Auditory expert Dr. Andrew J. Vermiglio answers questions about protecting your ears

GRAMMY.com

May is Better Hearing and Speech Month, and an appropriate time to address one of the biggest health issues that engineers, producers and musicians face on the job — noise-induced hearing damage.

With more than 32.5 million people in the United States already dealing with hearing loss problems, 30 percent have experienced permanent loss from excessive sound exposure, with many also suffering from an annoying ringing sound in their ears. In recent years, House Ear Institute researchers have studied the effects of on-the-job exposure among music and audio professionals and have found a significantly greater prevalence in the incidence and early onset of high frequency noise damage compared with people working in other professions. It is such a pervasive issue in the music industry that House Ear Institute has committed much of its nonprofit community outreach funding over the last 11 years to help educate industry professionals and address common hearing issues.

In recognition of Better Hearing and Speech Month, House Ear Institute audiologist Dr. Andrew J. Vermiglio, Au.D., sheds some light on some of the most frequently asked questions and concerns that music industry professionals have regarding hearing loss.

What are the implications of a hearing loss due to exposure to high levels of sound?
In the early stages, you may experience a temporary ringing in the ears or "tinnitus." Additionally, you may notice a decreased ability to understand conversation in a noisy environment such as a crowded restaurant. Conversation in a quiet environment may seem unimpaired.

As the damage to the structures in the hearing organ (cochlea) increase, the ability to understand speech in a noisy atmosphere may further decrease and the ability to understand speech in a quiet environment may start to degrade. Additionally, the ability to hear high frequency sounds may start to decrease. The high frequency content of speech sounds includes the consonant sounds "s" and "f" and advanced stages of hearing loss due to exposure to high levels of sound will result in a decreased ability to perceive the consonant sounds in speech. The ability to hear the lower frequency vowel sounds will be less affected. This is why individuals with a noise-induced hearing loss may say things like, "You don't have to yell, I can hear you" or "I just didn't understand what you said." Some people may think that their hearing difficulties are solely related to inattention to conversation when the reality may be that some portion of the sounds of speech and the environment are no longer audible.

A normal hearing person may experience a great deal of frustration when conversing with a hearing impaired person. At the same time, the hearing impaired person may be oblivious to what he or she is missing.

As a noise-induced hearing loss progresses, the ability to hear high frequency sounds will further decrease. Sounds will tend to sound muffled or "muddy." Critical listening will be affected by an inability to detect the high frequency content of sound. For sound engineers, this may lead to a situation where they are mixing to compensate for their own hearing loss. This can lead to a sound mix with an exaggerated high frequency content. Furthermore, it may lead to undesirable extraneous high frequency sounds present in the mix. These extraneous sounds may be heard by normal hearing listeners, while being undetected by the hearing impaired producer or engineer.

How can I reduce the risk of a high sound level-induced hearing loss?
As a rule of thumb, if you find yourself in an environment where you must raise the level of your voice in order to be heard, you are in a potentially hazardous environment for hearing. The harmful effects of exposure to loud sounds are based on two factors: the level of the sound and the length of exposure time. Therefore, it is very important to limit sound pressure level and limit the amount of exposure to hazardous acoustic environments. A reduction in the level of the sound may be accomplished through the use of properly selected earplugs. Additionally, it is a good idea to obtain a simple sound level meter and actually measure the sound level in your environment. If you know that you will be exposed to high levels of sound on a given day it is a good idea to limit exposure to other activities that may add to your exposure such as riding a motorcycle, operating power tools, driving a speed boat, or exposing yourself to loud music.

What is the best way to monitor the status of my hearing ability?
The standard audiogram or pure tone threshold test has been used for several decades to monitor hearing status. Specifically, it measures the lowest level that you can hear a pure tone stimulus. Frequencies measured are from 125 or 250 Hz to 4,000 or 8,000 Hz. The beginning stages of a sound-induced hearing loss will appear as a notch or reduced sensitivity at 3,000, 4,000 or 6,000 Hz.

While the audiogram is an important measure of hearing sensitivity for frequency specific stimuli, it is not as sensitive as some other tests to the earliest effects of loud sound exposure. Detection of otoacoustic emissions, or the sounds generated by the outer hair cells in the cochlea, is one of these tests. The outer hair cells inside the cochlea are generally the first structures to become damaged when exposed to high levels of sound. An otoacoustic emissions test may show signs of outer hair cell damage before it is seen in the audiogram.

A Hearing In Noise Test (HINT) is a measure of speech recognition in noise ability. This ability may degrade even though the audiogram is within normal limits. Speech recognition in noise ability is also related to the function of the outer hair cells.

Is there anything else that I should know about?
Yes. Never use a cotton swab to clean inside the ear canals. Doing so may result in abrasions in your ear canal walls and you may not be aware of this condition. Earplug usage in a damaged ear canal may further aggravate the damaged lining of the canal. Furthermore, using cotton swabs in your ear canals may help create an actual plug of earwax that can reduce your ability to hear.

Finally, if you work around loud sounds you should have your hearing tested once a year. If you notice a change in your ability to hear, you should obtain a hearing evaluation from an audiologist. And, remember that not all hearing losses are from exposure to loud sounds. Some hearing losses are due to other medical conditions that may require immediate attention.

To learn more about hearing health and House Ear Institute's Sound Partners hearing conservation outreach services, visit www.hei.org or e-mail soundpartners@hei.org.

(Andrew J. Vermiglio, Au.D., is a senior research associate at the House Ear Institute in the Dept. of Human Communication Sciences and Devices. On evenings and weekends, Dr. Vermiglio is a professional drummer. You can address further questions to him at avermiglio@hei.org.)