Output power amplifier: The amplifier makes the signals of the oscillator larger than the original and with very little alteration and noise. Hearing level attenuator: The level of the signal from the audiometer has to be controlled to a range of 110 – 120 dB, this is the function of the attenuator, which has to be done in steps of 5 dB, and also it has to be accurate (Khandpur, 2003). Output transducers: There are three types of transducers: ear phones, bone vibrator and loud speakers. The earphones are very important because is the final exit of the frequencies of sound, so the earphones must have the same uniformity of frequency over time, and also input and output frequencies should be the same and lastly should be able to project high output sounds. Bone vibrators are used in a certain frequency range. There are not used in low frequencies because the sounds are not clean enough. The loud speakers are used on hearing test for children. Hearing Test: An audio-metric hearing test is done by a certified audiologist in a sound-proof testing booth. First of all the audiologist has to explain the patient that he has to put on the headphones and that every time he or she
hears a tone then he or she has to press a button. Next, the audiometer is going to present one frequency at varying intensities until the person no longer hears it, and the test is going to continue that way but with different frequencies ranging from 250 Hz to 8000 Hz, with a level of decibels from 0-110 dB. The audiologist (fig 1) defines the hearing threshold of the patient by recording the lowest level that the patient responded to in a chart called an audio-gram Then the hearing loss is categorized as mild, moderate, severe or profound as in Table 1 (Khandpur, 2003). TREATMENT FOR OTOSCLEROSIS Even in a mild case of hearing loss, a good option will be to use hearing aids which will be helpful to the person to hear by amplifying nearby sound; but in many cases an stapedectomy (which is a surgery that uses a prosthetic device to help the sound waves get into the inner ear), it may be the only option.