There are 3 parts in the auditory system, namely, the outer ear, middle ear and inner ear. The outer ear includes pinna and outer ear canal. The middle ear includes the tympanic membrane and 3 small ossicles. The inner ear includes the cochlear that connects to the auditory cortex via the auditory nerve. The pathway of sound transmission is as follows:
Transmission of sound
The severity of a hearing impairment is categorized according to the softest intensity of sound a person can perceive. Person with normal hearing can hear sounds at or below 25 dB HL. Hearing level above this range is considered as hearing loss. The degree of hearing loss is universally classified into 5 categories: mild, moderate, moderately-severe, severe and profound.
There are 3 types of hearing loss, including conductive hearing loss, sensorineural hearing loss and mixed hearing loss.
Conductive hearing loss is caused by abnormality of the outer or middle ear, which affects the transmission of sound to the inner ear. Some common causes include infection in the middle ear, perforated ear drum, earwax occlusion and otoscelerosis, etc.
Sensorineural hearing loss is caused by damaged hair cells or hearing nerve, which results in a loss of loudness and clarity of speech. Sensorineural hearing loss can result from aging, virus infection, excessive noise exposure, ototoxicity etc.
Mixed hearing loss is caused by the combination of damage to the outer/middle ear and the inner ear. Typically, sound waves cannot pass through the outer ear/middle ear efficiently 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.
Hearing impairment can bring emotional, social and economic loss to individuals. Some common ways to protect your hearing include:
Never use cotton bud or ear pick to remove earwax yourself to avoid damaging your eardrum or pushing earwax inside your ear.
Follow the 60-60 rule when using personal audio devices (i.e. <60% of maximum volume of the device for <60 mins).
Wear earplugs to reduce noise exposure in noisy places such as concert and stadium.
Use swimming earplugs for swimming to maintain ear hygiene.
Seek help from hearing professional in case tinnitus/difficulty in hearing is noted.
Get regular hearing check-ups.
Hearing loss is often difficult to notice at its onset. If you have noted any difficulty in watching telephone, telephone usage or daily communication, you are recommended to have a hearing test. After comprehensive audiological assessment, your audiologist should be able to determine your degree and nature of hearing loss, and recommend choices of hearing aids and/or assistive listening devices to suit your listening needs.
It is not recommended to purchase non-prescribed hearing aid(s) without any hearing test. A non-prescribed hearing aid may not provide optimal amplification for you, or it may provide too much amplification to damage your residual hearing. Hearing aids should be adjusted according to individual degree of hearing loss and listening needs. Please consult your audiologist for any advice on hearing aid.
Apart from the speaker’s voice, hearing aid(s) amplifies environmental sounds as well. As human brain needs time for adaptation to amplified sounds, it is recommended that hearing aid users get used to listening in typical quiet environment first before using the hearing aid in noisy listening environment. Modern digital hearing aid technologies also facilitate listening in noisy environment through directional microphone and automatic noise reduction to enhance speech understanding in different situations.
With proper care and maintenance, your hearing aid(s) should last for at least 3 to 5 years or above.
The price depends on the style, technology level, brand and also features of hearing aid(s) you choose. Remember, the price of hearing aid also includes follow-up service, adjustment and maintenance fee. Your hearing professional will recommend a hearing product that suits your lifestyle and communication need.
