Acoustics
the science of the production, propagation, and perception of soundwaves
Sound
a disturbance of particles in a medium, sometimes air
soundwave
a series of compression and rarefaction in a medium
Compression
a positive pressure or bunching molecules in a medium
Frequency
the number of compressions or rarefaction cycles that occur each second within a soundwave
Wavelength
the distance between adjacent compressions
Amplitude
the magnitude of the compressions within a soundwave
spectral envelope
all frequencies present in a complex soundwave
Resonance
the addition of supplemental vibrations to enrich and intensify sound
• A constriction in the front
vocal tract lowers F1 and raises F2
A constriction in the back of the vocal tract
raises F1 and lowers F2
All formant frequencies lower uniformly when the vocal tract is
lengthened
All formant frequencies rise uniformly when the vocal tract is
shortened
All formant frequencies lower uniformly (2)
with lip rounding and increase
with lip spreading
• An increased mouth opening (dropping the jaw)
raises F1
If F1 is tuned near to H1
Inertance becomes insynch with the vibration
• Threshold of phonation pressure lowers
• Phonation occurs with less effort
Singer’s Formant
ratio of 6:1 w/collar of larynx to length of vocal tract. Average is 2800 Hz
Closes the jaw does what to F1
Lowers
opening or dropping the jaw does what to F1?
Raises it
Perception of Volume
– loudness is subjective
– higher the pitch, higher the intensity
Traits of Lower frequencies
-larger wavelengths
-lend to bend around objects
Which formants determine what vowel we hear?
F1 & F2
Null Points
points in tube when compression or rarefaction pressure is 0
Compression (in phase)
Compression moves to a narrow medium
Rarefaction (Out of phase)
Compression moves to a wider tube
2 types of Resonance
1.) forced–direct connection (piano)
2.) free–flute
voice is a combo of both
Partial
non-whole number multiples
4 characteristics
1. Frequency 2. Amplitude 3. Spectral Envelope/ tone color 4. Duration
Rarefaction
negative Pressure
Basics of Vocal tract innertance
a tube w/a column of air in it
-vocal tract shape can course inertance to be in or out of sync w/vocal folds, thereby affecting phonation in sync=aids out sync = ceases
An increases mouth opening (dropping the jaw)
raises F1
All Formant frequencies lower uniformly when
the vocal tract is lengthened or w/lip rounding
All Formant frequencies rise uniformly when
the vocal tract is shortened or w/lip rounding
Source Filter Theory
“The sound source is the time-varying glottal airflow & the filter is the vocal tract. Whereas the glottis produces a sound of many frequencies, the vocal tract selects (filters) a subset of these frequencies for radiation from the mouth
Formant
– a resonance of the vocal tract
– a spectral maximum frequency
– a peak in a filter model (LPC or LTA)