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Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear . If a conductive hearing loss occurs in conjunction with a sensorineural hearing loss, it is referred to as a mixed hearing loss.
Loss of hearing caused by changes in the inner ear is called sensorineural deafness. Hearing loss that results from changes in the middle ear is called conductive hearing loss. The middle ear contains three tiny bones that help transfer sound from the eardrum to the inner ear. Some forms of nonsyndromic deafness involve changes in both the ...
PTA can be used to differentiate between conductive hearing loss, sensorineural hearing loss and mixed hearing loss. A hearing loss can be described by its degree i.e. mild, moderate, severe or profound, or by its shape i.e. high frequency or sloping, low frequency or rising, notched, U-shaped or 'cookie-bite', peaked or flat.
The shape of the audiogram resulting from pure-tone audiometry gives an indication of the type of hearing loss as well as possible causes. Conductive hearing loss due to disorders of the middle ear shows as a flat increase in thresholds across the frequency range. Sensorineural hearing loss will have a contoured shape depending on the cause ...
A tone at the frequency of 4000 Hz is presented for 60 seconds at an intensity of 5 decibels above the patient's absolute threshold of hearing. If the patient stops hearing the tone before 60 seconds, the intensity level is increased by another 5 decibels with the procedure repeated until the tone can be heard for the full 60 seconds or until no decibel level can be found where the tone can be ...
Conductive hearing loss; Conductive hearing loss is present when the sound is not reaching the inner ear, the cochlea. This can be due to external ear canal malformation, dysfunction of the eardrum or malfunction of the bones of the middle ear. The eardrum may show defects from small to total resulting in hearing loss of different degree.
A conductive hearing loss along with middle ear disease is most commonly seen in patients with Pfeiffer syndrome; although, there have been reports of mixed hearing loss as well. The hearing loss is most typically caused by stenosis or atresia of the auditory canal, middle ear hypoplasia and ossicular hypoplasia (Vallino-Napoli, 1996).
With conductive hearing losses, the latencies for air are shifted when compared to the latencies of bone-conduction. Mauldin & Jerger (1979) found that for adults, the Wave V latencies derived from bone-conduction ABR are approximately 0.5 ms longer than the same intensity level of air conduction. [ 5 ]