Sound Production and Timbre Perception
Chen, Elements of the Human Voice
Elements of Timbre
Mouth tone/Larynx Tone
Initial Sound Production
The Decaying Elementary Wave
Relevancy of Formants
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Superposition and vowels
Dynamic Acoustic Process
Sound produced by glottal closing
Hixon, Acoustic Theory of Vowel Production
Input Signal Generation
Vocal Tract as a Tube
Determination of Acoustic Properties
Dynamic Aspects of Resonance
Theoretical Confirmation
Vg/vocal fold vibration as acoustics of the source
Inverse Filtering as a means to study
Closing of folds is quicker than opening
"Relative amplitudes of the frequency components that decrease systematically as frequency increases" pg. 293
"...the vocal tract resonating like a tube closed at one end, multiple peaks are expected in the resonance curve" pg.291-292
"At the vocal fold boundary of the vocal tract, there is, for an instant, no airflow..." pg. 297
"Input signal is a complex periodic waveform whose spectrum consists of a consecutive integer series of harmonics at whole-number multiples of the F0"
"Vocal tract resonances are excited each time the vibrating vocal folds snap together" Pg. 298
Responses to excitation can are damped oscillations at resonant frequencies
Vocal Tract Configurations as a dynamic variable of sound shaping
Different areas of the tract have different capabilities in shaping
"Area function of the vocal tract" pg. 301
Mass/Compliance factors of tissue flexibility
Source/Filter Theory
Areas of dampening and areas of multiplication
Human ability to control constriction/relaxation of vocal tract
Constrictions create area of higher pressure
"The resonances of the unconstricted tube are reference frequencies, and the frequencies of constricted tubes can be regarded as deviations from these reference values." pg. 310
Narrower the constriction, the higher the velocity of the air
Perturbation Theory - "How the resonances of a tube are changed when the cross-sectional dimensions of the tube are pertubed, or constricted" Page 313
three-parameter model of vowel articualtion
Tongue Height
Tongue Advancement
Configuration of the Lips
Stevens and House Rules
"...allow a practitioner to examine an acoustic record of an utterance, locate the formant frequencies, and infer the likely vocal tract configuration(s) that produced those formants." Pg. 232
Agreement with Human Points
Plomp Disseration, Experiments on Tone Perception
Historical Exploration of Theories on Timbral Perception
Hypothesis: Pitch of tone is based on period of sound waves
Counter: Assumption that ear has two pitch-detecting mechanisms: periodicity/low frequency, maximal basilar stimulation/high frequency
"Hypothesis V. The distribution of stimulation along the basilar membrane determines timbre." pg. 131
Refutation Substantiation: Periodicity theory does not provide any attribute to hearing that is analogous to localization of stimulus on skin
"The different vowels are characterized by strong harmonics in some fixed frequency bands, known as the formants, with centre frequencies varying form vowel to vowel" Page. 131
Pitch is correlated with periodicity; brightness with frequency. pg. 132
Simple vs. Complex Tones
"For simple tones, a one-dimensional relation exists between frequency and timbre: low tones sound dull and high tones sound bright" pg. 133
"...parameter brightness holds only in a strict sense for complex tones when most of their energy is concentrated in a limited frequency band; otherwise we need more than one category for distinguishing among different timbres." pg. 133
Plomp, The Intelligent Ear
"The ear distinguishes between frequency components originating from different sound sources, as opposed to components from the same source" pg. 12
This process involves both deconstruction (analysis) and a reconstruction (synthesis)
"...the ear separates, in one way or another, these sounds in terms of their period duration as well as their waveform." pg. 13
Complex vs. Simple tones
"We may conclude that the limit of listeners' ability to hear out the harmonics of a complex tone agrees rather well with the ear's frequency-resolving power" pg. 17
Dependent on listener's being directed in the right way
Experiments on Perception
Use of a dissimilarity matrix in triadic comparisons effectively "represent spectral differences between different sounds as well as configurations representing their perceptual dissimilarities" pg. 22
Simple: "For the extreme case of a sinusoidal tone without harmonics, the tone's frequency as its single variable determines pitch as well as timbre" pg. 23
Low-pitched sinusoidal/dull; High-pitched sinusoidal/sharp
dull -> strong fundamental; sharp -> strong higher harmonics