Speech intelligibility testing of general service respirators

The communication performance of three general service respirators was evaluated. The evaluation procedure followed a NIOSH standard test procedure which is based on a modified rhyme test (MRT), wherein human participants are placed in a controlled acoustic environment and are asked to read out lists of test words. The number of words correctly identified by a listener panel when the talker is wearing the respirator is compared to the number of words correctly identified without the respirator, giving an overall performance rating. During the implementation of the experimental procedure, it was noted that the NIOSH test procedure is ambiguous on a number of potentially significant acoustical issues, e.g., the reverberation time of the test environment, the background noise spectrum at the listener position, and the talker voice level. This talk will present details of the study and discuss the relevant issues related to speech intelligibility testing of respirators that were evaluated as part of this project.