Resonance Flashcards
what are the two different types of vibration?
free and forced
when does free vibration occur?
free vibration occurs when an object vibrates without interference
How is the rate of vibration determined?
mass, tension, length
what is resonant frequency?
the rate at which an object vibrates freely
also known as natural frequency
when does forced vibration occur?
when the vibrations of one object cause another to vibrate if their RFs are close enough
ex) tacoma narrows bridge
ex) high note shattering glass
explain the shattered glass example of forced vibration.
the frequency of the note and the glass match. because they are vibrating at the same rate, constructive interference happens and causes the amplitude to increase
what is applied/driving frequency?
the vibration of the original source
ex) singer
what is a resonator?
the object that is forced into vibration
ex) glass
name some effects of resonance
- make walls buzz
- make speech possible
name the 2 types of resonators
mechanical and acoustic
what is a mechanical resonator?
does not contain a body of air
ex) tuning fork, wall
what is an acoustic resonator
container filled with air
ex) vocal tract, ear canal, mirror, tube
what is the relationship between mass and resonant frequency
the bigger an object, the lower is its frequency
how do acoustic resonators act as filters in speech?
they exclude certain frequencies while allowing others to pass
this is based on constructive and destructive interference.
which frequencies will a resonator amplify?
frequencies at or close to its resonant/ natural frequency
which frequencies will a resonator damp/attenuate?
frequencies that are far from its RF/NF
what is bandwidth?
the range of frequencies that a resonator will transmit/amplify/respond to
A resonance curve shows…
the vibratory response of a resonator to any applied frequency (bandwidth)
Some other names for a resonance curve are
transfer function, input-output graph
Does a resonance curve show sound
NO it shows the frequency response of a resonator
Center Frequency (fc)
Natural frequency-the resonant frequency with the greatest response from the system
Upper cutoff frequency (Fuc)
frequency above the Fc where the resonator does not respond
Lower cutoff frequency (Flc)
frequency below the Fc where the resonator does not respond
low pass filter
all lower frequencies are transmitted
high pass filter
all higher frequencies are transmitted
band pass filter
all frequencies within a certain bandwidth are transmitted and those outside are damped
band stop filter
higher and lower freqs. pass but not those within
damps freqs. within bandwidth
happens during speech
What type of filter is the VT?
band pass filter
which cavities is the VT comprised of?
pharynx,oral, and nasal
describe the VT as a resonator
VT is a tube which is open at one end (lips) and closed at the other (VF must be closed in order to vibrate)
Quarter wave resonator
only one quarter of the wave fits into the tube at any time
has multiple resonant frequencies, multiple bandwidths
what are resonant frequencies of the VT called?
formants
why is the VT called a variable resonator?
because it can assume different shapes (through articulators)
Different shapes result in..
different formant frequencies
what does the sound filter theory of vowel production explain?
it explains how the sound prodouced at the larynx is modified by changing VT resonances to create different vowels
source function
origin of sound, VF vibration
doesn’t sound like anything but buzzing
transfer function
VT resonance response to diff frequencies shown on a resonance curve
output function
the sound exiting the oral or nasal cavity
which vowel is the SFT based on?
schwa
