Abstract:

The drawback for speech understanding of wearing sound attenuating earplugs and muffs in combination was investigated. Two groups of normal-hearing subjects were tested in backgrounds of low-frequency cable swager and speech spectrum noise, respectively. Consonant discrimination was assessed using the Four Alternative Auditory Feature Test [J. R. Foster and M. P. Haggard, Proc. MRC Inst. of Hearing Res., UK, 9--12 (1979)], in a semi-reverberant chamber that met the specifications of ANSI 12.6-1984. Speech materials were presented free field at a level of 85 dB SPL, in quiet and mixed with noise levels of 80--95 dB SPL. Subjects were tested with the ears unoccluded and fitted with E-A-R foam plugs, Peltor muffs with ANR capability, and the plugs and muffs, with and without ANR operational, in combination. Preliminary results showed that consonant discrimination decreased with S/N ratio. There was no difference due to the protector condition for speech spectrum noise. In contrast, in the low-frequency cable swager noise, subjects showed greater variability in performance across listening conditions, with relatively poorer scores for the combinations. [Work supported by National Defence Canada.]