Figure 1.

Reverberation stimuli and their acoustic characteristics. (A–D), Spectrograms for the vowel /i/ with time-varying fundamental frequency and formants F1 = 300; F2 = 2500; F3 = 3500; F4 = 4530 Hz. The addition of reverberation was accomplished by time domain convolution of the original vowel with room impulse responses recorded in a corridor at a distance of either 0.63 m (mild reverb; Reverberation Time (RT₆₀) ≈ 0.7 sec), 1.25 m (medium reverb; RT₆₀ ≈ 0.8 sec), or 5 m (severe reverb; RT₆₀ ≈ 0.9 sec) from the sound source (Sayles and Winter, 2008; Watkins, 2005). With increasing reverberation, spectral components (top row) and the time waveform (bottom row) are “smeared”, resulting in a blurring of the fine time-frequency representation of the vowel (compare “dry” to “severe” condition). (E), FFT spectra over the duration of the stimuli as a function of reverberation strength. Smearing of high frequency spectral components (induced by blurring in the waveform’s temporal fine-structure) is evident with increasing levels of reverberation. However, note the relative resilience of the fundamental frequency (F0: 103–130 Hz) with increasing reverb.