Hearing loss is described by varying degrees, not percentages. Hearing loss may be mild, moderate, moderately-severe, severe or profound and vary across pitches. It is determined by a hearing test as the amount of volume loss you experience compared to an average of many other adult listeners with normal auditory systems. The volume, or intensity, of sounds you hear is measured in decibels (dB HL), 0 dB HL being the softest whisper and 120 dB HL being a jet engine. The softest sounds one can hear are called thresholds. Normal hearing thresholds for adults are considered to be 0 dB HL to 25 dB HL.
Conductive hearing loss is caused by damage to the outer or middle ear. With a conductive loss, sound waves are blocked as they move through the outer or middle ear. Since the sound cannot be conducted efficiently, the sound energy that reaches the inner ear is weaker or softer. A conductive loss can result from infection, excessive earwax buildup, fluid in the middle ear, damage to the middle ear bones, a perforation of the eardrum or a foreign body in the ear canal.
Medical management such as medication or surgery may be an option. However, in some cases, there is no available medical management. Therefore, hearing aids are recommended.
Signs/Symptoms May Include:
- Perceiving speech and other sounds as faint or muffled
- Ear pain or discharge from the ear
- Redness or swelling of the outer ear
- Pressure or fullness in the ear
Sensorineural hearing loss is caused by damage to the inner ear and/or auditory nerve. Sound waves travel normally through the outer and middle ear, however, the inner ear is unable to pick up the vibrations or is unable to send the vibrations to the brain. The inner ear (cochlea) hair cells may be damaged and it usually occurs in both ears. A sensorineural loss can result from infection, disease, certain drugs, excessive noise, birth defects, genetics and aging.
90 to 95% of all adult hearing losses have no medical management. Hearing aid amplification is the best intervention. This type of loss is permanent and irreversible but HEARING AIDS will HELP!
Signs/Symptoms May Include:
- Perceiving speech and other sounds as distorted or unclear
- Difficulty hearing certain pitches (usually high pitches)
- Hearing a ringing or buzzing sound that is constant or periodic
- Difficulty understanding speech in quiet and even more so in background noise
Mixed hearing loss is caused by damage to the outer/middle ear and the inner ear. Typically, sound waves are not conducted efficiently to the inner ear, and once they reach the inner ear, the vibrations cannot be picked up or sent to the brain. Therefore, a mixed hearing loss is the combination of a conductive and sensorineural hearing loss.
Signs/symptoms may include all of the above.
Central hearing loss is caused by damage to the auditory nerve or hearing centers. Sound waves are transmitted normally through all three parts of the ear, however, the auditory nerve may not be able to send the electrical impulses to the brain or the hearing centers of the brain may not receive the signals correctly. A central hearing loss can result from head injuries, absence or malformation of the auditory nerve, disease or tumors.
Signs/Symptoms May Include:
- Unable to detect sound
- Detecting sound but not being able to understand or process it