Hearing Impairment Hearing loss is one of the most common complains of patients presenting to the otolaryngologist. The evaluation of hearing loss involves a detailed case history, a physical examination, and audiologic testing
Types of Hearing Impairment 1.Conductive Hearing Impairment 2.Sensory-Neural Hearing Impairment 3.Mixed Hearing Impairment
Otologic Examination ? Case history (thorough) ? Physical examination ? Tuning fork test ? Examination of the cranial nerves ? Examination of eye movement ? Examination of the face ? More neurological testing should be tailored to the specific pathology being considered.
Tuning Fork Test ? Rinne Test By using a 512 Hz tuning fork, Rinne test examines whether the tone is louder alongside the auricle (air-conduction) or when pressed against the mastoid process (bone conduction). The Rinne test result is positive if the tone is louder by air and negative if it is louder on bone. Negative Rinne result indicates a conductive hearing loss of more than 20 dB. When there is no difference in loudness, the result is equivocal and indicates a conductive hearing loss of 20 dB.
? The Weber Test The Weber test is performed by placing the struck tuning fork on the fore head or upper incisor teeth. This test lateralize to the ear with the conductive hearing loss or in the case of bilateral disease to the ear with the greatest conductive hearing loss. When the Weber test is properly performed, it can detect conductive losses of as little as 5-10 dB.
Audiologic Examination ? Case history review ? Inspection of the patient ? Otoscopic examination ? Impedance battery ? Reflex testing ? Testing for the Eustachian tube function ? Pure tone audiometry ? Speech test ? Electrophysiologic examination
I. Behavioral Tests ►Puretone Audiometry ♦Puretone audiometry (PTA) is our tool to determine whether hearing is normal or impaired. It is a subjective test that is considered as the first and the most fundamental measure of hearing. Puretone audiometry (PTA) is used to quantify the degree and the type of hearing loss and to gain information into the nature of the cause in some cases.
Application: 1. To measure the hearing status prior to and after surgery. 2. Monitor hearing of those working in industry. 3. Monitor hearing of patient receiving chemotherapy. 4. General indicator of the power of amplification needed for the hearing aid adjustment. 5. Screening purpose.
Frequency It can be defined as the pitch or rapidity of the sound. The young healthy normal ear can perceives a wide range of frequencies from 20 pressure variations per second (20 Hertz or Hz) up to 20,000 pressure variations per second (20 kHz) but it is more sensitive to human speech frequency range. The tested frequency scale Octave intervals - 125Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz Mid-octave intervals – 750 Hz, 1.5 kHz, 3 kHz, and 6 kHz.
Intensity It can be perceived as loudness. The human ear can respond to a wide range of sound pressures The decibel scale Micropascals (µPa) Decibels (dB) 100.000.000 Threshold of pain 140 10.000.000 Jet aircraft on take off 120 1.000.000 Road drill 100 100.000 Loud shout 80 10.000 normal conversational 60 Office background noise 1.000 Quiet living room 40 100 whispering 20 20 Threshold 0
MODIFIED GOODMAN (1965) BY CLARK (1981) Hearing Level (dB HL) (500, 1000, 2000 Hz) Classification -10 - 15 Normal 16 - 25 Slight 26 - 40 Mild 41 - 55 Moderate 56 - 70 Moderately Severe 71 - 90 Severe >90 Profound
JERGER (1980) Hearing Level (dB HL) classification 20 Normal 20 - 40 Mild 40 - 60 Moderate 60 - 80 Severe 80 - 100 Profound