Hearing Loss

About Hearing Loss

Hearing loss is a sudden or gradual decrease in how well you can hear. It is one of the most common conditions affecting older and elderly adults. Approximately one in three people between the ages of 65 and 74 has hearing loss and nearly half of those older than 75 have difficulty in hearing.

People themselves do not realise that they have hearing loss even though family members, office colleagues and friends may be quite aware of it. For some all sounds will be heard, but its volume is low. For others, speech and music sound will be slightly distorted. Many actually find it difficult to clearly hear specific sounds such as conversation both in typical environments and from a distance.

Types of hearing loss

  • Conductive hearing loss: This type of hearing loss is directly associated with inability of or malfunctioning of outer or middle ear. In this condition, either outer ear or middle ear or both, fails to collect and carry forward the sound waves emitted from a source. This condition, in most of the cases is treatable; however, the method of treatment depends upon the actual problem.
    It can be caused by earwax, an ear infection, a punctured eardrum, a buildup of fluid, or abnormal bone growth. It is more common in children and indigenous populations. Medical interventions and technologies are often used to treat conductive hearing loss. Technologies such asBone Conduction Hearing Aids and Bone Anchored Hearing Devices can help reduce the effects of conductive hearing loss.
  • Sensory hearing loss: Sensorineural hearing loss occurs when the part of the ear that transforms sound to electrical information (the cochlea) and sends the information to the brain (auditory nerve) is damaged or malfunctions. It is permanent.
    It can be genetic or caused by the natural aging process, diseases or exposure to noise and certain kinds of chemicals. Managing exposure to damaging noise prevents noise-induced hearing loss and limits further deterioration of existing hearing loss. Auditory Neuropathy is a form of sensorineural hearing loss where the auditory nerve is damaged or malfunctions.

Technologies such as hearing aids, cochlear implants, hybrid cochlear implants, and auditory brainstem implants can help reduce the effects of sensorineural hearing loss.

  • Mixed Hearing Loss: A mixed hearing loss occurs when both conductive and sensorineural hearing losses are present. The sensorineural component of the hearing loss is permanent, while the conductive component may be permanent or temporary.
    For example, a mixed hearing loss can occur when a person with age-related hearing loss also has a middle ear infection.

Degree of hearing loss

  • Normal hearing (0-25 dB): At this level, hearing is within normal limits.
  • Mild Hearing Loss (26 – 40 dB): A person with a mild hearing loss might face difficulty in some situations like Group Discussions, Whispering.
  • Moderate Hearing Loss (41 -55 dB): A person with a moderate hearing loss may hear some speech sounds but soft sounds are hard to hear.
  • Moderately Severe Hearing Loss (56 – 70 dB): A person with a moderately severe hearing loss may hear almost no speech when another person is talking at a normal level.
  • Severe Hearing Loss (71 – 90 dB): A person with severe hearing loss will hear no speech when a person is talking at a normal level and only some loud sounds are audible.
  • Profound Hearing Loss (>90 dB): A person with a profound hearing loss will not hear any speech and only very loud sounds.

Causes of hearing loss:

    Some medications cause irreversible damage to the ear, and are limited in their use for this reason. The most important group is the amino glycosides (main member gentamicin). Many antimalarial, antidiuretic and antibiotic drugs have hearing loss as a side-effect.
    A persistently noisy environment with noise levels exceeding 85 Db is estimated to cause more than half the hearing loss cases. Noisy machines in households or factories, car stereos and horns, vehicles, children’s toys, incessant use of earphones are some common environmental factors which cause hearing loss at low and high frequencies. A sudden short-term exposure to loud noise like an explosion or very loud mike can also cause temporary hearing loss.
    Hereditary hearing loss can either be accompanied by other medical conditions (syndromic) or be independent of other medical reasons (nonsyndromic). Incidentally, approximately 70 out of 100 cases of hereditary deafness are nonsyndromic.
    Accident, injury, or other any external forces can cause physiogical damage to the ear, affecting the ability to hear. Head injuries that severely damage an inner part of the ear, or cause ruptured ear drums can progress to hearing loss. Sometimes middle ear infections due to earwax accumulation can cause temporary hearing loss.