Pitch Perception. Roger Shepard

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1 Pitch Perception Roger Shepard

2 Pitch Perception Ecological signals are complex not simple sine tones and not always periodic. Just noticeable difference (Fechner) JND, is the minimal physical change detectable by a human. Just noticeable difference has been used as a measurement of psychological levels of stimuli. Stevens assessed JND agains direct subjective experience Quite different to JND (represents difference from subject to subject baseline). Neither approach is accurate

3 Pitch Perception In Mel scale - subjective (figure 13.1) Keyboard range adjusted to Mel scale. Mel = unit of pitch, equal to one-thousandth of the pitch of a simple tone whose frequency is 1000 hertz and whose loudness is 40 decibels above a listener's threshold. Closer in lower octaves, further apart in upper octaves. Mels Vs Log Freq - not linear Mel constant Perceived distance = log frequency scale. i.e.the Octave has the same reach = pitch doubles On piano keyboard not on other instruments necessarily.

4 Pitch Perception Figure 13.2 graph shows how interval size changes across Mel scale Hz How does this relate to the Fletcher-Munson We are more sensitive to central frequencies so therefore our acuity is higher.

5 Pitch Perception Attneave and Olson (1971) also supported a logarithmic scale (see figure 13.3) Attneave and Olson (1971) also argued - Pitch and melody are a Morphophonic Medium relates to patterns of pitch Pitch & time are crucial. Timbre, spatialization and loudness are secondary.? Because they were using melodies compositional approach pitch over time

6 Pitch Perception Kubovy (1981) Dispensable versus Indispensable. Stereo recordings use this phenomena. The signal appears to be in front of you. Pitch is indispensable, space is dispensable Depends on what you are listing for lion

7 Pitch Perception Height Drobisch -- tones -- helix Octaves above and below each other are associated with pitch height Roger Shepherd, see figure 13.6 Chroma equals the distance relationship. Chroma i.e. Imagine on 2D plane - 5 steps away but without the height represented by the helix.

8 Pitch Perception Dowling, Hollombe (1977) and Deutsch experimented with scrambled melodies and found that our perception of melody critically depends on high as well as Chroma. See figure A 4D representation equals Chroma and Height and the dimensions of the circle for the cycle of fifths. Note "most musically sophisticated subjects responded most to the cycle of 5ths"? Training, cultural background, jazz or classical?

9 Pitch Perception Figure 13.2, melodic space. Reference to previous paper. Korte s 3rd law - large steps take more time to process melodies seem to fall apart if large steps are included. See later discussion about analysis of pitch steps in melodies.? Vectors of change Contour

10 Pitch Perception Psychologists are not necessarily highly trained musicians. Musicians are trained to perceive "shape of phrase" and "harmonic destination". Such training would lead to long-term perception of vectors of change as distinct from intervals. These are also memorized when learning a piece so become subconscious

11 Memory Chapter 17 memory. Hippocampus and pre-frontal cortex are associated with memory Likely to be distributed muscle memory. - Procedural memory - doing things Iconic memory - images Echoic memory - sound Working memory - conversation - doing things now Long term memory - life

12 Memory Iconic memory may be experienced as a residual image on the visual cortex. Echoic memory - residual sound awareness - Atkinson & Shiffrin (1986) Both deal with a sensory buffer. Immediate sensory memories are stored in a sensory buffer. Contextual constraints are associated with chunking to establish patterns to make composite elements which expands the capacity of the sensory buffer. An example of this would be a musical chord, made up of three or more elements - perceived as one object. It is argued that the capacity of the sensory memory is 5 to 9 elements (Miller 1956). The Working memory (sensory buffer) is used for current functions such as conversation (Alan Badalley 1990)

13 Memory Long-term memory contains the memories about life etc - may also play a role in musical cognition in terms of references to past musical experience, and association of musical experiences with life experience. For instance you heard that song for the first time whilst on holiday in the Caribbean.

14 Memory Tulving (1985) Episodic memory events such as birthdays holidays et cetera Semantic memory linked or associated used for facts Procedural memory tie your shoes, make coffee etc Abstract representation car a class of objects, not a specific car. You reduce - (irreducable idiostructural) classes of objects reduce cognitive load - ie you don't have to remember ever car Gist of an experience event conversation - not the specifics.

15 Memory Musical perception Music has seven perceptual attributes pitch, rhythm, tempo, contour, tempo, loudness. Melody = auditory object that is maintain when attributes are altered slightly. Melody - For instance you can alter the pitch, tempo, timbre, loudness, spatial location, and reverberation, with small variations in rhythm acceptable and with the contour change rarely acceptable.

16 Memory Contour IS Critical Memory = abstract representation of pitch invariance (Contour)? Page 215 "at first, the idea of contour being an important attribute of melody seems counterintuitive." - Clearly not a train classical or jazz musician Shown in infants and even animals.

17 Memory Amusia - see Oliver Sacks. There are interesting cases when after a stroke, the patient cannot talk, but can sing to communicate. This illustrates that different parts of the brain are engaged for speaking communication and a combination of text and melody in the production of song.

18 Memory Daniel Levitin long term memory includes abstract pitch representation of songs - see experiments - subjects singing a favorite rock song Also shows that absolute and relative information is held in the long term memory. Subjects were within the just noticeable difference range of 6.2 to 8% without any priming. This indicates relative encoding of relationships And absolute encoding of sensory features.

19 Perceptual fusion + auditory perception. John Chowning

20 Perceptual fusion + auditory perception. Periodic waveforms quasi-periodic waveforms. Auditory perception is extraordinarily sensitive to micro changes in quasi-periodic waveforms. Remember fourth tone pulse had a reverse phase and was distinct Non-linearity equals natural of nature - What we used to Variations in breath, pressure etc

21 Perceptual fusion + auditory perception. See Figure 20.2 sung soprano voice. Phase 1 fundamental Phase 2 harmonics added unrecognizable and voice Phase 3 random pitch variation and vibrato added fusing harmonics to fundamental Commonality invariance are key to fusion leads to stream segregation Key to: source identification source segregation.

22 Perceptual fusion + auditory perception. Experiment - singers close and far away Consider paper two perception of mechanical attributes referred to as spectral brightness indicates more energy used in excitation of source. More effort for faraway signal Perceived as more energy used in production of sound Relationship of timbre and intensity are critical to identification of perceptual distance. Also consider reverberation energy Early reflections Secondary and main signal. Coloration from room is clearly stronger when signal source is more distant.

23 Perceptual fusion + auditory perception. Loudness Loudness constancy - Like visual constancy - we can calculate the size of an object at differing distances Not like perspective in vision as loudness can change suddenly and non-linearly.

Music 175: Pitch II. Tamara Smyth, Department of Music, University of California, San Diego (UCSD) June 2, 2015

Music 175: Pitch II. Tamara Smyth, Department of Music, University of California, San Diego (UCSD) June 2, 2015 Music 175: Pitch II Tamara Smyth, trsmyth@ucsd.edu Department of Music, University of California, San Diego (UCSD) June 2, 2015 1 Quantifying Pitch Logarithms We have seen several times so far that what