physical acoustics
what is a pressure wave?
after a force is applied, air molecules move back and forth around the rest position due to elasticity and inertia to propagate through air
define resonance
objects vibrate with maximum energy at their natural frequency
Which feature of the glottal source is responsible for the fundamental frequency?
periodic signal
What is the source of vowels?
vocal fold vibration generating a pressure wave
When measuring pressure waves, what is the spatial and temporal measurement system we use?
we use the wavelength for spatial measurement and the waveform for temporal
periodic or aperiodic: this complex event can be broken down into harmonics from the fundamental frequency
periodic
For a tube closed at one end, what rule do we say matches it's pressure condition?
quarter of a wavelength rule
What term do we use to describe the width and length of the glottis as a function of time?
glottal area (Ag)
How are the source and the filter related in source-filter theory?
They are independent of each other
What happens to resonant frequency when we increase vs decrease the size of the bowl in the helmholtz resonator?
if the bowl increases, frequency decreases and when the bowl decreases, frequency increases
find the time for a frequency of 200 Hz.
5 ms or 0.005 seconds
What are the 4 factors related to energy loss and how do 3 of them relate to human speech?
friction (air molecules rubbing against each other), absorption (vocal tissue absorbing air molecules), radiation (loss of energy from the nose and lips), and gravity
what does the shape of the waveform reflect?
How quickly the vocal folds are coming together
What is a formant and which ones do we care about for vowel specification?
A region or envelope of high energy in the spectrum as a result of harmonics. We care about F1, F2, and F3.
What happens to F1 when you move from /æ/ to /i/
F1 decreases
If there is an increase in frequency, how do we hear that perceptually?
there is an increase in pitch
In the Helmholtz resonator, how will frequency be affected if we increase mass?
there will be a decrease in frequency (lengthening the neck)
What happens to voice quality if there the vocal folds come together too rapidly?
less than normal energy loss in the system leading to an effortful or strained voice quality
What are the 3 factors of perturbation theory and what is their relationship to their formant?
tongue height (inversely related to F1), tongue advancement (directly related to F2), and lip configuration (rounded lips decrease all frequencies but has the most affect on F2)
What are the 3 factors that affect the glottal source in the waveform and / or spectrum?
periodic signal, shape of the glottis, and ratio of time open / close
What is the x and y axis for a waveform vs a spectrum?
waveform has time as the x and y as amplitude, while the spectrum has x as frequency and y as amplitude
Where do we measure bandwidth on the graph and how do we know if it's lightly or heavily damped?
At the 3dB down point. Heavily damped systems have a wider bandwidth, while lightly damped systems have a narrower one.
If the glottal source spectrum shows a higher than normal tilt, what does that tell us about the shape of the vocal folds and voice quality?
The vocal folds are coming together too slowly, leading to a weak and breathy voice
When we make a constriction at region of highest pressure, how does that affect resonant frequency, and where is the highest pressure in relation to the vocal tract?
The resonant frequency increases. The region of highest pressure is typically at the glottis.
What happens to resonant frequency when you move from low to high pressure?
The resonant frequency increases.