Rhythm Day 21

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Rhythm Day 21

• Music Cognition
• MUSC 495.02, NSCI 466, NSCI 710.03
• Harry Howard
• Barbara Jazwinski
• Tulane University

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Course administration

• Spend provost's money

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Goals for today
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The elements of rhythm

• Rhythm is the variation of the length and
  accentuation of a series of sounds or other
  events.
• Much music is characterized by a sequence of
  stressed and unstressed beats (often called
  "strong" and "weak") organized into a meter and
  partially indicated by a time signature, the
  speed of which is determined by a tempo.

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Beat

• The basic time unit of much Western music
• each tick sounded by a metronome

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Types of beats

• Downbeat
• The impulse that occurs at the beginning of a bar
  in measured music, typically the first beat of a
  measure.
• Its name derives from the downward stroke of the
  director or conductor's baton at the start of
  each measure.
• Upbeat
• An unaccented beat or beats that occur before the
  first beat of a following measure.
• In other words, it is an impulse in a measured
  rhythm that immediately precedes, and hence
  anticipates, the downbeat, which is the strongest
  of such impulses.
• It is also an anticipatory note or succession of
  notes occurring before the first barline of a
  piece, sometimes referred to as an upbeat
  figure, section or phrase or "anacrusis".
• Backbeat
• In music of duple time, the back beat refers to
  the even beats of the bar.
• Off-beat
• rhythms that emphasize the weak beats of a bar.
• The downbeat can never be the off-beat because it
  is the strongest beat in 4/4 time.

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Other usages of "beat"

• The onset of the corresponding time unit, such as
  the very moment when a metronome ticks.
• The complete time interval between two
  consecutive ticks or taps.
• In popular music, the whole sequence of
  individual beats.
• In hip hop music, the entire instrumental,
  non-vocal portion of a song.

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Time signature

• A convention used in Western musical notation to
  specify
• how many beats are in each measure, and
• what note value constitutes one beat.
• In a musical score, the time signature appears at
  the beginning of the piece, immediately following
  the key signature.

Simple example of a 3/4 time signature here
there are three quarter-notes per measure. The
"beat" most often refers to the bottom number.
Sound
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Meter

• A term that music has inherited from the rhythmic
  element of poetry, where it means
• the number of lines in a verse,
• the number of syllables in each line and
• the arrangement of those syllables as long or
  short, accented or unaccented.
• Hence in music it refers to the measurement of
  musical lines into a number of measures of
  stressed and unstressed beats, indicated in
  Western musical notation by a time signature
  (though the terminology of Western music is
  notoriously imprecise in this area).

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Meter identification

• The definition of a musical meter requires the
  identification of repeating patterns of accented
  and unaccented syllables, short and long, or a
  "pulse-group" that corresponds to the poetic
  foot.
• Normally such pulse-groups are defined by taking
  the accented pulse as the first and counting the
  pulses until the next accent.

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Tempo

• In musical terminology, tempo (Italian for time,
  movement) is the speed or pace of a given piece.
• It is a crucial element of composition, as it can
  affect the mood and difficulty of a piece.

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In terms of previous lectures

• "Once a metric hierarchy has been established,
  we, as listeners, will maintain that organization
  as long as minimal evidence is present" (Lester
  1986, 77).

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Daniel G. Mauro (2005)

• Using Music to Tap Into a Universal Neural Grammar

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The Musical Brain Model

1. Musical pieces consist of temporal sequences
   (rhythms) of frequency events (pitches) that are
   organized in serial (melody) and in parallel
   (harmony).
2. The brain processes information by means of
   temporal and frequency-based coding mechanisms
   that occur in serial and parallel neural
   pathways.
3. The acoustic ingredients with which musical
   pieces are created synchronize with rhythmic and
   frequency-based neural codes, thereby inducing a
   variety of extra-musical brain responses.
4. Music can be used as a systematic tool for
   probing these dynamic brain coding mechanisms.

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Music consists of temporally organized frequency
events

• Most forms of music can be described in terms of
  three essential components melody, harmony and
  rhythm.
• Melody consists of a horizontal sequence of
  pitches, where each individual pitch is composed
  of a fundamental frequency and a series of
  harmonic overtones.
• Harmony consists of vertical arrangements of
  pitches (chords) that support the melodic
  structure as it moves through time.
• The essential components of rhythm are meter
  (regular alternation of accented beats) and
  phrasing (temporal pattern of musical events).

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The brain organizes information in terms of
frequency codes

• Frequencies are an ubiquitous form of information
  coding throughout the brain.
• For example, stimulus intensity in various
  modalities (e.g., loudness, brightness) is
  encoded by the average spiking frequency of
  neurons.
• Oscillations in distributed neural networks are
  crucial to perceptual binding the ability of
  the brain to integrate various aspects of sensory
  input into a coherent and unified whole.
• In particular, coherent oscillations in the gamma
  frequency band (30 to 80 Hz) have been implicated
  in linking visual, olfactory and auditory
  percepts.

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The brain organizes information in terms of time
codes

• Neuronal oscillations are insufficient to explain
  cognitive functions which occur over longer time
  scales.
• Modes of cognition as diverse as language and
  spatial temporal reasoning require the sequential
  ordering and manipulation of discrete information
  over time.
• Three main types of coding mechanisms have been
  described in the literature, two of which are
  time- related
• time-of-arrival (e.g., latency codes,
  inter-neuronal synchrony codes)
• temporal pattern (e.g., complex pattern codes,
  interspike interval codes) and
• connectivity (e.g., labelled-line,
  spatial-pattern codes)

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Back to musical rhythm

• Rhythm comprises a variety of components
  including beat, pulse, accent, tempo, duration,
  meter, grouping, and phrasing.
• Of these rhythmic features, four are relevant to
  the present discussion pulse, tempo, meter,
  phrasing.
• Pulse refers to a series of regularly recurring
  beats that provides a temporal framework against
  which durations and patterns are perceived.
• Tempo is simply the repetition rate of a pulse,
  typically measured in beats per minute (bpm).
• Meter is the organization of beats into a
  cyclically repeating pattern of accents.
• Phrases are rhythmic groupings that incorporate
  varying patterns of time intervals and accents.

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Brain music

• The latter three aspects of musical rhythm relate
  to the three neural timing properties outlined
  earlier.
• In a piece of music, tempo (pulse frequency) can
  be said to correspond to the frequency of brain
  rhythms.
• Meter provides a temporal reference around which
  musical events are synchronized and thus bears a
  relationship to cortical synchrony.
• Finally, musical phrasing is similar to the
  occurrence of neuronal firing sequences that
  exhibit temporal spiking patterns.

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Next Monday

• Rhythm in music in language