Within the occupational health industry there are some common misconceptions surrounding industrial screening programmes with regards to the ways in which safe and best practices should be adhered to.
How ambient noise levels can impact results
Ambient background noise can have a significant effect on audiometric results, so it is important that ambient noise levels remain low to ensure they do not elevate threshold outcomes. Consequently, the main concern for occupational health hearing care professionals is ensuring that any results obtained from industrial screening programmes are not affected by ambient noise levels. Below we share some considerations to help you achieve accurate audiological recordings in-line with current regulations.
Prior to testing
When setting up an audiological testing environment, standard background noise levels need to be taken into consideration, with testing environments meeting ambient condition BS EN 26189 standards.
It is usually acceptable to carry out hearing tests where the background noise level is no more than 30 dBA. If levels are a little above this, noise-reducing headphones can provide some help, but if ambient noise levels are too much above 30 dBA, this is likely to provide inaccurate and unrepeatable results.
In industry, ambient noise levels are usually met by using a sound-attenuating booth. Depending on the background noise, different types of audiology booths or a combination of an audiology booth and noise-reducing headphones can enable you to achieve the required levels of background noise.
Acceptable ambient noise levels
The table below highlights the maximum ambient background noise levels that are acceptable when used with the appropriate equipment. It is also important to be aware of changes that can happen over time in the surrounding test environment, so it is useful to carry out an in-situ acoustic check and validate the booth performance on a regular basis, such as bi-annually.
| Frequency (Hz) |
Noise level (dB) |
With typical noise
(including headset) |
With typical noise
(booth attenuation) |
| 125 |
43 |
52 |
77 |
| 250 |
28 |
41 |
74 |
| 500 |
9 |
33 |
80 |
| 1k |
7 |
37 |
88 |
| 2k |
6 |
45 |
96 |
| 4k |
7 |
51 |
107 |
| 8k |
10 |
45 |
106 |
When using an audiology booth or any other audiological testing facility, try to make sure it is placed as far away as possible from sources of noise, such as toilets, foot traffic, or air conditioning. Also remember that audiology booths are only able to reduce sound by a limited amount so cannot guarantee a complete soundproof environment.
During testing
All tests should be conducted by adequately trained healthcare professionals who understand the potential impact of any background noise on the results. The use of sound level meters can be a helpful additional tool in monitoring background levels, although are not a legal requirement.
Monitoring
During the testing process it is essential to monitor the situation based on your surroundings, complete a risk assessment of the environment and monitor any changes that occur whilst the testing is being performed, as these could impact results. Equipment should be checked on a daily basis and calibrated on an annual basis. It is also recommended to ensure that staff and operators are appropriately trained.
Training
It is important for any healthcare professional to have sufficient information, instruction, and training to ensure they operate to industry standards and within legal frameworks as part of a Health Surveillance programme. For example, a professional performing audiological testing should be acutely aware of the impact that distracting background noises can have, and be able to clearly identify peculiarities or disparities in test results.
Audiology equipment
There is an array of audiology equipment and accessories required to perform successful hearing tests whilst minimising the impact of background noise.
Different types of noise reducing audiology booths are available depending on the ambient environment. Amplivox provides IAC acoustics 250 and 350 audiology booths that allow for accurate, safe and reliable hearing test assessments through the attenuation of background sound. They comply with the standard ISO 8253-1 for audiometric test methods, ensuring you get the best possible testing results.
Each booth is also equipped with a silent ventilation system, maintenance-free LED lighting, and a large double-glazed acoustic window to ensure the patient remains comfortable and at ease whilst the audiometric hearing test is being performed.
As well as this, we offer ambient noise checks for all audiology booth brands, which we recommend be undertaken bi-annually to ensure optimal test accuracy and performance.
We also provide Audiocups (noise-reducing enclosures) which have been designed to ensure accurate pure tone screening audiometry testing, especially in conditions where ambient noise can become too high for unshielded earphones.
Our Audiocups are the perfect accompaniment to a standard air conduction headset such as the RadioEar DD45, Telephonics TDH39 and TDH49 transducers, and they are easily retrofitted in the field without the need for recalibrating your audiometer.
For more information on our audiology booths please visit our audiology booths webpage, contact our customer support team on +44 (0)1865 880 846, or email.
Resources
Legislation.gov.uk. The Control of Noise at Work Regulations 2005. Accessible at:
http://www.thebsa.org.uk/wp-content/uploads/2012/11/Industrial-Audiometry-1.pdf