Hearing in Extreme Noise Environments

To understand the value of the TA100 product and how it achieves its superior performance over the products offered in the racing communications sector requires a brief discussion about the hearing process and how it is impacted by noise.

As you recall from your basic biology class in high school, there are three parts to the human ear: the Outer Ear, Middle Ear, and Inner Ear.The process of hearing is enabled by sound waves entering the ear canal and vibrating the eardrum. Sound waves create pressure on the eardrum, which is measured in decibels (dB). Loud sound creates greater pressure (more decibels). The softest sound that can be heard is rated at zero (0) dB.

According to The Occupational Safety and Health Administration (OSHA) guidelines, the maximum exposure time for unprotected ears per day is 8 hours at 90 dB. The chart shows the various dB measurements related to various sounds. Open exhaust race engines typically produce 130+ dB of noise, which clearly falls into the high danger zone for continuous exposure. Sustained exposure to loud sound can result in a medical condition called Tinnitus - which is a constant ringing in the ears and lowered ability to understand speech later in life. Tinnitus is irreversible and there is no known cure. Hearing aids will not help. Speech becomes garbled and incomprehensible. This loss is cumulative with time and exposure proportional to the decibel rating. For this reason, OSHA and other regulatory agencies require that workers exposed to loud sound have equipment designed to provide NOISE REDUCTION.A Noise Reduction Rating (NRR) is computed for each hearing protection product that helps determine the "before and after" impact of hearing in noisy environments. For example, if a set of ear plugs are labeled NRR 20, an individual in an environment with 100 dB of sound will only realize 80 dB when the product is worn properly.

One of the first reactions from first-time spectators at a NASCAR race is surprise at the noise level. Race cars are loud - really loud. A whole day at the track can be damaging to ears. Now consider the risk to the car driver, crew, track support personnel, safety personnel, broadcasters, and anyone else that is closer to the track surface than a fan sitting high up in their stadium seat. There is no debate that attendance or participation in racing creates a significant risk of hearing damage.

The challenge of dealing with this noise is most evident to designers of track public address systems. Crest Audio helped design the Las Vegas Motor Speedway. They had to design a computer controlled sound system that produced levels up to 117dB since ambient noise level in the grandstands at an auto race approaches 115dB. That's 125% of the OSHA guideline for workers in noise. To further make the point, consider that within a 2-mile radius of a NASCAR track, a basic sound meter shows noise levels up to 13dB higher than normal with noise levels ranging between 68 and 78 decibels. This level nearly achieves the OSHA 90 dB guideline for hearing protection! Another example of the amount of noise at an event is the availability of portable audio amplifiers, such as the Boosteroo which is designed to increase the volume of spectator scanners and radios to compensate for the extremely noisy listening environment.

As a result of the challenges of hearing in the very loud racing environment, audio product suppliers most commonly provide "muff style" headphones with their radios and scanners. The acoustic ear cup is designed to block out the ambient noise so that the user can hear the sound broadcast from the speaker embedded in the headset cup. Unfortunately, this approach has several significant drawbacks.

First, in order to block the sound, the cup must be pressed firmly against the head to create a seal. This is accomplished by use of a strap over or behind the head. When properly used, the cup can block as much as 27dB of noise which reduces the ambient noise heard by the wearer from 115dB to about 88dB (still at the OSHA safety cut off level). The big issue is that the headset cup is very hot and uncomfortable. It is also awkward when worn with a cap (common with most fans to block the sun). The end result is that the user will remove or loosen or shift the cup so that it is less uncomfortable - reducing its effectiveness! In the end, the lack of effective noise blocking causes the user to increase the volume of the radio which will cause even more hearing damage with prolonged use!

This problem was recognized long ago with workers who used cup-style headsets on the job. Because they were hot and uncomfortable they soon moved to ear-plugs to seal the ear canal from the ambient noise. The use of ear-canal noise blocking technology is a viable solution for the motor sports industry as well. Several in-the-ear audio headphones are available, but few if any offer adequate noise blocking. Here's why.

In-the-ear headphones have three basic components; a speaker, a sound pipe, and a foam tip that is inserted into the ear canal. When the foam is inserted properly into the ear canal, it creates a sound barrier that blocks external sound waves. As shown in this diagram, the surface area between the ear canal and the foam insert is significantly less than the surface area between the traditional ear muff and the head. As a result, foam inserts have a greater theoretical chance of producing superior sound isolation that do ear muff headsets.

The primary variables associated with optimum in-ear sound isolation headphones are the fit, flexibility and comfort of the foam insert and the design of the micro speaker and sound pipe that transmits into the ear canal. Foam insert fit is the most crucial element because each person's ear canal is unique - in size and length. Foam flexibility is also important because the ear canal moves when the jaw moves (talking, eating, etc.). And the foam material is important because it will be positioned in the ear canal for long periods of time, increasing the chance for irritation. The micro speaker must have sufficient output and frequency range that it provides quality sound reproduction. Finally, the means of attaching the tip to the earphone module is very important to ensure that the tip does not get stuck in the ear canal when the earphone is removed by the user.

The Trick Audio TA100 was designed by experts in the ear canal, specifically for listening in loud and noisy environments, to deliver "safer sound." The TA100 uses a patented foam tip that was initially developed for use with hearing aids. It also uses a patented tip attachment mechanism to help ensure safe removal from the ear. The speaker and sound pipe were engineered to offer optimum hearing across a broad spectrum that includes the spoken word as well as high fidelity music. The 3.5mm plug makes it compatible with most scanners, radios, and of course virtually all portable audio devices such as the popular Apple iPod. The TA100 is ideally suited both race scanning as well as listening to DVD players and MP3 players on planes, trains, or anywhere you want to listen to only what you want to hear.

For Your Safety

Do not wear TA-100 Earphones while driving a car, operating other motorized vehicles, riding a bicycle, or during any other situation where you need to have the full use of your hearing for your safety or the safety of others.

Wearing TA-100 Earphones reduces your ability to hear sounds from your environment and can create a hazard to you or others that could result in serious injury or death. These types of devices may be illegal in some areas.

Protecting Your Hearing:

Set the volume to the lowest setting before you insert the TA-100 Earphones into your ears. After the device is within your ear, and the Canal Tip has created its seal, adjust the volume to a comfortable level. Do not listen at high volume levels, which can lead to permanent hearing loss. Once a comfortable volume has been selected, do not increase the volume. As you continue to listen, your ears will adapt to the volume level, and if you increase the volume level, you may be causing damage to your ears without feeling discomfort.