Fig. 1.

Experimental stimuli and derived-band procedure. a Schematic representation of the derived-band recording procedure, which involves subtracting high-passmasked responses for successive high-pass (HP) cutoff frequencies (2 and 4 kHz in this example). The HP noise is shown by the grey highlight, and the background (BG) noise is shown by the pink and red highlights (representing the two noise levels used). b Spectrogram of the /da/ syllable. The abscissa shows time, the ordinate shows frequency, and spectral energy is shown by the grey scale (with darker greys indicating increased energy). c Overall spectra of experimental stimuli as delivered through the ER-1 insert earphones used. The black line shows the /da/ syllable, the grey line shows an example high-pass noise with a 1-kHz cutoff frequency, and the pink and red lines show the full-spectrum background noise at the two signal-to-noise ratios (SNRs) used (20 and 10 dB, respectively). When presented in conjunction with a high-pass noise, the background noise would be low-pass-filtered at the HP cutoff frequency