Vibrato

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literature review

1. Perceptual Evaluation of Vibrato Models

Vincent Verfaille, Catherine Guastavino, Philippe Depalle
Proceedings of the Conference on Interdisciplinary Musicology (CIM05)
  • spectral envelope modulation
  • frequency-dependent hysteresis behavior
  • test: preference for sounds with modulated spectral envelope
  • offers great literature review & background info on vibrato pitch, rate, extent, shape, and temporal evolution
  • provides equations for modeling FM, AM, SEM pulsations
  • vibrato is made of at least one of these three kind of modulations:
  1. amplitude modulation (predominant in wind and brass instr)
  2. frequency modulation (predominant in voice and string instr)
  3. spectral envelope modulation and hysteresis (existing in wind, brass, voice)
  • Questions & thoughts:
* How much of the analysis is instrument-specific, and how much is it performer/ context/ style-specific?
* It'd be interesting to see a more music-passage specific (higher level) analysis as opposed to instrument-specific modelling

2. An Investigation of Vocal Vibrato for Synthesis

Robert Maher, James Beauchamp
Applied Acoustics 30 (1990) 219-245
  • focuses on vocal vibrato & presents a new panned-wavetable synthesis method
  • role of spectrum modulation
  • findings: "Inclusion of typical random fluctuations of vibrato rate, vibrato depth, and nominal sung frequency resulted in no quality preference over examples with constant values. Inclusion of vibrato-induced spectrum modulation resulted in a substantial improvement over examples having constant spectra."

3. Synthesis of Vibrato Singing

Yoram Meron and Keikichi Hirose
2000 IEEE International Conference on Acoustics
  • matches the phase of the vibrato in the original unit (used for synthesis in the source database) with the vibarto phase of the synthesized (target) vibrato sound.
  • useful section: 3.1 Vibrato detection
  1. rate between 4.5 adn 7.0 Hz
  2. modulation depth between 4% and 15%
  3. extracted pitch - interpolated extrme points, compare to threshold
--> sequence of 5+ extreme points which pass all these tests are marked as vibrato anchor points

4. Automatic detection of vibrato in monophonic music

Hee-Suk Pang, Doe-Hyun Yoon
Pattern Recognition 38 (2005) 1135-1138
  • method that automatically detects vibrato using (1) vibrato rate, (2) extent, and (3) intonation
  • potential applications: wav-to-midi conversion
  • uses maximum likelihood estimation (understand this..?)
  • vibrato existence as product of (1) vibrato rate and (2) normalized vibrato extent probabilities
  • Questions & thoughts:
  • extend to polyphonic music with a vibrato solo-line? polyphonic music with overall vibrato quality?
  • mentions how the recommended coefficient values can (should) be modified depending on musical style... It'd be nice to know how style affects these.

Where to go from here

  • Goals
    • take a simple monophonic wav file and try to detect locations where vibrato is used
    • characterize parameters of vibratos for different style/ context
    • ultimately: try to apply expressive nuances/ vibratos to scores and MIDI files, etc. Try to impart characteristics of "style"
  • Approach
    • avoid being instrument-specific
    • make it easily applicable to computer-generated sound, ensembles
    • aim for a higher level characterization