Automated Speech Intelligibility System for Head-Borne Personal Protective Equipment: Proof of Concept

Abstract : An automated objective test system was developed to assess the impact of head-borne personal protective equipment on speech intelligibility and transmission. The system comprised talker and listener headforms, speech recordings, and speech recognition software. A recording of sentences from the Speech Perception in Noise test was transmitted from the speaker in the talker headform to microphones in the ears of the listener headform. The speech recognition software recorded the speech received at the listener headform. The responses were scored by hand. Speech transmission was assessed by separately placing two air-purifying respirators on the talker headform while speech intelligibility was evaluated by separately placing a chemical protective suit, an escape respirator with hood, and a ballistic helmet on the listener headform. A control condition with bareheaded talker and listener headforms was run for comparison. Speech transmission was statistically significantly degraded by both respirator conditions compared to the control condition. The protective suit and escape respirator both caused statistically significant decreases in speech intelligibility compared to the control and helmet conditions. These results show that an automated test system has been developed that can be used to quantify degradations in speech transmission and intelligibility when head-borne personal protective equipment is worn.