Pure Tone Audiometer and Tympanometric Measurements
Sound generators that are used for assessment of peripheral hearing and can make a pure tone are termed and called as “audiometer”.
In hearing tests conducted by audiometers, commonly, hearing is measured in frequencies between 125 Hertz (Hz) and 8000 Hertz (Hz). For impedancemetric measurements, external auditory canal is occluded with the help of a special probe. When external auditory canal is occluded by a special probe, a closed area is created between tympanic membrane, external auditory canal walls and probe. During the measurement, pressure of external auditory canal is changed by using a pressure pump, and the change in transmittance of sound (probe tone) given to external auditory canal is determined during such pressure change. The graph obtained in this measurement is called “tympanogram”. Peak point of transmittance graph obtained in tympanogram is the pressure point where sound reaches its maximum transmittance, or to put it differently, where middle ear (tympanum) pressure is balanced with atmospheric pressure. Pressure level of this peak point also gives pressure level of middle ear. Tympanogram has different types seen in different pathologies. It is a method of assessment which is particularly indispensable in diagnosis, treatment and follow-up of middle ear pathologies. In addition, its feature of giving objective information about acoustic reflex increases the value of this measurement tool.