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Rhythm and Meter Rhythm and Meter

Rhythm and Meter - PowerPoint Presentation

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Rhythm and Meter - PPT Presentation

Note Perception of groupings Mike Oldfield Tubular bells theme song for the Exorcist Beat Beat underlying even pulse common in many types of music Range typical of that given on a metronome ID: 172064

rhythm beat beats variations beat rhythm variations beats time sethares sound tempo onsets meter midi experiments note timbre clip intervals image microtiming

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Slide1

Rhythm and Meter

Note Perception of groupings

Mike Oldfield, Tubular bells, theme song for the ExorcistSlide2

Beat

Beat – underlying even pulse common in many types of musicRange typical of that given on a metronome

frequency 30 to 200 beats/minute OR 0.5-4 Hz p

eriods between 250ms and few seconds.For clicks closer together than 100 ms, they run together.Separated longer than a few seconds we don’t feel that they are associated

same range as sung

vibratro

or tremolo, or heartbeat

beats we

feel

are slower than frequencies we

hear

We tend to move spontaneously to the beat.

Newborn babies respond to the beat (e.g. Winkler et al. 2009 – recent press on this, as seen from electric signals picked up near the brain).Slide3

Areas of the brain (as seen by

fMRI (functional magneto resonance imaging) respond to regular beats

Grahn

& Brett (2007), Journal Cognitive Science 19:5, 893Slide4

Expectations and Tapping experiments

First listen.

Then everybody tap after the sound file endsThis is the first beat pattern in the next figure and based on one of Dessain’s experimentsSlide5

Expectancy of next beat

Peter

Dessain, Music Perception: An Interdisciplinary Journal, Vol. 9, No. 4

(1992), pp. 439- 454

tapping experimentsSlide6

Tapping experiments

Dessain

92 Slide7

Time shrinking

D

uration of short time intervals is conspicuously underestimated if they are preceded by shorter neighboring time intervals.

Figure by Petra Wagner and Andreas WindmannSlide8

Sound clip from

http://listverse.com/2008/02/29/top-10-incredible-sound-illusions/Slide9

Subjective duration

Figure from Psychoacoustics by

Zwicker and Fastl

Note decaying envelopes are not heard as they are equivalent to echoes and so are

suppressed

.

Because of this we would have expected that the flat top would be half the interval for the perception of 1/8

th

note. But this is not the case.

Slide10

Groupings

Images and three sound clips from W.

Sethares

book on Rhythm and Transform

with different timbres

19/20Slide11

Necklace Notation

Images and clips from Rhythm and Transform by W.

Sethares

With different timbre emphasis the perceived starting position variesSlide12

Necklace Notation

Images and clips from Rhythm and Transform by W.

SetharesSlide13

Numerical Notations

Image and clip from Rhythm and Transform by W.

SetharesSlide14

MIDI event data

MIDI =

Musical Instrument Digital Interface)

MIDI DATA

CHANNEL

TIME

NOTE

DURATION

VELOCITY

Measures

beat ticks

beats+ticks

velocity/off

1

4:3:0

F2

1:100

100:64

A certain number of ticks makes up each beat

image from audacitySlide15

Tabla

Talas

Image from http://www.chandrakantha.com/tablasite/quick.htmSlide16

Science of

Tabla

Image and clip from http://

www.chandrakantha.com/tala_taal/jhoomra/jhumra.html

Figure From Rhythm and Transforms by W.

Sethares

JhumraSlide17

Hierarchy of levels

David Rosenthal, Computer

Music Journal, Vol. 16, No. 1

(1992), pp. 64-76Slide18

Measures/Beats/Tatums

Measures: groupings of beats, repeating Cyclic pattern of rhythm if repetitive

Beats: underlying pulseTatums or Ticks. Small unit of time. Beats and note onsets are described in units of tatums from the beginning of measure or cycleAbove is an example of a hierarchy

Classification of a series of onsets into a type of rhythm based on minimizing the complexity of the required hierarchy or minimizing the syncopation.Slide19

Microtiming measurements

for a Samba

While we might perceive a rhythm in terms of regular intervals, however musicians may with systematic small deviations from calculated intervals/durations

Fabien Gouyon

, SBCM 2007 proceedings Slide20

Microtiming Variations

Fabien

Gouyon, SBCM 2007 proceedings

systematic shifts in timing of order 20ms associated with musicianship and musical style/genreSlide21

Bar Wrapping Visualization of Meter

Matthew Wright et al. 08

ISMIR 2008 – Session 5c

Tempo is varying

Beat identification done in software

Microtiming

variations then shown in this way

tempo

timeSlide22

Musicianship in timing

Note double hits

by bass Percy

JonesDifferences in timing of bass compared to drum make each instrument stand out yet rhythm is still strongSlide23

Rubato

Harpsichord and rubato,someday a good clip will

illustrate this!Slide24

Onsets

Opposite of synthesis Groups of overtones moving together appear as one sound

Fast clicks appear as one element Any factors that can create auditory boundaries can create patterns in time that can be perceived as rhythmic (following Sethares’s statement in 4.3.8).

-- Boundaries = Quick Variations in timbre, pitch or loudnessSlide25

Algorithms for Finding Onsets

Can be referred to as Feature vectorsReduce sampling rate

Partition into frequency bandsSearch for variations in total energy (volume) spectral mean or center, spectral dispersion or large variations in energy in any particular bandSoftware developed such as beatroot outputs a MIDI event file of onsets

With beatroot you can adjust location of individual onsets and add or remove themSlide26

Finding meter and tempo

For tempo:Autocorrelation or Fourier methods (J. Brown)P

eriodicity transforms (Sethares)These fail if the tempo is varyingAdaptive oscillators work if tempo varies smoothlyPerceptive idea of “internal clock”

Hierarchy of levels to identify meter (Rosenthal)Minimization of number of syncopations (Longuet-Higgens & Lee 84)Statistical modelsIf you have a score or a MIDI file then synching the sound file may be more straightforward

My impression is that this is an active area of research

Slide27

Musicianship in rhythm

Not captured by simple descriptions or classifications of rhythms:

meter changes, accent changesaccelerandos and ritardos (tempo variations)

microtiming variations Delays or jumps shifting the entire beat,

bending time

Displacements, delays or jump in onsets that don’t change the beat

timbre variations --- different types of sounds (like different drums) substituted

omissions, doublings of strokes

graces notes added

rhythm pattern reset (shifted?) or variedSlide28

Hacking a recording to change meter

James Bond Theme Song by Monty Norman- arranged by John Barry and from the movie Dr. No

Bond Waltz - W.

Sethares

B

eat regularization or stretching for effect can be done in the studio, but software is not necessarily standardized or cheep.

Beat tracking allows interesting composition experiments (such as above)

-For other compositional ideas see

Sethare’s

sound clips in his bookSlide29

Remake atrocious

Lao Schifrim

Adam ClaytonSlide30

Character of song can remain despite large timbre changes

Christopher

Tyng