Introduction: Occupational Noise Induced Hearing Loss – It is the hearing loss that is a function of continuous or intermittent noise exposure and duration, and which usually develops slowly over several years.

Did you know?

  • About 30 million workers are exposed to hazardous noise on the job.
  • Noise induced hearing loss is the most common occupation hazard
  • Hearing loss from noise is gradual and painless, you can have disablity before you notice it.
  • It is 100% preventable

Why has this problem became so widespread?

  • Unfortunately, the effects of noise are often underestimated because the damage takes place so gradually, loud noises have become so common in our culture, and (although traumatising to the parts of the body responsible for hearing) there are no externally visible physical changes like bleeding.
  • As a result, people have traditionally not appreciated the serious impact of NIHL on their daily living until they are frustrated by a permanent communication problem or ongoing ringing in their ears (tinnitus).

Effects of Noise

It can cause two kinds of health effects:–

  1. Auditory Effects
  2. Non – auditory effects

Auditory effects :

  • Acoustic Trauma – Sudden hearing damage caused by short burst of extremely loud noise.
  • Tinnitus – Ringing or buzzing in the ear
  • Temporary Hearing Loss – Also known as temporary threshold shift (TTS) which occurs immediately after exposure to a high level of noise. There is a gradual recovery when the affected person spends time in a quiet place. Complete recovery may take several hours.
  • Permanent Hearing Loss – Also known as permanent threshold shift (PTS), progresses constantly as noise exposure continues month after month and year after year. The hearing impairment is noticeable only when it is substantial enough to interfere with routine activities. At this stage, a permanent and irreversible hearing damage has occurred. Noise induced hearing damage cannot be cured by medical treatment and worsens as noise exposure continues.
  • When noise exposure stops, the person does not regain the lost hearing sensitivity. As the employee ages, hearing may worsen as “age related hearing loss” adds to the existing noise induced hearing loss.

Non – Auditory Effects:

  • Anxiety
  • Irritability
  • Sleep disturbance
  • Decreased efficiency & productivity
  • Cardiovascular diseases

Factors Affecting Hearing Loss:

  • Noise Intensity and sound pressure
  • Frequency or pitch of sound
  • Length of daily exposure
  • Duration of exposure in years
  • Individual susceptibility
  • Other factors (disease, genetics lifestyle, age,etc.)

Acoustic Shock – It is the term for the condition which can arise after being exposed to unexpected loud sounds via telephones.

  • Employees at call centres who work with headsets on are particularly at risk.
  • Sound which can stem from feedback oscillation, fax tones, which are all high pitched tones (HPT)
  • It is typically employees in call centres who are at risk of experiencing acoustic shock since they are often exposed to these sounds during their workday and sit with headsets on most of the day .
  • Even just listening to the callers at a high level can contribute to the risk of acoustic shock.


Symptoms of Acoustic Shock

  • Headache
  • Tinnitus
  • Ear pain
  • Anxiety
  • Hypersensitivity
  • Fatigue

Purpose of Audiometric Test (Hearing Testing):

  • For a baseline audiogram for a new employee. The testing is repeated every year after that and compared to the baseline test results.
  • Most of us develop a mild hearing loss as we age, especially in the higher frequencies.
  • A severe or significant hearing loss at a younger age may mean you have had excessive noise exposure
  • Audiometric testing done yearly can detect early stages of hearing loss.

How are call centre workers exposed to noise?

Most contact centres operate as an open office type environment exposing workers to noise from a number of different sources, including:

  • ringing phones
  • voices of other workers
  • office equipment
  • customers

A background noise level greater than 60 dB(A) could cause the call handler to turn up the volume on the headset to hear over the noise. This practice may increase the risk of acoustic shock occurring as well as noise induced hearing loss in the long term if acoustic shock protection devices are not attached to headsets.

Ways to minimise the risks from background noise include:

  • use sound absorbent materials and partitions of a suitable height in the design of contact centre work stations and breakout areas
  • ensure office equipment such as printers and photocopiers are separated from the immediate work area
  • identify and remove faulty telephone lines and headsets
  • hold team meetings and briefings outside the immediate work area
  • encourage workers to not speak loudly or to hold conversations near call handlers, particularly during shift changeover
  • train call handlers to control voice levels.

What is an acoustic incident?

Contact centre workers may experience acoustic incidents such as a sudden loud shriek or piercing tone through their headsets. This can lead to an acute startle response and/or pain in the ear. Rarely some operators experience ongoing symptoms. This is more common where workers have high levels of stress.


How to protect workers against excessive noise

A person’s hearing can become temporarily or permanently impaired if their unprotected ear is exposed to excessive noise. Specific regulations about noise exist to protect workers from the risk of exposure to excessive noise.

How to test for hearing damage

Audiometric testing may be used to monitor a person’s level of hearing. To help establish whether hearing damage has occurred, audiometric testing should be undertaken at the commencement of employment to identify the baseline hearing threshold of contact centre operators. The audiometric testing process should be repeated and compared to the baseline after a person has experienced an acoustic shock incident to determine if the person has suffered any hearing damage.

More information about managing exposure to noise, noise-control strategies, ways to minimize acoustic incident and headset hygiene can be provided by the Audiologist from our Hospital.


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