10th Speech in Noise Workshop, 11-12 January 2018, Glasgow

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Development and evaluation of the Coordinate Response Measure speech-in-noise test as a hearing assessment tool for the Armed Forces

Hannah Domenica Semeraro(a), Daniel Rowan
Institute of Sound and Vibration Research, University of Southampton, UK

(a) Presenting

The ability to listen to and understand commands in noisy environments, whilst maintaining situational awareness, is an important skill for military personnel and can be critical for mission success. Accurately measuring auditory fitness for duty (AFFD) within the Armed Forces ensures that personnel have sufficient hearing ability to be effective in operational scenarios. Pure-tone audiometry (PTA) is currently used by the UK military but it is known to be a poor predictor of overall listening ability. In addition, conducting accurate audiometry presents some practical challenges in occupational environments. Here we suggest a speech-in-noise test as an alternative AFFD assessment tool and explain how simulations of speech-communication mission-critical auditory tasks (MCATs) were developed to explore the predictive validity of potential AFFD tools.

Firstly, we developed a British English version of the CRM using call signs from the NATO phonetic alphabet. After ensuring all the target words had similar intelligibility, the CRM was implemented in an adaptive procedure in stationary speech-spectrum noise to measure speech reception thresholds (SRTs). The SRTs of normal-hearing civilians and hearing-impaired military personnel were assessed. The CRM is sensitive to hearing impairment and the results display good test-retest reliability (95% confidence interval < 2.1 dB) and good concurrent validity when compared to the Triple-Digit-Test (r = < 0.65).

Secondly, we developed simulations of the speech-communication MCATs in order to explore the relationship between performance on potential AFFD tools and performance when listening to ‘real world’ stimuli. Participants included normal-hearing civilians (n=28) and military personnel (n=28). We also explored the influence of military experience when listening to commands. Participants listened to commands recorded over a military radio, presented in armoured vehicle engine noise at a fixed SNR and processed through a hearing loss simulator. The percentage of correctly repeated commands was scored. Participants also completed the CRM adaptive procedure. Results showed that both the simulated commands and CRM are sensitive to simulated hearing impairment. Military personnel outperform civilians on the commands but not on the CRM, suggesting that personnel are, to some extent, able to use their knowledge and experience of command structure and vocabulary to overcome adverse listening conditions and compensate for hearing impairment.

Further work is required to determine whether PTA or the CRM, when combined with additional information about non-psychoacoustic factors that may influence performance, such as military experience, best predict AFFD.

Funding — The Royal Centre for Defence Medicine.

Last modified 2017-11-17 15:56:08