Frequency-modulation (FM) technology as a method for improving speech perception in noise for individuals with multiple sclerosis

Almost half of the population with multiple sclerosis (MS) complains of difficulty hearing, despite having essentially normal pure-tone thresholds. The purpose of the present investigation was to evaluate the effects of frequency-modulation (FM) technology utilization on speech perception in noise for adults with and without MS. Sentence material was presented at a constant level of 65 dBA L-eq from a loudspeaker located at 0 degrees azimuth. The microphone of the FM transmitter was placed 7.5 cm from this loudspeaker. Multitalker babble was presented from four loudspeakers positioned at 45 degrees, 135 degrees, 225 degrees, and 315 degrees azimuths. The starting presentation level for the babble was 55 dBA L-eq, The level of the noise was increased systematically in 1 dB steps until the subject obtained 0% key words correct on the IEEE (Institute for Electrical and Electronic Engineers) sentences. Test results revealed significant differences between the unaided and aided conditions at several signal-to-noise ratios.