Pure tone audiometry (PTA) is used to establish your hearing thresholds. The frequencies range tested is 125Hz – 8kHz. These are important frequencies since speech sounds in every day conversation fall into this range. Your audiometric results are plotted on an audiogram chart [see diagram below] that enables us to objectively measure your hearing thresholds against normal hearing. The test procedure determines the type and degree of hearing loss and provides a basis for selecting the most appropriate hearing aid to suit the loss.
Audiogram reflecting speech sounds in relation to frequency and intensity
Types of Hearing Loss
The test battery used in diagnostic audiometry helps to identify the type and degree of loss.
Conductive – A conductive hearing loss is a fault in the mechanical transportation of sound from the entrance of the ear, through the middle ear, to the entrance of the cochlear [inner ear].
Sensorineural – A sensorineural hearing loss is a permanent hearing loss affecting the inner ear. The most common sensorineural hearing loss is presbycusis [age related hearing loss].
Mixed – A mixed hearing loss is a combination of conductive and sensorineural element.
Auditory Pathway – Outer, Middle & Inner Ear
Once your hearing thresholds have been established, speech tests are carried out to determine the impact of your hearing loss on speech discrimination in more challenging listening environments. In everyday life we face complex listening environments and the purpose of speech testing is to assess the impact of background noise on your ability to hear.
Speech-in-noise testing helps us to establish a signal-to-noise ratio [the point at which background noise starts to mask clarity of conversation]. This information is crucial to hearing aid selection and it forms an important part of your diagnostic assessment. Once we have completed the test battery, the results will be used to select digital circuitry that matches your unique requirements.
We will then be in the best position to offer you our best advice on a hearing aid trial. Other important considerations for appropriate hearing aid selection will be:
- Your lifestyle