Vibrato

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:

* 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

--> 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.

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