Hearing Care

Understand Ear and Sound

Human beings have five senses. Every sense receptor is a complex piece of bioengineering. This natural marvel does not have a manmade or mechanical counterpart. It receives and converts sounds of nature, music, conversations with family and friends, etc. into legible sounds that we can relate to.

Additionally, human ears act as a natural warning system. It is capable of identifying oncoming traffic, processing a possible break-in, alerting when there are other possible dangers, etc. Thus, hearing is a critical human sense and we must not wait until we experience hearing loss in order to remind us about its importance.

Life is not worth living without the sounds and voices that matter!

Ear

The human ear has three parts:

The outer ear (pinna, ear canal and eardrum)
The middle ear (the ossicular chain)
The inner ear (semicircular canal cochlea)

The outer ear collects the sound waves and transmits them towards the eardrum, or tympanum. The tympanum vibrates and these vibrations are carried inside and amplified further by the ossicular chain. Further amplification takes place in the inner ear and the sensations are taken to the brain for analysis.

Sound

Sound waves are like ripples created on a pond’s surface when it is disturbed by a stone. Sound waves, like ripples, move out as differences occur in air pressure (compressed air and rarefied air). When these fluctuations hit the eardrum, they manifest as sound.

Sound travels as waves of pressure through air at a speed of 740 miles (approx. 1184 km) per hour. There are two features of sound that we can measure — pitch and intensity.

Pitch, also known as frequency, is a measure of how rapidly the waves change from above to below the ambient pressure. In other words, it is a measure of how many crests pass a point in a second. The greater the number, the higher is the pitch.

Intensity (loudness or amplitude) is a measure of how far the waves are above or below the ambient pressure. The greater the amplitude, the louder is the sound. Pressure levels of sound are measured as decibels (dB).

Hearing Loss Overview

The human ear is capable of hearing sound from 0 dBhL (faintest sound perceivable by a normal adult) to about 140 dBhL (the noise of a jet engine within 250 yards).

Hearing disability can be congenital (from birth) or acquired (through a loud work environment). It can be managed through mechanical hearing devices or surgical interventions.

While a hearing disability is looked upon as a social stigma, it must be discussed and acted upon. Because, many times, acquired hearing disabilities can get worse with time. As hearing abilities get worse, people start experiencing problems with everyday life, like driving in the traffic, daily communication, etc. This can cause depression, frustration and other emotional problems. Hence, timely intervention in hearing impairment is very important.

Hearing impairment can be classified as follows:

Normal (0 to 20 dBhL)
Mild (cannot hear below 40 dBhL)
Moderate (cannot hear below 60 dBhL)
Moderately severe (cannot hear below 75 dBhL)
Severe (cannot hear below 75 – 90 dBhL)
Profound (cannot hear 90+ dBhL)

There Are Three Main Types Of Hearing Loss

Conductive Hearing Loss

This occurs when there is a problem with the outer or middle ear.

Causes Conductive Hearing Loss

Malformation of outer and middle ear structures
Could be hereditary or can occur during an accident
Accumulation of fluid in the ear canal
Ear infections like otitis media
Perforated eardrum(s)
Allergies
Benign tumors
Impacted earwax obstructing passage of sound
Infection of the ear canal
Presence of foreign bodies

Sensorineural Hearing Loss

Sensorineural hearing loss can occur due to damage to the nerves in the inner ear or due to damage to the cochlea. It cannot be reversed or treated.Noise induced hearing loss is caused due to exposure to high intensity noise which causes permanent nerve damage.

CAUSES Sensorineural Hearing Loss

Before or during birth
Lack of oxygen at the time of birth
Heredity
Infections such as rubella, herpes, toxoplasmosis, syphilis, cytomegalovirus (CMV)
Later onset
Bacterial meningitis
Drug-induced ototoxicity
Intense noise
Physical damage to the head or ear