Diagnosis of hearing loss
Identification of a hearing loss is usually conducted by a general practitioner medical doctor, otolaryngologist, certified and licensed audiologist, school or industrial audiometrist, or other audiometric technician.
Subjective: Objective: A case history (usually a written form, with questionnaire) can provide valuable information about the context of the hearing loss, and indicate what kind of diagnostic procedures to employ.
This evaluation method assesses an individual's ability to comprehend speech amidst background noise.
Individuals with hearing loss typically experience difficulty in understanding speech, particularly in environments with high levels of noise.
Other electrophysiological tests, such as cortical evoked responses, can look at the hearing pathway up to the level of the auditory cortex.
The severity of a hearing loss is ranked according to ranges of nominal thresholds in which a sound must be so it can be detected by an individual.
[4] An additional problem which is increasingly recognised is auditory processing disorder which is not a hearing loss as such but a difficulty perceiving sound.
The eardrum may show defects from small to total resulting in hearing loss of different degree.
Dysfunction of the three small bones of the middle ear – malleus, incus, and stapes – may cause conductive hearing loss.
The most common reason for sensorineural hearing loss is damage to the hair cells in the cochlea.
The peripheral ear and the auditory nerve may function well but the central connections are damaged by tumour, trauma or other disease and the patient is unable to process speech information.
The shape of an audiogram shows the relative configuration of the hearing loss, such as a Carhart notch for otosclerosis, 'noise' notch for noise-induced damage, high frequency rolloff for presbycusis, or a flat audiogram for conductive hearing loss.
In conjunction with speech audiometry, it may indicate central auditory processing disorder, or the presence of a schwannoma or other tumor.
