2.4.1 Speech Discrimination Scores in Quiet
Speech perception in quiet was measured using the speech discrimination score (SDS, in %, at 65 dB SPL speech presentation level). The speech signal was a 50-disyllabic word list randomly selected from 10 equivalent word lists in MSTMs [8] and was played from a loudspeaker in front of the subject at ear level at a distance of 1 m. In the SSD group, an earmuff and an earplug in the external auditory canal were used to plug the healthy ear to minimise the potential “eavesdropping effect” from the contralateral ear. This plug effect produced an average attenuation of 57 dB from 250 Hz to 8000 Hz.