Effect of reverberation on loudness perceptionInsert footer on Slide Master© University of Reading Department of Psychology 12 May 2015 Effects of reverberation on loudness perception Andrew Raimond

Effect of reverberation on loudness perception2 Overview Previous Experiments –Pilot; Real-room reverberation; Mono v Dichotic. Current Experiments –Time order effects –Effects of frequency bands

Effect of reverberation on loudness perception Loudness asymmetry 3 Time Amplitude Damped Sound Ramped Sound Damped Ramped Attack Decay Attack Decay

Effect of reverberation on loudness perception Loudness context effect 4 Which is loudest? Time Ramped Damped Damped Ramped Ramped Damped

Effect of reverberation on loudness perception Reverberation The “tails” on damped stimuli resemble effects of room reflections (Stecker & Hafter, 2000; Watkins, 2005). 5 Dry speech Reverberated speech Dry Speech Reverberant Speech

Effect of reverberation on loudness perception Loudness judgement 6

Effect of reverberation on loudness perception Questions Perceived reduction in loudness of damped stimuli relative to ramped stimuli –is this still apparent with sounds that have tails processed from real- room reflections? The loudness context effect –is this still apparent with sounds that have tails processed from real- room reflections? 7

Effect of reverberation on loudness perception Real-room reverberation However, tails added by real-room reverberation differ from the envelopes used by Stecker & Hafter: - Real-room decays are not smooth - Durations of real-room decays are usually longer - Room-reflections de-correlate the signal at the two ears 8 Left Channel Right Channel

Effect of reverberation on loudness perception Experiment 1: Real-room Can real-room reverberation over-ride artificial shaping used by Stecker & Hafter? Perceived reduction in loudness of damped stimuli relative to ramped stimuli? The loudness context effect? –Loudness asymmetry –Loudness context effect –Convolution with real-room reverberation overrides shaping used by Stecker & Hafter. –Effects of real-room reflections are more substantial than shaping used by Stecker & Hafter 9

Effect of reverberation on loudness perception Experiment 2: Monaural v Dichotic Certain room-reflection ‘tail effects’ that have been found in speech perception experiments are increased in monaural conditions (Watkins, 2005). Is the loudness context effect also increased when sounds are presented in monaural real-room reverberation? –Loudness asymmetry –Loudness context effect –Effects of the real-room tails successfully oppose effects of the function-shaped tails, as there was a substantial context effect that depended on the direction of the real-room tail. –As with ‘tail effects’ in speech, this context effect is found in both monaural and dichotic conditions, but is less prominent in dichotic conditions. –There appears to be a ‘de-reverberation’ in dichotic conditions that may be due to the de- correlation between the two ears’ signals with the real-room BRIRs 10

Effect of reverberation on loudness perception11 Damped-Ramped Ramped-Damped Ramped-Ramped Damped-Damped 1700 ms 1350 ms 1000 ms (Loudest) (Least loud) Experiment 3: Time order effects Time 500 ms ISI

Effect of reverberation on loudness perception12 Experiment 3: Time order effects Ramped- Ramped 850 ms Damped- Damped 850 ms Peak-to-Peak 1700 ms Damped- Ramped 500 ms Ramped- Damped 1200 ms 850 ms

Effect of reverberation on loudness perception 2IC task. Pure tones of equal power (330 Hz, 250 ms). Gated with either Ramped or Damped envelope, convolved with real-room 2.5 m BRIRs. Played through left channel. Standard stimulus (80 dB SPL), then ISI of 500,850,1200 or 1550 ms Then Test stimulus (selected at random from 70,72,.., 90 dB SPL) Which is loudest? 13 Experiment 3: Time order effects

Effect of reverberation on loudness perception Damped Test Experiment 3: Results ms ISI Proportion Test > Standard responses Test level (dB SPL) Ramped Standard Damped Standard Ramped Test P.S.E

Effect of reverberation on loudness perception Damped Test Ramped Test Experiment 3: Results ms ISI Proportion Test > Standard responses Test level (dB SPL) Ramped Standard Damped Standard P.S.E

Effect of reverberation on loudness perception Damped Test Ramped Test Experiment 3: Results ms ISI Proportion Test > Standard responses Test level (dB SPL) Ramped Standard Damped Standard P.S.E

Effect of reverberation on loudness perception Damped Test Ramped Test Experiment 3: Results ms ISI Proportion Test > Standard responses Test level (dB SPL) Ramped Standard Damped Standard P.S.E

Effect of reverberation on loudness perception Experiment 3: Pooled Results 18 Ramped Damped 850 ms ISI 500 ms ISI Total Proportion Test > Standard Responses Ramped Test Damped Test Standard Type Ramped Damped

Effect of reverberation on loudness perception Experiment 3: Pooled Results 19 Ramped Damped 1550 ms ISI1200 ms ISI Total Proportion Test > Standard Responses Ramped Test Damped Test Standard Type Ramped Damped

Effect of reverberation on loudness perception Proportion Test > Standard responses Damp test 850 ms ISI Ramp test 500 ms ISI Experiment 3: Results 20 Equal Peak-to-Peak Times Test level (dB SPL) P.S.E Damp test 1200ms ISI Ramp test 850ms ISI Damped StandardRamped Standard P.S.E

Effect of reverberation on loudness perception Experiment 3: Conclusions 21 Loudness asymmetry and loudness context effect are not dependant on Peak-to-Peak distance. While still able to make loudness judgments, loudness asymmetry disappears with ISIs longer than 850 ms.Thus, loudness context effect does so too. However, standard only contains one 300 ms reverberant tail, in one frequency region. Wideband (speech) contexts contain many more reverberant tails.

Effect of reverberation on loudness perception Experiment 4: 22 Ongoing experiments: Effects of frequency bands

Effect of reverberation on loudness perception Experiment 4: Effects of frequency bands 23 Perceptual constancy for reverberation is more effective within wideband sounds (Watkins & Makin, 2007). Perceptual mechanism seems to operate on a band-by-band basis. Test and standards used in Stecker & Hafter and in previous experiments have all occupied the same narrowband frequency region (300-Hz). Use standards and test sounds in different frequency bands to examine loudness asymmetry Investigate if loudness context effects are still apparent with cross-band standards and test sounds.

Effect of reverberation on loudness perception Thanks Thank you! 24