Research PaperPerformance in noise: Impact of reduced speech intelligibility on Sailor performance in a Navy command and control environment

- Noise and hearing loss are common problems in the military that can impair speech intelligibility.
- Understanding effects of speech intelligibility levels is vital for determining mission success and risks.
- Performance in a variety of measures is impacted when communications is disrupted by decreased speech intelligibility.
- Often compensation strategies are not sufficient to prevent real world performance declines when hearing is poor.

Noise, hearing loss, and electronic signal distortion, which are common problems in military environments, can impair speech intelligibility and thereby jeopardize mission success. The current study investigated the impact that impaired communication has on operational performance in a command and control environment by parametrically degrading speech intelligibility in a simulated shipborne Combat Information Center. Experienced U.S. Navy personnel served as the study participants and were required to monitor information from multiple sources and respond appropriately to communications initiated by investigators playing the roles of other personnel involved in a realistic Naval scenario. In each block of the scenario, an adaptive intelligibility modification system employing automatic gain control was used to adjust the signal-to-noise ratio to achieve one of four speech intelligibility levels on a Modified Rhyme Test: No Loss, 80%, 60%, or 40%. Objective and subjective measures of operational performance suggested that performance systematically degraded with decreasing speech intelligibility, with the largest drop occurring between 80% and 60%. These results confirm the importance of noise reduction, good communication design, and effective hearing conservation programs to maximize the operational effectiveness of military personnel.