Evidence-based occupational hearing screening II: validation of a screening methodology using measures of functional hearing ability

Objective: Validate use of the Extended Speech Intelligibility Index (ESII) for prediction of speech intelligibility in non-stationary real-world noise environments. Define a means of using these predictions for objective occupational hearing screening for hearing-critical public safety and law enforcement jobs. Design: Analyses of predicted and measured speech intelligibility in recordings of real-world noise environments were performed in two studies using speech recognition thresholds (SRTs) and intelligibility measures. ESII analyses of the recordings were used to predict intelligibility. Noise recordings were made in prison environments and at US Army facilities for training ground and airborne forces. Speech materials included full bandwidth sentences and bandpass filtered sentences that simulated radio transmissions. Study sample: A total of 22 adults with normal hearing (NH) and 15 with mild–moderate hearing impairment (HI) participated in the two studies. Results: Average intelligibility predictions for individual NH and HI subjects were accurate in both studies (r² ≥ 0.94). Pooled predictions were slightly less accurate (0.78 ≤ r² ≤ 0.92). Conclusions: An individual’s SRT and audiogram can accurately predict the likelihood of effective speech communication in noise environments with known ESII characteristics, where essential hearing-critical tasks are performed. These predictions provide an objective means of occupational hearing screening.