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La Scena Musicale - Vol. 12, No. 7 April 2007

Music and the Prevention of Hearing Loss

by Dr. Marshall Chasin / April 30, 2007

What distinguishes music from what we call “noise?” Although music (for instance symphonic music) and factory noise are considered aesthetically different, they are both based on the principles of sound vibration (the movement of air molecules received by the ear) and both, when excessively loud, can cause permanent hearing loss and, at times, even lead to a ringing in the ears called tinnitus.

Sound meter analyses show that industrial noise and music have similar spectra (sound energy) making it difficult to differentiate between the two. What sets music apart is its intermittent nature (i.e., loud periods followed by quiet moments or complete silences). During the early 1980s, Swedish researcher Erik Borg and his colleagues demonstrated that because music is comprised of sounds which change quickly, it allows the stapedial muscle (a muscle found in the middle ear of all mammals) to provide ample protection to the ear as it contracts. This intermittence is the reason why many researchers believe that music exposure may be slightly less damaging to the ear than an equivalent duration of exposure to factory noise. Acting like a small automatic earplug to the ear whenever loud sounds are heard, the stapedial muscle tightens up or contracts with the occurrence of louder intermittent sounds and temporarily prevents these sounds from getting through the ear successfully. Since drummers routinely hum just prior to, and during, a loud cymbal crash they activate the stapedial reflex and help protect themselves from hearing loss. The same cannot be said for workers who suffer the constant onslaught of noise emanating from factory equipment.

Although musicians are less likely to experience as much ear damage as factory workers, many studies indicate that they are still susceptible to hearing loss. For rock/pop musicians, the incidence is up to 30%, while the portion of classical musicians affected is as high as 52% due to longer playing and practicing periods. This leads to the conclusion that the duration of exposure to music and not just the music’s volume intensity impacts the degree of hearing loss.

Hearing protection

Traditional forms of hearing protection have been less than ideal as they cut down higher pitched sounds more than lower pitched ones, causing the music to sound muffled and dull. Wearing them was like turning down the volume on the right side of a piano keyboard but not the left. In 1988, a newer type of hearing protection was introduced. These earplugs, called ER-15, were custom-made for each user and promised to lower sound by exactly 15 decibels across the piano keyboard. Most musicians who use this protection can hardly feel them in their ears. Thus, a violin will still sound like a violin and a vocalist will still sound like a vocalist. By wearing the ER-15 one can be exposed 32 times longer to music and suffer no permanent hearing damage compared to someone not wearing it.

Various changes to a musician’s environment (examples below) can also be implemented to reduce hearing loss. Most of these ideas are inexpensive to implement and can be readily accomplished within the performance venue:

1. Elevate speaker-amplifier enclosures

A speaker enclosure, if touching the floor, will only generate noticable mid- and high-frequency energy as the low-frequency bass notes are absorbed into the floor and are lost to the listener. The usual remedy is to turn up the overall level of these lower frequencies, but, in the process, this unnecessarily increases their volume and can contribute to music-induced hearing loss. Elevating the speakers on stands (or simple milk crates) decreases the coupling with the floor and thereby increases the low-frequency output. This results in a flatter response that is also at an overall lower level.

2. Place treble brass instruments on risers

The bell of a trumpet is only a "guide" for the higher frequency notes. Mid- and low-frequency notes tend to "leak" out of the trumpet from all sides. However, the higher frequency notes behave very much like a laser beam and emanate along the playing plane of the trumpet. These same high-frequency harmonic notes are generally the most intense in the trumpet’s spectrum. Placing the trumpet on risers literally allows these damaging higher frequency notes to pass “over the heads” of the other musicians.

3. Position the orchestra/band back from the edge of the stage

Sound engineers find room acoustics challenging since there is less high-frequency energy than low frequency energy at the back of a concert hall. Placing the band back from the lip or edge of the stage will allow both the incident sound of the band and its higher frequency sound (up to 6 dB) to be reflected up off the lip of the stage to the audience. Not only will the music sound better, but the overall intensity level of the amplification will be decreased. This translates into less potential hearing damage to the audience, and less arm and wrist strain for the musicians.

4. Keep treble stringed instruments away from overhangs

If violins and violas are placed under an overhang (such as a music pit), the structure will absorb their higher frequency harmonic energy forcing the musicians to play harder in order to maintain their volume. This not only increases the overall intensity level of this large musical section but also increases the string musicians’ risk of arm or wrist damage. Moving them away from an overhang lessens their potential for hearing loss and other work-related injuries.

(c) La Scena Musicale