• Audiometry is a painless, non-invasive hearing test that measures a persons ability to measure different sounds, pitches or frequencies
• Subjective, accuracy is dependent on the response of the patient

Performing audiometry

• Audiometry is carried out in soundproof rooms and performed using calibrated audiometers
• The aim of audiometry is to find the hearing threshold, classed as:
  • The questest sound that an individual can hear across a range of different frequencies
  • If the subject responds to a tone 50% of the time it is a statistical probability that that is their threshold

Pure tones

• Simplest of all sounds, involving a single specific frequency
• Described by frequency, amplitude (in decibels), phase and duration
• Pure tone audiometry provides information about the type of hearing loss
• Warble tones can be used in patients with tinnitus as can be difficult to distinguish between the tone and the tinnitus
• Warble tones can also be used for children <5

Audiometers

• Calibrated to measure air conduction thresholds between 125-8000Hz and bone conduction thresholds between 250-6000Hz
• Calibrated to measure air conduction thresholds of 120dB and bone conduction maximum intensity of about 70 dB maximum
  • Bone conductors produce distortions above this level

Other equipment

• 3 main transducers are used to present tones - headphones, insert headphones, bone conductor
• Equipment for responses - usually response buttons in adults, other options for paediatrics e.g. coins in a piggybank

Threshold assessments

• Both air and bone conduction thresholds are required to indicate the type of hearing loss

Air conduction thresholds