Miniature microphones and their use

ISVR Consulting uses two main methods of measuring noise levels at the ear and assessing noise exposures under headsets, helmets, earpieces and earphones.  One method uses an acoustic manikin or Head and Torso Simulator which has the dimensions and acoustical properties of a median adult.  The other uses miniature microphones to measure the sound at the ears of human listeneners. This technique is known as the ‘MIRE’, or Microphone In Real Ear, method.  Whether the manikin method or the MIRE method is used depends on the application, as each has advantages and disadvantages.   At ISVR Consulting we use both methods.

  

Examples of the use of miniature microphones and the MIRE method

Miniature microphones

Two types of miniature microphone with a 5 pence coin

Yamaha Rhino in police livery

A Yamaha Rhino off-road vehicle

NPAS Helicopter

A National Police Air Service EC135 helicopter

The MIRE method is particularly useful when a real person has to be present, to ride a motorcycle, for example. At ISVR Consulting we regularly use two types of miniature microphone, as shown in the photograph, and the choice depends on the application. 

We have used miniature microphones to measure the noise reaching real ears for various applications:

 

Other uses of miniature microphones

We have also used miniature microphones to measure and record noise levels in situations where their small size and unobtrusiveness is an advantage, and where normal microphones and preamplifiers are not convenient or practicable.

We used miniature microphones, for example, to measure the noise levels during aircraft cabin evacuation trials, and to measure the noise levels produced by aircraft cabin watersprays. (Published as D M Bottomley1, H C Muir1 and M C Lower2, 1993;  Aircraft evacuations: the effect of a cabin water spray system upon evacuation rates and behaviour.  CAA Paper 93008.  Civil Aviation Authority, London.  ISBN 0 86039 547 2.  1Cranfield University, 2ISVR Consulting, University of Southampton.)