to levels where the bones inside the ear literally drop apart; there's no intermediate hassle on account of stress reactions and the like.

Perhaps it's no coincidence that certain famous musicians — who can they be? — and producers whose hearing apparatus is known to be feeling slightly under the weather aren't exactly renowned for working under relaxed conditions. From another angle, Dr Spliff's research papers demonstrate that reggae musicians and their clients rarely suffer loud LOUD-induced stress, owing to beneficial medication.

Next month, Ben Duncan ties it all up, with more heretical questions: does sound have limits? Is it true that certain speakers cause deafness? If I can't hear much above 1kHz, surely I can compensate with EQ? And how does all this affect me?