44th aes conference (2011)

PowerPoint Presentation

lvaro Barbosa, Joo CordeiroResearch Center for Science and Technology of the ArtsCITAR (UCPPorto, Portugal)

The Influence of perceptual Attack times inNetworked Music performance

Pilot Study conducted at CCRMA, Stanford University (2011)

1

Latency and Networked Music

In a vocal conversation it is possible to maintain it even with one-way delays of up to 500 ms.Holub, J., Kastner, M., Tomiska, O. 2007In order to maintain a synchronized and smooth musical interaction reduces drastically to the order of tens of milliseconds.Schuett, N. 2002 Chafe C., Gurevich M, 2004 Lago, N and Kon, F. 2004Barbosa, A., Cart, A. 2005Chew, E., Sawchuk, A., Tanoue, C., and Zimmermann, R. 2005 Bartlette, C., Headlam, D., Bocko, M., Velikic, G. 2006 Farner, S., Solvang, A., Sbo, A., Svensson, U. P. 2009 Chafe, C., Cceres, J-P., Gurevich, M., 2010

Background on Network Music Performance


For the Human ear to perceive the order of two simultaneous sounds, they should not be displaced in time over 20ms (Hirsh, 1959)

A difficulty in discerning the order of sounds eventshard to maintain a synchronous musical interaction.Background on Network Music Performance


The ability to perform music synchronously is strongly dependent on:The music expressive qualities (Dynamics and Articulation)The music style (rhythm, melody, harmony)The music perceptual qualities (pitch, texture, timbre)The music structure/formThe musicians experience and practicing strategiesComplementary feed-back modalities (visual, tactile)The listening conditionsBackground on Network Music Performance


Basic Principles(1) Ensemble Performance Threshold (EPT)(2) Echo Feed-Back (Self Delay)(3) Inverse Proportion to Tempo (4) Reverb and Complementary Modalities(5) Slow Attack TimesBackground on Network Music Performance

(1) Ensemble Performance Threshold (EPT) (CCRMA 2004, USC 2005)Background on Network Music Performance

(2) Echo Feed-Back (USC 2005)Background on Network Music Performance

Chew, E., Sawchuk, A., Tanoue, C., and Zimmermann, R. 2005

(2) Echo Feed-Back (UCP-Porto 2005)Background on Network Music Performance

(3) Inverse Proportion to Tempo (UCP-Porto 2005)Background on Network Music Performance

(3) Inverse Proportion to Tempo (CCRMA/Banff 2006)Background on Network Music Performance

St. LawrenceString Quartet(over 50ms Delay)

(4) Reverb and Complementary ModalitiesBackground on Network Music PerformanceStudies on the effect of Reverberation

(Farner 2009)The Influence of Delay and Various Acoustic Environments

Studies on the effect of Visual Feed-Back

Pilot experiments at CCRMA since 2006

Studies on the effect of Haptic Feedback ???

(5) Slow Attack TimesThe Influence of Attack Times in NMP

Bregman (1990) Auditory Scene AnalysisThis experiment clearly reveals that it is harder to perceive the order of overlapping sound events when their rise time (attack) is slower.

In other words, overlapping sounds with slower rise times are better perceived as synchronous even when their onsets are not physically simultaneous.

The Time delay between clusters is 120 ms12

The Influence of Attack Times in NMPPerceptual Attack Time (PAT)

The fact that two sounds are physically synchronous does not necessarily make them sound perceptually synchronous.

Perceptual Attack Time (PAT) is a subjective measure of the time that is perceived by the listener as the moment of rhythmic placement for a musical sound event.

According to Matt Wrightfor highly percussive sounds, the PAT might be the same as, or just a few milliseconds after, the onset time, but for sounds with a slow attack, for example, bowed violin, the PAT might be dozens of milliseconds after the onset.

13

The Influence of Attack Times in NMPPilot Study Hypothesis

If slow attack times allow a better perception of sound simultaneity this might also lead to a better ability to perform synchronous musical interaction

Experimental Setup

14

The Influence of Attack Times in NMPRhythmic Performance80 BPM (to avoid possible overlaying of subsequent notes)Slow Tempo => Higher EPTRange from 25 ms to 110 ms (with steps of 10 ms)28 trials for Slow and Fast attack strokes

15

The Influence of Attack Times in NMPResults #1Could each musician maintain a 80 BPM steady rhythm, throughout the range of latencies introduced on the feedback loop?We performed the analysis of the average BPM progression with the Tempo and Beat Tracker tool from Queen Marys Sonic Visualizer.

16the average Tempo fluctuation for each trial decreases while latency increases (which is consistent with the inverse proportion between Tempo and EPT)individually and in average, each performer is able to maintain a rhythm closer to the initial metronome Trigger (80 BPM) when performing fast attack bowed strokes.

The Influence of Attack Times in NMPResults #2How each musician performs in relation to the other?analysis was performed using the software tool MATCH: Music Alignment Tool Chest, developed by Simon Dixon (this software analyses the alignment of audio files using the OLTW algorithm)

17the performance with slow attack is always closer to the value 1, which indicates a better proximity in the alignment of sound events from the two performances

The Influence of Attack Times in NMPConclusions & Future Work

The results from the Attack Time Pilot Experiment suggest that for higher latencies than the generally established EPT (20-40 ms), a better musical performance can be achieved when musical notes are played with slow attack times.

Further investigation remains to be done, specifically by expanding the experiment to a larger number of subjects and a larger scope of musical instruments.

It remains to be determined what is if there is a functional relationship between the rise times of Attack in musical notes and the performance Tempo, that affects the EPT.

18the performance with slow attack is always closer to the value 1, which indicates a better proximity in the alignment of sound events from the two performances

Thank You!!!!

[email protected] | http://www.abarbosa.org

[email protected] | http://www.joaocordeiro.eu

19

Blues56316.57