Types of Hearing Loss
Hearing loss can manifest in different degrees, ranging from mild to profound. It can also vary in terms of pitch or frequency. A series of hearing tests can determine the extent of your hearing loss compared to the average hearing ability of other adults.
Sound volume is measured in decibels (dB), with a soft whisper being around 15-20 dB and a jet engine reaching 120 dB. The softest sounds detectable are called thresholds. In adults with normal hearing, thresholds typically range from 0 to 25 dB across various frequencies. Speech testing is also conducted during these evaluations to assess your ability to hear specific words clearly. These tests help identify the type of hearing loss, which can be classified as conductive, sensorineural, or mixed.
Conductive hearing loss
Conductive hearing loss occurs when there is a problem in conducting sound to the inner ear and the cochlea. The issue may arise in the ear canal, eardrum, or middle ear (including the ossicles and Eustachian tube). The inner ear and auditory nerve remain unaffected in this type of hearing loss. Symptoms of conductive hearing loss are similar to other types, but individuals may experience sounds as muffled or excessively quiet.
Causes of conductive hearing loss can include:
- Outer or middle ear infections
- Complete blockage of the earwax
- Deterioration of the middle ear bones (ossicles)
- Otosclerosis (fixation of the ossicles)
- Perforated eardrum (tympanic membrane)
- Absence of outer or middle ear structures
Sensorineural hearing loss
Sensorineural hearing loss occurs when there is a problem with the sensory receptors in the cochlea of the inner ear or the auditory nerve. Most cases of sensorineural hearing loss are a result of abnormalities or damage to the hair cells in the cochlea. This condition hampers the normal transmission of sound signals to the brain, resulting in hearing loss.
Individuals with sensorineural hearing loss may experience muffled speech, tinnitus (ringing in the ears), difficulty hearing in noisy environments, or problems with speech clarity.
Causes of sensorineural hearing loss can include:
- Congenital conditions where hair cells are abnormal since birth
- Damage to hair cells due to genetics, infection, drugs, trauma, or prolonged exposure to loud noise
- Age-related hearing loss (presbycusis)
Mixed hearing loss
Mixed hearing loss occurs when a person experiences both sensorineural and conductive hearing loss. This means there is an issue in the inner ear as well as the outer and/or middle ear.
The conductive component of mixed hearing loss may be temporary or permanent, depending on the underlying cause. Medical management can sometimes address the conductive part, while hearing aids are commonly recommended as a treatment option.
