Introduction

The etiology (cause or origin) of hearing loss is often hard to pinpoint. Genetic, environmental, multi-factorial, and unknown causes of hearing loss are common. For some, an over-accumulation of cerumen (ear wax) can lead to blockage in the ear canal that leads to hearing loss.  Most hearing losses are caused by multiple factors such as a degeneration of the auditory system due to age (presbycusis) and/or excessive noise exposure.  Audiologists and other health-care professionals involved in the diagnoses of hearing loss are well-trained in formulating a treatment and/or rehabilitation for the patient.

Hearing loss is often categorized by where and what section(s) of the auditory system is affected.  Hearing loss is usually categorized into one of the following: conductive, sensorineural, and mixed hearing loss.

Conductive Hearing Loss

Conductive hearing loss occurs when the transmission of sound (acoustic and mechanical) is weakened somehow during its path from the outer ear through its middle ear.  Patients that experience a conductive hearing loss often say that it sounds like they are "plugged up".

Examples of Conductive Hearing Loss:

• Obstructed ear canal - excessive/occluding wax, foreign body in the ear canal
• Otitis Externa - infection in the ear canal
• Middle ear issues - Otitis Media (Infection in the middle ear), fluid in the middle ear, allergies, poor Eustachian tube function, Perforated Eardrum, benign tumors, dislocated ossicles (malleus, incus, or stapes).
• Absence or malformed our ear, ear canal, or middle ear

Sensorineural Hearing Loss

A loss or distortion of sound transmission as a result of damage to the inner ear hair cells or any of the pathway from the inner ear to the auditory cortex of the brain is often diagnosed as a sensorineural hearing loss.  Sensorineural hearing loss is a permanent and irreversible type of hearing loss more often than not.  Patients with this type of loss often say that speech sounds muffled, distorted and unclear.  The severity of the hearing loss often determines difficulty of speech understanding, especially in noisy environments such as restaurants, meetings, and conference halls. If you experience sudden onset hearing loss, it is very important to seek help by a physician, preferably an ear specialist (otolaryngologist, otorhinolaryngologist, otologist, neuro-otologist, ENT) within 24-48 hours of onset. The effects of the hearing loss MAY BE treated with medication.

Examples of Sensorineural Hearing Loss:

• Presbycusis - age-related hearing loss with a gradually progressive inability to hear. High frequencies are usually affected first.  These individuals may find that speech sounds muffled and unclear and often ask the speaker to speak up & clearly.  This type of loss is very common and affect a third of people 65-75 years old and up to half of people 75 and older.
• Ototoxic Medications - Certain drugs can damage the fidelity of the inner ear system which can lead to either temporary or permanent damage depending on the dosage and the actual drug.
  • Certain Antibiotics such as aminoglycosides (gentamicin, vancomycin, etc.), erythromycins, and minocycline.
  • Diuretics
  • Salicylates
  • Antineoplastics
  • League for the Hard of Hearing's comprehensive list of Ototoxic Medications, click here!
• Acoustic Trauma - excessive and prolonged exposure to noise can damage your auditory system
• Inner Ear Infections - such as meningitis, herpes, mononucleosis, labyrinthitis, measles, mumps, cytomegalovirus (CMV) can induce hearing loss.
• Head Trauma - trauma to the temporal bone (houses the peripheral auditory system) can affect the function of several parts of the ear, especially the auditory nerve
• Meniere's Disease - usually diagnosed by a trilogy of symptoms: roaring tinnitus (ringing in the ears), fluctuating low frequency sensorineural hearing loss, and severe vertigo.  Unknown etiology.  Sometimes attributed to endolymphatic hydrops (increased pressure/fluid in the cochlear of the inner ear)
• Acoustic Neuroma - tumor on the auditory nerve