Cooledit 2

Sentences of the KS-SL-A were used in the study as stimuli [10 ]. A total of 80 sentences were used, with 8 sets of 10 sentences per set. Each test set comprised 40 keywords. Sentences were mixed with speech-shaped noises, which were matched to the spectrum of the sentences to create signals that varied in SNR. Three SNR conditions were used (-5, 0, +5 dB SNR). The noisy sentences were adjusted to have a level of 45 dB HL [12 ]. The noisy speech sentences were then filtered through both low- and high-pass filters (224, 447, 891, 1,413, 2,239, 3,548, 5,623, and 11,000 Hz) using Cooledit 2.0 (ADOBE systems, San Jose, CA, USA). Band widths were selected at regular intervals in 1/3 octave band cutoff frequencies [13 (link)]. We used linear-phase finite impulse response filters with a rejection slope of 96 dB/octave at the desired cutoff frequencies.

To generate the filtered stimuli, an audio program (Cooledit 2.0, Adobe Systems, San Jose, CA, USA) was used. The stimuli were routed to an audiometer (GSI61; Grason-Stadler, Eden Prairie, MN, USA) and presented to the participant's right ear through a headphone (TDH-50P; Telephonics Corporation, Farmingdale, NY, USA).