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By Helene Norris


The audiometer is a machine used by audiology centers and ENT specialists to measure hearing loss in patients. More often than not, it is a part of the audiometry test equipment used for administering various tests. Audiometers now available in the market come in both hardware and software form.

The hardware version is a simple machine that produces pure tones at controlled intensities. During hearing loss evaluations, the machine's output is heard by the subject in one ear at a time through a pair of headphones. The subject has a feedback button that enables them to respond when they hear the tone.

Audiometers may be standalone machines or can be integrated with a computer that controls it and offers a full suite of software tools and functionality. These devices come in many different types and use varying technologies. For example, some are bone-conduction systems while others are air-conduction based. It may be handheld, portable or a full-fledged machine intended for use in a single location.

Software-based systems function in pretty much the same way, sending out a tone to the subject on a headphone and collecting feedback through a button. The difference is in the way the tone is generated. In this case, the software merely sends out stored tones to the computer's sound card.

Audiometers built as a physical machine are more expensive, but provide the high degree of accuracy that hospitals, researchers and audiology centers need. Regular calibration is still essential to ensure the tone heard and the level shown in the display match each other. Proper calibration is also necessary to ensure a global standard for testing and measurement of hearing levels.

Audiometry software installed on desktops or laptops can be used at home by anyone, and it is relatively affordable. It is more difficult to calibrate the software, which also means that accuracy is hard to achieve. It is, however, still good enough to allow a subject to self-test and determine if their hearing is normal or needs medical treatment.

The purpose of this arrangement, regardless of whether it is software or a physical device, is to pinpoint the exact audio level at which the subject stops responding. This allows the physician to diagnose the problem, if any, and provide treatment. Apart from actual ear cleaning to clear obstructions, the subject may also need to take ear drops. If the problem is more serious, a hearing-aid or surgery (or both) may be needed.

Another major application for audiometers is industrial audiometric testing. The actual process is pretty much the same as the one described above. One of the key differences is the fact that patients don't visit the clinic. Instead, a mobile lab with the required equipment and technicians comes to the industrial facility for testing the hearing levels of workers who are constantly exposed to noise.

The tests performed on industrial workers are not just for evaluating their personal hearing loss. The results allow the company to identify trends and add more noise-muffling technology if a lot of workers are showing signs of weakened hearing ability. It may also be required under group health plans. Either way, an audiometer used in an industrial environment must be calibrated to a high degree of precision, which means it must be accurate to within a few fractions of a decibel.




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