Types of Hearing Loss

There are three types of hearing loss which are determined by the location or site where the ear’s function is abnormal. These types of hearing losses include conductive, sensorineural, and mixed hearing losses. The onset of hearing loss is considered when diagnosing hearing impairment. Hearing loss is also measured by severity and there are different categorizations based on the severity of the hearing loss.

Conductive Hearing Loss

A conductive hearing loss is caused by “disorders associated with an abnormality in the reception and transmission of sound through the external auditory canal, tympanic membrane, and middle ear space” (Hilger, Paparella, & Anderson, 1984, p. 25). To further explain, when sound traveling through the outer ear and middle ear space is impeded, there is an attenuation or reduction of hearing ability. The most common cause of conductive hearing loss is due to middle ear infections or otitis media (Flexer, 1996). Other causes of conductive hearing loss may include: cholesteatoma (a pseudotumor in the middle ear area), otosclerosis (growth of spongy bone most commonly on the stapes), fractures of the middle ear bones, genetic causes, perforation of the tympanic membrane, and tumors such as polyps or granulomas (Martin, 1996, p. 273). Medical intervention or hearing aids are typically prescribed to correct conductive hearing loss (Flexer, 1996; Flexer & Richards, 1998).

Sensorineural Hearing Loss

Sensorineural hearing losses are located in the cochlea or auditory nerve. In the cochlea, the hair cells, which are developed during the first three months of gestation, must last an entire lifetime (Brownell, 1999). Thus, if these hair cells are damaged, the damage is irreparable (Flexer & Richards, 1998). Since a limited number of hair cells are present in the cochlea, the absence or malformation of functioning hair cells in the cochlea affects hearing (Brownell, 1999, p. 16). Sensorineural hearing loss can be caused by a variety of agents. For instance, damage to the hair cells can be caused by disease, anoxia, noise exposure, the aging process, ototoxic medication, trauma, or hereditary causes (Meyerhof, Liston, & Anderson, 1984). Lesions such as tumors on the auditory nerve also cause sensorineural hearing loss (Martin, 1996).

Mixed Hearing Loss

The third type of hearing loss is a mixed hearing loss. This particular type of hearing loss occurs when both a sensorineural and conductive hearing loss are present (Epstein, 1996). For instance, an individual may have an existing sensorineural hearing loss, but may have otitis media as well (Flexer, 1996, p. 37).

Onset of Hearing Loss

Hearing loss can occur at different times in one’s life. Hearing loss that is acquired before the approximate age of three years is called a prelingual hearing loss. This type of hearing loss occurs before, during, or shortly after birth (Flexer & Richards, 1998) and is present before the acquisition of speech and language (Epstein, 1996). A postlingual hearing loss occurs after the acquisition of language (Epstein, 1996).

Degree of Hearing Loss