Author: Tracy James

In this post I would like to share some thoughts about rule 3.

This is the rule that many people scratch their head over, mainly because it can be difficult to see, but also because it doesn’t come up that often (and generally only in more complex cases). Therefore, if you’re used to testing routine cases you may not have to think about rule 3 very much. That’s why it’s good to refresh your knowledge so that you don’t miss it when it does come along. Completing rule 3 means that your hearing test will be more accurate; the end result may affect your diagnosis and also your hearing aid prescription.

How does Rule 1 differ to Rule 3 in masking?

We know that Rule 3 is only needed when Rule 1 has not been carried out and that both involve air conduction masking. But why?

Masking is carried out when there is a difference of 40dB between cochleae when using headphones. When we look at Rule 1 the difference between the two cochleae are obvious:

We mask the air conduction, and find the following:

Rule 1 was carried out at all the frequencies as there was a difference of >40 dB  at all the frequencies between the 2 ears. Headphones were used and the left ear was the test ear, and the right ear was the non-test ear, to be masked.

However, the difference between the two cochleae can be hidden when the non-test ear has a conductive component. Say for example the same patient as above comes back a few weeks later with a hideous cold that has affected his right ear.

There was no need to do air conduction masking in this scenario (Rule 1 not required).

Bone conduction was carried out on the worse ear:

As the there was an air bone gap of >10dB between the air and bone conduction thresholds (Rule 2), bone conduction masking needed to be carried out at 0.5, 1, 2 and 4 kHZ. The left ear was the test ear using bone conduction, and the right ear was the non-test ear, to be masked.

Once bone conduction was completed, we could see an asymmetry once again:

In this case we could only see that the right cochlea was >40dB better than the left cochlea because bone conduction had been completed. So we went back to using headphones again and masked the air conduction, with the masking noise in the right ear (non-test ear), and retested the hearing thresholds on the left ear (test ear). This revealed the following:

Moderate to severe sensorineural hearing loss on the left. Mild conductive hearing loss on the right.

Rule 3 explained? (Some tips):

• Rule 3 is usually required because the non-test ear has a conductive component
• The asymmetry that is present between the 2 cochleae (as you would visibly see in Rule 1) is hidden until you carry out the bone conduction. That is why you only carry out Rule 3 if Rule 1 has not been carried out.
• Rule 3 is often missed because the BC that relates to the better ear (non-test ear) is recorded on the side on which the BC is placed (worse ear). Therefore you have to think to which ear the not-masked BC belongs to.
• Although you check the BC to ascertain an asymmetry, you don’t use the BC in your masking procedure – you are masking the AC thresholds only.
• At frequencies where no b-c thresholds have been measured – if there is a possibility that a-c threshold at these frequencies (including 250 Hz and 8000 Hz) are not the true thresholds, they should be masked.

If you have any questions please send an email to admin@tjaudiology.com and either myself or Louise will get back to you

Tracy James of TJ Audiology delivered a 3 day BSA certificate training course in Audiometry and Tympanometry at Medivar in Tallin, Estonia. Tallinn was fantastic, with a beautiful old town; cobbled streets, 14th Century buildings and lots of history. Estonians are also very exotic with only 1 million inhabitants. For those of you that don’t know – Estonians speak Estonian which has a lovely sing song lilt to it.

The training course was delivered to 5 employees in English and I was amazed at how those on the course (and Europeans in general) were able to use English in their day to day lives. Everyone took great assurance in having lots of practice time and as the group was small, there was lots of time to make sure that questions could be answered. Some of what we covered included anatomy and physiology, otoscopy images (possible abnormalities we may come across), contraindications, physics of sound as well as the practical procedure.

Feedback included: “Very thorough and in-depth. Informative, professional and gave consistent support and feedback to the practical assessments as well as to how we were progressing in general. Pace was perfect.”

I was pleased to have visited both Estonia and Medivar and to learn more about Estonian culture as well as Audiology Services. Medivar is a European distributor of health equipment, including Audiology equipment and supplies. I found the people I worked with there very professional and I was very well looked after. Thank you very much!

 

 

The HSE indicates there is variation in practice and standard across practitioners in Hearing Surveillance Programmes. Does your occupational health worker attend a British Society of Audiology accredited course?

Tracy James MSc

The Health and Safety Executive (2013) carried out visits and questionnaires across a range of health surveillance programmes across the UK so that current practices across teams and individuals could be evaluated. Their key findings included that there was variation in practice across practitioners and health surveillance programmes. In particular, they noted that:

 ‘….some practitioners probably did not adopt sufficient measures to exclude the effects of prior exposure to noise and background noise when the test was being conducted’

…and with regards to training competency they noted:

‘If practitioners had undergone appropriate training there is an assumption that they would be competent to undertake otoscopy, but it was found that otoscopy was not always carried out before testing’

HSE (2013). Current Practice in Health Surveillance for Noise, pp iii

The Health and Safety Executive (HSE) outlines clearly what is required with regards to a health and surveillance programme under the Guidance on Regulations ‘Controlling Noise at Work’ 2005. In Appendix 5 it reports that a training syllabus for industrial audiometricians has been prepared by the British Society of Audiology (BSA) which has accredited a number of courses. The document is available https://www.thebsa.org.uk/wp-content/uploads/2023/10/OD104-65-Surveillance-Audiometry.pdf

Why choose a BSA accredited course? In order to be accredited, the provider has submitted the course content and assessment material to experts in the field to ensure that the training is accurate and according the recommended procedures published by the BSA. It also ensures that the minimum training guidelines are fulfilled and that the trainer has a suitable background knowledge/qualifications for providing the training. A representative of the BSA will also visit the course provider during their training programme.  In order to remain accredited, course providers are required to resubmit their training material every 3 years to ensure the course is up to date.

BSA industrial audiometry courses are designed to enable occupational health workers to:

• Undertake a brief subject interview and/or administer a questionnaire regarding otological and noise history
• Perform otoscopy and pure-tone a-c threshold audiometry without masking, both in accordance with BSA recommended procedures. Audiometry may be manual or automated
• Interpret results and classify them in accordance with HSE guidelines
• Relay information to subjects and, with consent, to the employer or other person with overall responsibility for that particular hearing test program.
• Make appropriate 3^rd party referrals

BSA (2008)

Has your occupational health worker completed a BSA accredited course in industrial audiometry? When you scroll online you can see many courses that quote their course is ‘BSA approved’ or  ‘based on’ BSA guidelines or ‘follows’ BSA recommended procedures – but they’re not actually accredited! The BSA lists the accredited courses available nationally on https://www.thebsa.org.uk/wp-content/uploads/2023/10/OD104-26-V8-Accredited-Course-Providers-July-2022.pdf or you can check your course is accredited by contacting bsa@thebsa.org.uk.

A BSA accredited course may the key to enable consistency in training and competency levels across practitioners within a hearing surveillance programme. Choose your course and make sure it is accredited. The BSA (2008) recommends that the occupational health worker attends a refresher course in industrial audiometry every 3 years.

 

References

HSE (2013). Current Practice in Health Surveillance in Noise.

HSE (2005). Controlling Noise at Work. Guidance on Regulations

BSA 2008. Guidelines on the Training of Industrial Audiometricians.

Tracy James MSc is a Clinical Scientist and co-director of TJ Audiology Services along with Louise Hart, an Audiology Training Service. The next BSA accredited course in Industrial Audiometry is at PC Werth Headquarters, London