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Diary of an Audiometric Screener

Anitech Consulting launched its audiometric testing services in Queensland earlier this year. Urban Turf Solutions had their employees’ hearing tested by the new Audiometric Testing Queensland (ATQ)in April 2017. From then on Renita Premanand, our new audiometric assessor has been busy assessing employees’ hearing abilities of various companies in Queensland. She has travelled from Oakey in the south to Normanton in North Queensland, including Bowen, Tully, Mareeba, Innisfail.

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“Driving from Brisbane to Normanton was very adventurous and interesting. We drove for 3 days through the coastline enjoying the varying landscape”, said Renita. Normanton was a very different experience – a tiny town in the Gulf of Carpentaria where people were very laid back, enjoying fishing and hunting. Audiometric Testing Queensland provided audiometric services to the Carpentaria Shire Council employees, most of whom work in remote camps. Ninety people were tested for hearing abilities there. “We share the test results with individual employees and re-iterate the significance of wearing hearing protection appropriately”.

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Audiometric Testing: Did You Hear That?

Depending on your local health and safety regulatory jurisdiction, audiometric testing will be required once decibels reach a specific action level.  Audiometric testing is part of an organizations overall hearing conservation program that is completed annually, at a minimum.

What is an audiometric test? It is a test to determine a workers’ hearing levels with the help of an audiometer.  Simply put, it is a test to determine how well you can hear, or not hear?  The test will validate if a workers’ hearing is being compromised or not.

Audiometric Testing

Audiometric testing identifies…

–  Progressive noise-induced hearing losses before they become an impairment

–  Temporary losses before they become permanent, providing time for remedial steps

The audiogram is a graphical display of the hearing test. The audiogram (a graph or table of an audiometric test results) will be available to the worker and by the employer.

The two main components that are graphed are frequency and intensity. These results are displayed for each ear. When you had your hearing tested, the audiologist was determining the softest sound you could hear at each specific frequency.  Without regular audiometric testing you may not know your hearing is being compromised until it is too late!

Below are the 4 steps needed to ensure that noise, as an occupational hazard, is monitored and operational controls are in place to minimize or eliminate such noise.

  1. Measure your workplace sound levels to determine who needs to be tested.
  2. Review engineering, administrative and personal protective measures to limit worker noise exposure.
  3. Schedule mobile testing, and provide training for employees affected by noise.
  4. Understand local jurisdictional and other regulatory bodies requirements for noise hazards and maintain compliance.

PRE TEST EXAMINATION

The examiner will ask you questions as part of the evaluation…

–  Ear, nose, & throat problems such as colds, infections, and congestion?

–  Noisy hobbies or activities?

–  Time since exposure to loud noise?

The examiner may also visually check your outer ear canal with an otoscope for…

–   Ear infections

–   Excessive earwax

–   Obstructions in the ear canal

AUDIOMETRIC TEST

  • You will sit in a quiet booth and be equipped with a headset and a signal switch
  • You will hear tones of varying level and frequency
  • You will be instructed to depress the signal switch to indicate a tone was heard
  • Be honest; don’t try to anticipate or intentionally miss a tone, or the test will be invalid

AUDIOMETRIC TEST RESULTS

Your audiogram will be used to indicate hearing change.

–    A Temporary Threshold Shift (TTS)

  • A temporary reduction in hearing due to fatigue of the ear caused by noise exposure
  • Temporary hearing loss – indicates the potential for permanent loss

–    A Standard Threshold Shift (STS)

  • A change in hearing sensitivity for the worse relative to the baseline audiogram
  • An average change of 10 dB or more at 2, 3, and 4 kHz in either ear

The benefits of participating in an audiometric test include preventing adverse effects such as tinnitus – ringing in the ears; temporary hearing loss or permanent hearing loss.   Noise is an occupational hazard that can be identified, controlled and measured.  Audiometric testing is a validation of how effective an employer’s hearing conservation program is, or is not.

 

Audiometric Testing: The Various Types of Tests

There are multiple types of audiometric testing to validate if a workers’ hearing health has been jeopardized due to working around noise.  Some of these tests are briefly described in this article.

Audiometric Testing

  1. Pure Tone Audiometry

Pure tone audiometry (PTA) tests are the most common type of test used for evaluation of occupational noise.  During PTA, a machine called an audiometer is used to produce sounds at various volumes and frequencies (pitches). You listen to the sounds through headphones and respond when you hear them by pressing a button.

  1. Speech Perception

The speech perception test, also sometimes known as a speech discrimination test or speech audiometry, involves testing your ability to hear words without using any visual information. The words may be played through headphones or a speaker, or spoken by the tester.  Sometimes, you are asked to listen to words while there is a controlled level of background noise.

  1. Tympanometry

During tympanometry, a small plastic bung seals your ear and the machine gently changes the pressure in your ear canal. The purpose of a Tympanometry test is that it measures the movement of the eardrum and the pressure behind the eardrum to determine if any fluid is behind the eardrum.  It will also indicate if the Eustachian tube is working properly or not normally.

  1. Whispered voice test

The whispered voice test is a very simple hearing test. It involves the tester blocking one of your ears and testing your hearing by whispering words at varying volumes. You will be asked to repeat the words out loud as you hear them.

  1. Tuning fork test

A tuning fork test produces sound waves at a fixed pitch when it is gently tapped and can be used to test different aspects of your hearing.  The tester will tap the tuning fork on their elbow or knee to make it vibrate before holding it at various different locations around your head.

The purpose of the tuning fork test is to help determine if you have conductive hearing loss, or sensori-neural hearing loss.

  1. Bone conduction test

A bone conduction test is often carried out as part of a routine pure tone audiometry (PTA) test in adults.  A bone conduction test involves placing a vibrating probe against the mastoid bone behind the ear. It tests how well sounds transmitted through the bone are heard.  The bone conduction test is a far more sophisticated version of the tuning fork test, and when used together with PTA, it can help determine whether hearing loss comes from the outer and middle ear, the inner ear, or both.

  1. Hearing Test Results – The Audiogram

The results of some hearing tests are plotted on a graph called an audiogram.  An audiogram is used to record the measurements of different volumes and frequencies (pitches) of sounds you are able to hear.  As well as showing a comparison between your ears, an audiogram can also help to determine what type of hearing loss you have, if any.  The type of hearing loss you have is important because it determines what help or treatment is most suitable for you.

Audiometric Testing: The Audiogram

If you have experienced an audiometric test, chances are you have seen and been told the results of your test via a graph.    But did you really understand the information?  Was the information not communicated well to you?  This article will provide, in general terms, an explanation of what an audiogram represents.

The audiogram is a chart of hearing sensitivity with frequency charted on the X- axis and intensity on the Y-axis. Intensity is the level of sound power measured in decibels; loudness is the perceptual correlate of intensity.  Below is an example of an audiogram:

Audiometric Testing

Most common way to measure hearing sensitivity is to measure pure-tone (sinusoid) thresholds.

Below is an example of an audiogram.  The red line is the right ear of this particular worker.  This audiogram represents Pure Tone Average (PTA).  The average thresholds at 500, 1000, 2000 Hz are the frequencies most important for speech understanding .  In this particular scenario, the PTA of the left ear was 93 dB compared to 50 dB of the right ear.

Audiometric Testing

The magnitude of hearing loss is defined as follows:

  • Normal hearing loss:  0 -15 dB.  Some interpretations have normal hearing loss ranging up to 25 dB
  • Slight hearing loss:  16-25 dB
  • Mild hearing loss:  26-40 dB
  • Moderate hearing loss:  41-55 dB
  • Moderately-Severe hearing loss:  56-70 dB
  • Severe hearing loss:  71-90 dB
  • Profound hearing loss:  91+dB

There are 3 types of Hearing Loss to understand when reviewing your audiogram:

  1. Conductive is abnormality of the outer or middle ear.  Usually temporary and medically treatable.The Impaired Ear (Conductive Loss) occurs when there is a disruption of the transmission of sound (Ex: fluid in the middle ear).  Typically, this loss occurs in the outer or middle ear and many times is a temporary loss that can be treated medically.
  2. Sensorineural is damage to the inner ear or nerves of hearing.  Usually permanent. The Impaired Ear (Sensorineural Loss) occurs for many reasons.  Starting from age 20, the hair cells slowly begin to deteriorate.  Hair cells can also be damaged from loud noises, medicine, head trauma or other causes.  This type of hearing loss are mostly due to natural loss of hair cells.
  3. Mixed include both Conductive and Sensorineural.

 

Besides just understanding the audiogram, it is important to remember that audiometry is a subjective test requiring a verbal or physical response and therefore can be subjective.  Audiometry tests all parts of the ear, the entire auditory system.  The most common type of audiometry, that you and I are familiar with is the Pure Tone audiometry test.  This type of test includes headphone, insert earphone or speaker.  A machine called an audiometer is used to produce sounds at various volumes and frequencies (pitches).You listen to the sounds through headphones and respond when you hear them by pressing a button.This test evaluates the sensitivity of the entire hearing organ.  The audiologist presents single frequency (“pure”) tones produced by a calibrated audiometer. The softest sounds heard by the subject at each pitch are recorded as the thresholds and are compared to normative values.  This recorded comparison is found on the audiogram, a graph that you now understand what it means and how it benefits you by knowing what type, if any hearing loss you may have.  The type of hearing loss you have is important because it determines what help or treatment is most suitable for you.

Audiometric Testing: Benefits of Testing

When occupational noise hazards exceed the exposure standard indicated in occupational health and safety requirements, workers are required to use Personal Hearing Protection (PHP) to reduce the risk of hearing loss. These workers are also required to participate in audiometric testing to ensure the effectiveness of the hearing protection measures.

This audiometric testing may be required annually or every two years, once again depending on your local occupational safety jurisdictional requirements. This article discusses the benefits of audiometric testing and defines exactly what audiometric testing involves.

Audiometric Testing

WHAT IS AUDIOMETRIC TESTING?

Audiometric testing determines workers’ hearing levels with the help of a tool called an audiometer. It is a very simple procedure that involves an employee receiving a series of different tones; for each tone, the participant can respond indicating that they heard the tone.

The tones are presented at different sound levels and checked multiple times to identify the lowest level at which a person can hear. This is called the “threshold limit,” and is compared to a “baseline test.” Audiometric testing is conducted for different frequencies, and both the left and right ears. As a result, it provides a way to monitor the sharpness and acuity of an employee’s hearing over time.

In particular, audiometric testing identifies:

(1) Progressive noise-induced hearing loss before it becomes an impairment.

(2) Temporary loss before it becomes permanent, providing time to implement remedial steps.

ABOUT THE AUDIOMETRIC TEST ENVIRONMENT

To effectively conduct an audiometric test, the test environment must be controlled. In particular, the optimal test environment must be quiet and free of distractions. There should be no distracting activity outside the test room that the listener can see or hear. The listener needs to focus their attention on the test and not any activity surrounding them. For example, while audible speech would not mask the test tones, it would distract the listener.

While there is no such thing as a “soundproof” test room – i.e., a room which no outside sound can penetrate – it is important that rooms are designed to reduce outside noise to the point where it won’t mask the test signals, and it is just as important to not have unnecessary noise-generating activities in the area of the test room.

BENEFITS OF AUDIOMETRIC TESTING

Regularly scheduled audiometric testing identifies people who are at risk of significant hearing loss by identifying changes in their hearing threshold over time. Employers can then implement appropriate treatment plans, like providing a higher class of hearing protection, ensuring that the employee uses hearing protection correctly, and reducing the noise in particular locations.

Audiometric testing is best conducted at least a few hours into an employee’s shift to identify any Temporary Threshold Shift (TTS). Temporary Threshold Shifts can show that the Personal Hearing Protection and noise reduction strategies are not working effectively and that immediate corrective action is required.

Typical hearing loss as a result of Noise Induced Hearing Loss (NIHL) often occurs at the 3K, 4K & 6K frequencies where a V shape notch is observed when viewed on the audiometric graph, known as an audiogram.

Audiometric testing may also assist in identifying the need for diagnosis of potential medical problems, distinct from workplace hearing loss, that affect a person’s ability to hear.