Speech intelligibility assessment in a helium environment

Area of Science:

• Audiology
• Speech Science
• Diving Physiology

Background:

• Underwater communication systems for Navy divers present unique challenges due to helium speech.
• Evaluating the intelligibility of speech in noisy, helium-rich environments is crucial for diver safety and operational effectiveness.
• Existing speech perception tests may vary in their suitability for assessing communication in these specialized conditions.

Purpose of the Study:

• To compare the effectiveness of the Speech Perception in Noise (SPIN) test and the Griffiths Version of the Modified Rhyme Test (GMRT).
• To assess Navy divers' speech understanding through communication systems with different helium speech unscramblers (HSUs).
• To evaluate the influence of listening conditions (taped vs. live-voice) on speech perception test performance.

Main Methods:

• Participants included Navy divers during saturation dives and a control group of non-divers.
• Digital audio recordings of stimuli were used, simulating diver-to-diver and topside-to-diver communication.
• Performance was measured using mean percent correct scores on both SPIN and GMRT lists across two listening conditions.

Main Results:

• Mean correct scores on SPIN and GMRT were nearly identical across tested conditions.
• Listeners performed better in the topside-diver (taped) condition compared to the diver-diver (live-voice) condition.
• SPIN test errors were predominantly on low-predictability, context-poor items, indicating context's importance.

Conclusions:

• Both SPIN and GMRT are comparably effective for assessing speech understanding in Navy divers using HSU systems.
• The listening condition significantly impacts speech perception scores, with taped, topside-diver communication yielding better results.
• Contextual information plays a vital role in speech perception, especially for the SPIN test, in these communication scenarios.