Survey of Noise Levels in daily teaching situations

December 2001

Background

This survey was carried out in November 2001, in response to current concerns that some staff in instrumental teaching situations may be experiencing levels of sound which exceed the permitted levels. This page is a brief summary of the survey and findings. The full report which details what instruments were tested, their results and recommendations can be downloaded here.
noise.pdf..(69Kb)

For further enquiries about this survey contact Kevin Edwards at wamc@doncaster.gov.uk 

The survey was exploratory rather than definitive, in that only a sample of staff who were likely to be affected were tested. However, the results can fairly be extrapolated to take into account staff who work in similar situations.

Sound levels where action needs to be taken

The level of sound to which a person can be exposed is based on two factors - noise level and noise duration. Combined they make up a noise dose, and two action levels have been agreed which are based on the average noise level over an eight hour working day. The 1st level is 85dB(A), the 2nd is 90dB(A). Where the exposure lasts for a shorter period the average noise level can be higher. For the purpose of this survey, a working day was taken to be 6 hours.
In addition to these two action levels, the law also states that where a person is exposed to a sound louder than 140dB - no matter how short the noise is - the exposure must be kept below 140dB, and all actions required in action level 2 apply.
The Noise at Work Regulations 1989, ISBN 0110977904 is published by The Stationery Office Limited. There is an Internet version here

How the testing was done.

An approach was made to the Association of Noise Consultants to ask for advice on the most effective way for our Service to carry out a noise level survey. As a result, two companies - Hepworth Acoustics (Sheffield) and Vibrock Limited (Heanor, Derbyshire) were asked to provide advice and quotations based on our instructions.

Two dose badges (made by Cirrus) were subsequently hired from Vibrock Limited. These record the average dose of sound to which the wearer has been exposed. These were worn in turn by several members of staff during the course of a typical teaching day. The levels recorded during each day were read into a badge reader, and a printout of readings taken was supplied by Vibrock at the end of the hire period.

Brass, wind, percussion, recorder and electric guitar lessons and ensembles were tested. In addition, two wind band rehearsals were tested. One over a two hour period, and one over a four hour period.

The actual length of time of each test is not critical - a longer test period might produce a more accurate average reading where the levels of a person's sound exposure varies greatly during the day ie. sometimes they have "quiet" periods. For the purpose of this survey, it is fair to assume that a teacher is doing similar work throughout the rest of the teaching day. The average sound level results can be compared with the action levels by using a formula to produce an LEP.d based on the length of exposure. In most cases this was 6 hours, but some ensembles which run for between one and four hours were also tested.

Results

Most staff tested exceeded noise levels above the 1st action level. It is fair to assume that all brass, woodwind and percussion teachers are working in environments which, on some days at least, will exceed the 1st action level.
It is therefore a requirement of the Noise at Work Regulations that these staff are

provided with adequate information, instruction and training about risks of damage to hearing. Ear protection should be made available to these staff if they ask for it.

Some staff exceeded the 2nd action level and/or the peak level.

It is therefore a requirement of the Noise at Work Regulations that these staff are

provided with adequate information, instruction and training about risks of damage to hearing and, as far as is practicable, they should also have their exposure to these noise levels reduced by means other than ear protection.
This could mean -
1) Reducing the length of time of exposure (Electric guitar group would need to be reduced to 1 hr 30 mins - Wind band exposure to 3 hr 30 mins )
2) Finding a better teaching environment
3) Not playing along with pupils (own sound adds most to the daily dose)

In addition, ear protection should be made available to these staff and DMS has a responsibility to make sure it is worn by all exposed.
Ear protectors should be maintained and repaired by DMS.

As a result of this recent survey, Doncaster Music Service will be providing either ER20 or "Quiet Please" ear plugs for staff at risk. These cost around £10 per pair, and are re-usable. Their lifespan is thought to be about one year if properly maintained.
Staff have also been made aware of the ER15 plugs, which are custom made (but around £150 per pair). Their lifespan is around five years.

The formula used to calculate the LEP.d over a given time period is -

LEP.d = 10 x LOG (T divided by 8) + L

where T is the length of the working day (or exposure time in the case of ensembles) in hours, and L is the average level of noise (or Leq) expressed in dB(A) over the tested period.

The formula used to calculate the length of time a person can be exposed to a particular noise level and stay below the 90dB(A) action level is -

T = 8 x 10^((90 - L) divided by10)

where T is the time allowed in hours (the result) and L is the average level of noise (or Leq) expressed in dB(A)over the tested period.