|
How to minimize noise music induced hearing loss.
Music, can be fun but it does present dangers to our hearing,namely music induced hearing loss.With that in mind, it is wise to be aware of the hazards and take precautionary measures to mitigate the risk. Although there are numerous strategies to minimize the danger, this article concentrates on five key areas. HummingThe first strategy in minimizing the negative effects of noise/music is humming, which utilizes the tools Mother Nature gave us. When the stapedial muscle contracts upon intense sounds, it tightens the ossicular chain, slightly attenuating the sound transmitted to the cochlea. The effect may differ from person to person and is the basis behind stapedial (acoustic) reflex testing in clinical audiometry. Absent reflexes may be an indicator of middle ear dysfunction, and is typical with more severe hearing losses.From an evolutionary perspective, the stapedial reflex contracts with our own voice; without it, our voice may be perceived as being too loud. Research has indicated that this reflex may provide some relief from noise and music exposure, as well. For example, humming (which elicits the stapedial reflex) just prior to a loud sound and sustaining the hum over the length of the sound will afford some protection. How to enjoy MUSICPrior to 1970, available research suggested that only two factors affect whether one could suffer a hearing loss from noise/music exposure. The first was the duration of the exposure and the other was the intensity. For example, a 100 dBA noise for 10 minutes would not create a hearing loss, but a 100 dBA noise for 10 hours would.Specifically, a relationship exists called the “3 dB exchange rate.” In this scenario, 85 dBA for 40 hours a week is identical exposure to 88 dBA for only 20 hours a week, which is identical to 91 dBA for only 10 hours a week and so on. In other words, for every increase of 3 dBA, the effective exposure doubles, and one only needs to be exposed for half the time before the same damage occurs at a level of exposure that is only 3 dBA less intense. TTSStudies show a resolution of TTS (temporary threshold shift) caused by noise or music after about 16—18 hours. This is the primary reason for not testing an industrial worker until after he/she has been exposure-free for this period. Resolution of the TTS does not guarantee that all of the subtle aspects of one’s hearing have returned to normal. For example, tinnitus may last for three or four days after a particularly noisy event, it may also be a sympton of music induced hearing loss.. However, after a 16—18 hour period, hearing is almost back to the pre-exposure state. Moderation in the form of limiting one’s exposure to noise or music for a day or two has even been enshrouded in standards. For instance, some hearing conservation standards use the “on-off” rule, whereby credit is given for the “off” times where there is no significant noise or music exposure, thus reducing the overall exposure rating. A good rule of thumb is to alternate your noisy days with quiet ones. Attending a rock concert on Friday may result in less damage from noise exposure if you don’t mow your lawn until Sunday.A Study of TTSZakrisson et al. (1980) studied the effects of Bell’s palsy on noise exposure. Bell’s palsy, a unilateral condition that is almost always temporary, is usually seen as a drooping or weakness of one side of the face. During the active stage, hearing is maintained; however, the stapedial reflex is temporarily de-innervated. Zakrisson and his colleagues exposed patients with Bell’s palsy to a high level of noise and measured hearing to determine the influence of the stapedial reflex abnormality on threshold. The results indicated that the temporary threshold shift (TTS) was greater on the Bell’s palsy side. That is, the ear with the active (and protective) stapedial reflex caused the ossicular chain to tighten, thus affording protection to that ear. In contrast, the Bell’s palsy ear had no such protection. Industrial workers and musicians who suffer from Bell’s palsy should be counseled to avoid noise/music exposure during the active phase.In another study from the same laboratory in Sweden, the stapedial muscle from one ear of rabbits was resected (Borg et al., 1983). The other ear was left unaffected. The rabbits were exposed to intense sounds and a permanent hearing loss was created. Again, the ear with the functioning stapedial reflex offered protection from the noise. In humans, it is difficult to study the long-term permanent effects of noise and music induced hearing loss, vis-à-vis the stapedial reflex, but these studies and others on laboratory mammals suggest that the stapedial reflex can be quite useful in minimizing hearing loss from noise/music.Shielding The Noise SourceShielding a noise source or increasing the distance between the noise source and listener can have beneficial long-term effects. In the musical setting, elevation of the trumpets ensures that much of the damaging mid- and high-frequency energy goes over the heads of those musicians downwind. Mid- and high-frequency energy emanates from the trumpet bell in a very directional pattern, whereas the less intense lower-frequency, energy “leaks” out of the sides of the trumpet and can be picked up in virtually any direction. Placing the trumpet players on risers can be quite beneficial to the musicians surrounding them.Another obvious alternative is to move the cymbals away from the other musicians. The high hat cymbal tends to be the most damaging element in the rock band and is typically on the left side of the drummer. It is not unusual to find that the left ear hearing of a drummer is worse than the right. If a musician usually stands to the left of the drummer, he/she should move forward or to the right side (and, of course, they should be humming).In a classroom or rehearsal room, damping materials such as carpeting or three-dimensional artwork can be placed on walls and floors. The small holes in three-dimensional artwork absorb some of the energy, thus reducing annoying echo and reverberation. Band and orchestra directors can use a moveable heavy curtain across the blackboard at the front of the classroom. Hearing ProtectionHearing protection can be approached in two different ways. The first is to use a passive acoustic network that attenuates or lessens all sounds uniformly. The second is to use a modified hearing aid called an ear monitor. The ear monitor is essentially a mini-loudspeaker that is custom-made for the musician to replace the big “wedge” loudspeakers on stage. The ear monitors also act to attenuate the environmental noise and music, and may help to minimize noise induced hearing loss.Uniform acoustic hearing protection is available which attenuates the low-frequency bass notes at the same amount as the higher-frequency treble notes. Music still sounds like music, only less loud. One popular model is the ER-15 which provides precisely 15 dB of attenuation across the frequency region. Special earplugs can be quite useful for most musicians and concertgoers, regardless of type of music.
|
