By Ms Elshi Jenifur, Audiologist & Speech Pathologist, Trichy
Noise Induced Hearing Loss (NIHL) refers to the damage of auditory sensory hair cells due to repeated or sudden exposure to loud noise. NIHL stands as the second most common cause of Sensorineural Hearing Loss.
Stages of NIHL
- A sound/noise above 70 dB entering the ears causes damage to the Outer Hair Cells (OHCs) in the inner ear, which in turn results in Temporary Threshold Shift (TTS).
- On continuous noise exposure, TTS becomes Permanent Threshold Shift (PTS), which is called as Permanent Noise Induced Hearing Loss, affecting the high frequency regions of the Cochlea.
Symptoms of NIHL
- Tinnitus – Ringing sensation in the ears
- Difficulty in hearing high frequency sounds (/f/, /s/, /th/)
- Difficulty in understanding speech in noise
Risk Factors of NIHL
- Industrial noise (> 85 dBA)
- Impact noise (drilling sounds, construction jackhammer sounds)
- Impulsive noise (gunshots, explosives, horns, aircraft flyovers)
- Recreational noise (concerts, disco)
- Personal devices (MP3 players at high volumes)
Precautions to Prevent NIHL
- Wearing ear protection devices (ear plugs, ear muffs) during occupational noise exposure
- Avoid/limit exposure to excessively loud sounds
- Taking breaks from the noise
- Turning down the volume on personal devices such as headphones
- Getting tested once a year by an audiologist
