Development Of Software-based Continuous Sweep-frequency Audiometry

Abstract

At current stages of clinical practise, the assessment of noise induced hearing loss (NIHL) in New Zealand includes an evaluation of hearing which is tested at a series of octave frequencies in conjunction with a detailed history. The 4 kHz notch has been fairly established as representing damage due to noise exposure. However this representation provides a limited overview of the status of hearing as conventional audiometry only tests the octave frequency range. This study investigates the utility of a different type of audiometric technique known as continuous audiometry which employs a sweeping signal across the frequency range being assessed. The design and development of a sweep frequency program using the programming platform Labview was employed to create a simple yet efficient means of assessing hearing. The design and development of the program drew on a range of fundamental programming principles and aspects of audiological testing protocols to produce a functional program capable of generating iso level sweep signals across a defined range of frequencies over a specified duration of time. In order to test the utility of the program and its feasibility in assessing hearing levels across the frequency range, five case studies were conducted measuring participants hearing using pure tone audiometry and the sweep frequency program. Participants were also asked to rate the accuracy to which they responded to the sweeping stimulus. Results showed that for testing at supra threshold levels, the feasibility of utilising the program as a screening tool was supported. The influence of decreasing the sweep rate was determined to enhance the accuracy of the responses elicited. The onset of tinnitus in participant four showed increased variance in responses in relation to the sweep signal. Furthermore it was witnessed that variations in responses in comparison to pure tone audiometry highlight the degree to which an accurate representation of hearing levels can be obtained. This study shows the potential application for the implementation of the sweep frequency program stemming from the nature of the results obtained.