Tapping into the Internet as an Acoustical / Musical ...cc/pub/pdf/tapInternetMedium.pdf · Tapping...

Interactive Networked Music --Tapping into the Internet as anAcoustical / Musical Medium

Chris Chafe

Center for Computer Research inMusic and Acoustics (CCRMA)

Stanford University

Our theme as a magazine cover...

(ACMDec-01)

(Dec-06)

Stanford Chicago

RPI, NYSanta Cruz

Analogies to other acoustical media: air, water, earth, etc.

topologies

Acoustical Monitoring for Network Operations(NASA)

Interactive Sound Art / Theater(SF MOMA, Parc de la Villette)

Distributed Musical Ensembles

Distributed Instrument Synthesis (Physical Models)

Distributed DSP Algorithms (Internet Reverb)

Applications:

Studies:

Studies of Rhythm Locking under Delay Conditions

Thoughts on the Qualities of an IP Acoustical Medium

Duo PianoConcert

Stanford / Belfast

(15-May-07)

Jam SessionStanford ?? (2002)

next studio?Berkeley?

Sacramento?Denver

Chicago

Montreal

London

Bass & Saxat Stanford

Listening quiz: The drums are where?

Drums are inMontreal

Bass & Saxat Stanford

Jam SessionStanford McGill Univ. (2002)

Jam SessionsStanford McGill Univ. (2002)

Round trip time (ms)Stanford Princeton

Quintet (June, 2006)Banff, Alberta (St. Lawrence String Qt.)CCRMA, Stanford (2nd viola)

(25 msec oneway)


Listening from Banff side


Listening from Stanford side

Quintet (June, 2006)Banff, Alberta (St. Lawrence String Qt.)CCRMA, Stanford (2nd viola)


The Perfect Ritard


The Perfect Ritard

Egads! A new use forthe Internet.


Fighting off the Ritard


Fighting off the Ritard

Hmm... wishful thinking.


Power Structure, the 4 ignore the 1(music minus one)

4 players

1 player follows


Power Structure, the 4 ignore the 1(music minus one)

4 players

1 player follows

Best! ...but result is onesided.

Here's what happensjust across a room... (length of room, ca. 20 feet)

4 players

Quartet, recorded in a room.Take 1: all together in one corner

4 players

Take 2, separated by a partition

3 players

exiled violist

Take 2, after recording,compensated by 21 msec

Summary:

Separation delay is like molasses (slows tempo down)

Equality of ensemble makes it worse

Tactics to compensate (“y ou lead, I'll follow”)

Post-production compensation

Room and reverb seem to help

Let's make some music, anyway.

Trio (May, 2004)Stanford (bass guitar) / Victoria, BC (sitar) / Missoula, MT (elec. Violin)


Quartet (June, 2004)Stanford (flute, elec. cello)Stockholm (bass flute, piano)

...really slow tempo,not much rhythm...


Octet (March, 2006)Stanford (violin)Seattle (uilleann pipes)Belfast (sextet)

...fast, rhythmic...

Round trip time (ms)Stanford PrincetonNext gig?

Experiment Designed toDetermine Effect of Latency onEnsemble Accuracy

Subjects = students and staff at Stanford(paired randomly)

Task = play rhythm accurately, keep an even tempo(no strategies given)

Interlocking rhythm

Sound(2ms delay each direction, metronome cue = mm94)

Delays: 0 – 77ms (each way) in 12 steps

Experiment 1 with 17 pairs of subjects

0 25 9

1420

2735

44

54

65

77

Delay Times (ms) Tested

Deceleration from longer delaybut where does it start to cause

trouble?

Sound(77ms delay each direction, metronome cue = mm90)

Results

Human clappers at 65ms delay

Acceleration vs. delay time(r2 = 0.98)

Tempo slope = 0

Delay = 11.5 ms

@ Delay 11.5 ms, 85% of trials slowed down

Sweet Spot?

Rhythm Locking

new field of study, useful for applicationssimilar to turn taking studies

we like to lock, music, dance, ...physical, fun

clumsy locking is frustrating

and tech stuff can really mess it up(i.e., bad network audio) but, also human stuff

Analogies to other acoustical media: air, water, earth, etc.

speed of sound

due to network delay jitter and asymmetrythe speed of sound is never uniform

(but there are also special LAN digital audio networks using dedicated hardware which are constant)

never uniform

easy to interpret by ear...

sonified pings Stanford www.newscientist.com

sound quality

depends on QoS of network pathand hosts' network and audiocapabilities

...test with audio feedback loops

fast echoes = pitches

SoundWIRE “ plucking” technique, recirculates audio for fine-grained QoS monitoring

Stanford UCBerkeley

changing delay = variable speed of sound = potential signal discontinuities = sonic booms

packet transmission errors = glitches from dropped data or duplicates

anisotropic

in wood, speed of sound isfaster with the grain

in network, speed of sound is faster in the corebut slows down near the edges where there's often lots of routers

asymmetric

speed never exactly the same bidirectionally

Best match: < 25ms = longest delay > 25 ms = mean of delays

Asymmetry

no distance effects on signal = no attenuation, filtering or dispersion

no mixing =wave channels can be 100% discrete

SummaryInternet acoustics, same but differentMore than just a telephone because there's computing involved...musical instruments, spaces, effects are created in software...and prediction algorithms

Thanks!

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