CDO 463 6 Vowels
Card Set Information
CDO 463 6 Vowels
Speech Acoustics Vowel
Speech acoustic vowels
Vocal Tract Filter
Acoustic theory of speech production
Speech results from a combination of sound source(s) and the filtering provided by the vocal tract.
An example of a forced vibration.
Acoustic Properties of the Vocal Tract
Uniform Tube Model 1
Length varies with age and gender: males>females>children
as vocal tract length increases, resonant frequencies decrease.
Males: L = 17 cm; F1 = c/4L = 34000/68 = 500 Hz, F2 = 1500 Hz
Females: L = 14 cm; F1 = c/4L = 34000/56 = 607 Hz, F2 = 1821 Hz
vocal tract is highly damped. Low amplitude of force vibration, but broad range of frequencies resonated.
Resonance Curve (frequency response)
Combination of the resonance curves for each natural frequency
Peaks: regions of resonance
Valleys: regions of damping
Vocal Tract Damping Characteristics
low amplitude of forced vibration
broad range of frequencies resonated.
region of frequency resonated by the vocal tract due to its shape and corresponding frequency response
first two most important for vowel recognition
Relationship between formants (filter) and harmonics (source)
Formant: Contains one or more harmonics from the voice (source)
vowel sounds produced with a relatively stable placement of the articulators.
Tongue Height: high, mid, low
Tongue Advancement: front, central, back
Lip Configuration: rounded, unrounded, spread
Tension: tense, lax
vowel sounds produced with changing articulation
tongue moves from low to high (more constricted)
compare /i/ and /æ/
tongue moves front-back
compare /C/ and /æ/
lip moves from rounded-unrounded (neutral)-spread
duration: tense vowels are longer than lax
f0: higher for tense than lax vowels
formant frequencies: small differences due to the tongue positioned slightly higher for tense vowels than lax vowels
Place cursor into the middle of each band
Linear Predictive Coding (LPC) Spectrum
Special mathematical procedure for determining formants
Place cursor into the middle of each peak
Automatic analysis (LPC)
Use of software programs to automatically measure formant frequencies.
Generates a wide-band spectrogram and then automatically draws a tracing of the formants based on the LPC analysis