Noises Offby Mary Ann Coggins Kaza and Jonathan Dubay
When it comes to sound, one can have too much of a good thing. This is true in any environment, including the concert hall. For the concertgoer, the difference in sound levels between unamplified classical concerts and amplified Pops concerts is certainly noticeable—and perhaps a matter of preference. For the musicians, the loudness of concerts and rehearsals can approach critical levels.
There’s a chart below, and some other information about sound levels. You’ll notice that for a musician in the orchestra, noise levels at a typical rehearsal or concert can cause hearing loss.
A brief explanation of Decibels
The intensity of a sound is a function of its sound pressure level. Sound pressure is measured in decibels (dB). The louder the sound, the higher the decibel level. The threshold of hearing is 0dB, the threshold of pain is about 130dB. Sounds with high dB levels can penetrate physical structures and rattle windows, vibrate dishes and, more importantly, destroy the very cells that allow the ear to perceive sound.
How hearing loss occurs
The inner ear contains thousands of tiny hair cells that respond to specific frequency ranges. They vibrate with the music. Excessive sound pressure levels weaken, then destroy these cells—permanently. How much is excessive? The chart below shows a list of common musical sound sources, their typical decibel levels and how long it takes hearing loss to occur.
The Occupational Safety and Health Admisistration (OSHA) regulates sound levels in industry. In 1983, OSHA incorporated the Hearing Conservation Amendment into the already existing Noise Exposure Standard. 85dBa is an 8–hour time weighted average that calls for a hearing conservation program to be in place if the 8hr average exceeds 85dba(50%).
The table below demonstrates that exposure to excessive sound levels can damage a person’s hearing. The emphasis in the sound sources shown here is on the musical environment. For comparison, some real-world sounds are: lawn mower, 90dB; power saw, 105dB; jackhammer at 3 feet, 120dB.
Sound levels and hearing loss
|source||Decibel level at close range||when hearing loss begins|
|normal piano practice||60-70|
|chamber music in a small auditorium||70-85|
|maximum recommended exposure||85||8 hours|
|timpani and bass drum rolls||106|
|symphonic music peak|
|120-137||less than 10 seconds|
|rock music peak||150||instant|
The costs of excessive noise
In addition to the physical pain one experiences at excessive dB levels, hearing loss due to excessive noise can cause tinnitus, often called “ringing in the ears”. Tinnitus can be painful and disorienting. The injury usually requires time away from loud noise and time off from work. OSHA estimates that, since 1971, occupational hearing loss compensations in the USA has exceeded $20 billion. Hearing loss also affects comprehension and learning, especially in children. See the National Institute of Occupational Safety and Health (NIOSH) article on Noise and Hearing Loss Prevention or visit www.dangerousdecibels.org for more information.
The basic rule: if you need to raise your voice to carry on a conversation, you are in an excessive sound environment.
The first action for reducing the damaging effect of excessive sound is obvious—reduce the source. In certain situations, however, this may be difficult. A cellist in an orchestra cannot turn around and ask the trumpet player behind him to play softer.
The second choice is to move away from the sound. Even a small adjustment can make a big difference, because the sound pressure level drops in proportion to the square of the distance. Again, for a musician on a stage with limited capacity, moving more than a few inches may be impossible.
The third option is usually the only one available to orchestra players: earplugs. You will also see acoustic shields on stage when the Symphony performs. These devices are for limiting directional sound from a single instrument and have little effectiveness for the ambient sound from the entire ensemble.