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.