Class-leading technology to support the emergency services

Reading Time: 5 minutes
by Christopher Daniel
Published 17/08/2021

Being able to communicate effectively is essential for employees in many occupations, particularly those working in emergency services such as the police, emergency responders, and fire and rescue. The Health and Safety Executive (HSE)1 advises that all employers implement health surveillance programmes to make sure their at-risk workers are safe and effective while doing their job. 

A certain standard must be met by new recruits and employees, in order for them to perform their role sufficiently. Where a person fails to meet the minimum standard or there is a need to further assess their ability to perform a role, different tests can be used. The Home Office for National Recruitment Standards recommends that:

‘For borderline cases or when hearing in one ear is above the standard and hearing in the other ear below standard, or when hearing aids are fitted, consideration should be given to a practical test of hearing to assess functional ability, for example speech and/or phoneme comprehension.’2

These additional tests help with making appropriate decisions on whether employees can be retained in their roles, or contribute towards fair decisions on any reasonable work adjustments that could be made to enable them to do their role sufficiently.

Using pure tone audiometry

Pure tone audiometry is the most common tool used in health surveillance to understand a person’s hearing threshold. It provides a useful snapshot of a person’s hearing level which can then be tracked over time. 

Different standards are applicable depending on roles (e.g. standards defined through the HSE), or additional safety critical standards, such as PULLHEEMS H2 for police service, which is a sum of less than 84 dB at 0.5, 1 and 2 kHz and less than 123 dB at 3, 4 and 6 kHz.

The limitations of pure tone audiometry 

However, many sensorineural hearing loss issues (that is hearing loss caused by damage to the structures in your inner ear or your auditory nerve) cannot be identified through pure tone audiometry alone. 

Whilst it is a great tool for measuring hearing acuity, it has been demonstrated as a poor predicter of hearing ability in complex listening environments, which is especially important in safety critical roles. It is also not as effective in predicting hearing ability, therefore additional testing is often required.

There is a big difference in measuring hearing acuity (the ability to hear in itself), and hearing ability (what someone has actually understood). The factors that reflect the way in which we hear, understand, and identify speech, can be defined as psychoacoustic and non-psychoacoustic.

 
Psychoacoustic abilities Non-psychoacoustic abilities
Frequency selectivity Working knowledge (context)
Temporal fluctuations Experience
Loudness recruitment Age
   Situational awareness
   Working memory

 

It’s a combination of these factors that usually determines how well someone hears and understands. Within blue-light service roles, a practical assessment is often used to fully assess a person’s ability to hear, as this helps to more clearly determine their ability to do their role safely and effectively.  

Why use a practical or functional hearing test

A practical or Functional Hearing Test (FHT) measures hearing ability in a real-world scenario. For example, police officers are often exposed to a barrage of sounds happening at once from different sources and different directions. They need to be able to hear and understand a command whilst exposed to this level of noise, so an FHT would look to mimic this.

This is why police forces and other services will often use functional hearing tests in addition to pure tone audiometry to accurately determine someone’s ability to perform a role, or as part of a risk assessment. However, some practical hearing tests require a lot of operational time and expense to conduct in the right way. The challenge therefore, is that they can sometimes be deemed subjective, or unreliable (where results are not repeatable).

An alternative solution - Speech-in-Noise (SiN) test options

Instead of a practical test (or alongside it), some forces will use a Speech-in-Noise (SiN) test to assess hearing ability. There are several different tests available that analyse and assess SiN ability, including a Hearing-in-Noise Test (HINT), Quick-Speech-in-Noise (QuickSiN), Words-in-Noise (WiN), Triple Digit Test (TDT) and the Coordinate Response Measure (CRM).

They each measure the ability to recognise spoken words in various ways amongst background noise. Essentially, what we know is that, when people listen to speech they apply their existing knowledge of language, layered with their own contextual understanding of the real world alongside their previous experiences, to make predictions about what is likely to come next. So it’s important to distinguish these pre-conceptions from a real ability to hear during testing.

Benefits of the Amplivox Functional Hearing Assessment System (FHAS)

Amplivox has developed a bespoke Speech-in-Noise (SiN test) in partnership with the Civil Nuclear Constabulary and the Institute of Sound and Vibration Research (ISVR). It is a dedicated test designed especially for blue-light services which goes beyond pure tone audiometry.

The test is part of a Functional Hearing Assessment System (FHAS) which blends standard audiometric testing procedures, automated workflow management, and class-leading technology to deliver a bespoke and comprehensive hearing assessment system.

Like other SiN tests, the Amplivox version enables you to accurately assess hearing ability, but the big difference is that it takes account of the environments and challenges that police officers and other service personnel have to operate in, so consequently offers more real-world reliability and assesses results against a defined standard.

It effectively measures hearing ability whilst assessing the impact of several psychoacoustic and non-psychoacoustic factors, and has been proven as a reliable and repeatable predictor of hearing ability in complex listening environments. Not only this, our SiN test can differentiate between hearing ability levels for normal and hearing-impaired subjects, giving confidence in results.

It has also been used by various organisations to help make decisions on employees (existing and new) as to their ability to fulfil a role if their hearing does not meet the PTA standards. This has enabled organisations to protect the knowledge and talent within their business, while also ensuring the best possible candidates are hired. Some of the other benefits that the Amplivox FHAS offers:

  • It’s objective and auditable – so ideal in helping key decision making
  • It provides a potential reduction in medical referral costs
  • It can minimise absence from work due to immediate functional hearing test results
  • It offers a fully automated test and referral system which improves accuracy when recording results and issuing appropriate guidance
  • It enables employers to meet hearing acuity and ability measurements according to relevant industry standards (Pre-placement, CoP, HSE, PULHHEEMS).

For more information on our Functional Hearing Assessment System please visit our webpage, contact our customer support team on +44 (0)1865 880 846, or email.

 

References

1HSE. Health surveillance and occupational health
https://www.hse.gov.uk/health-surveillance/ 

2Gov.UK. National recruitment standards - Medical standards for police recruitment
https://www.gov.uk/government/publications/national-recruitment-standards-medical-standards-for-police-recruitment 

3The Hearing Journal. Minimum Plateau in Pure Tone Audiometry: A New Audiometric Symbol?
https://journals.lww.com/thehearingjournal/blog/OnlineFirst/pages/post.aspx?PostID=74