exam 2 Flashcards
motor equivalence
- the output of a vocalities, can be the same even if the physical qualities of the production differ in the source and filter
Different filter types
EXPLAIN WHAT HIGH PASS, LOW PASS, BAND PASS AND BAND REJECT.
Fourier transform
utilized to change domains, creates a spectrum of all the different parts of a wave. All periodic sounds are made up of a combination of sound waves, this theorem breaks down those parts, into amplitude, phase angles, frequencies.
all periodic sounds are made of a combination of sine waves
-amplitudes vary
-phase angles vary
-frequencies vary
**creates a spectrum from the time domain waveform, “analyze a cake to learn its ingredients”
Time domain display
shows time components of a wave, amplitude on y axis, and time on x axis
a waveform represents sound directly
-air pressure changes over time
Frequency domain display
shows frequency components of a periodic sound, does not show time, y axis is amplitude, and x axis is frequency
a line spectrum shows the frequency components of a periodic sound
-description of the signal
-has F0 that are multiples of the fundamental
-has nothing between the lines, the lines represent the F0 frequencies
Spectrum of noise – white, pink, brown – how is the energy distributed?
White noise
noise consisting of all audible frequencies in equal amounts
Brown noise
low frequencies to generate a deep rumble
Pink noise
noise whose lower frequencies are proportionally higher in amplitude than higher frequencies
Spectrum vs. spectrogram
a spectra is a single snapshot in time, a line spectrum. A spectrogram is the speech overtime, lining up single slices together. Shows over time how frequency and amplitude change
Wide and narrow band spectrograms
a wide band will show clear temporal detail, and the frequency resolution is poor. In a narrow band, the frequency detail is clear, but the time resolution is poor. In a wide band we will see vertical lines, glottal air pulses!
In a narrow band we will see horizontal lines, representing the harmonics
FFT and LPC spectra – what does each show?
FFT is a fast fourier transform, shows the range of harmonics, each peak is a harmonic, less clear of the vocal tract filter, but more revealing of the source. LPC is linear predictive coding, it is a spectral envelope, good at revealing the tract or filters, and how our vocal tract is shaping the sounds from our sound source, but does not show harmonics, no sound source,
What does a typical voice FFT look like?
Individually placed lines, representing the harmonic multiples. Each peak is a harmonic, the greater space between the lines represents noise.
11. Spectral slice –
Spectral slice
how is amplitude of the frequencies shown? No individual lines, the peaks of the line are represent formants, the spectral slice represents amplitude (x-axis)
1) Is a frequency domain display
2) x-axis s frequency
3) y-axis is amplitude
A spectra represent frequency components in a wave, sine waves would only have one. Noise does not have any relationships, very close lines, all different frequencies.
How is the amplitude of frequencies shown on a spectrogram?
Shows all 3 parameters, amplitude is shown by darkened spots on the graph representing intensity
High speed filming of phonation – typical frame rate standard
VHS video uses 30 frames/ sec- works best b/c of flicker fusion rate; ultra-high speed filming uses 4000-6000 frames/ sec (not clinically practical- expensive & requires massive amounts of data)
Spectrograms of normal and hoarse voices – how do they differ?
It is easier to see the location of glottal pulses and harmonics. Hoarse voices contain more noise within them, making it harder to receive a closer estimate
Stroboscopy – how to get a frozen vs. slow motion image; live stroboscopy in clinical practice
‘frozen’ image
-flash occurs at the same point in each cycle
-slow motion image
-flashes slightly delayed in successive cycles
when these are played back you have created an animation
capitalizes on an optical illusion
- light flashes illuminate a target, each illumination is a snapshot
- paste the snapshots together in succession, voila! a movie
- video has 30 frames/sec, vocal folds may oscillate 200 times/sec timing of the flashes is crucial
a slow-motion video image of vocal fold vibration
-light rapidly flashes
-captures vocal folds in different glottic cycles in a variety of positions
-not true slow-motion, simulated
-video has 30 sec/frames
-movie is a composite of stills from different cycles
*strobe movies are made of non-adjacent sample
*true vocal fold motion is not seen
-harmonics must be steady
-flashes cannot synchronize if harmonics are erratic
-severe dysphonia precludes stroboscopy
Rigid and flexible endoscopy
RIGID
1) Uses a metal rod that contains fiber optic cables which carry light from a bright light source.
2) The light shines out of the end of the scope, downwards at an angle, towards the larynx
3) A lens on the tip of the scope brings the image back up and through the cables to a camera, which can display the larynx on a screen.
Pros: great pictures
Cons: they can’t talk at all because the thing down their throat so you don’t see much movement of the vocal folds
SLPs can get training to perform this type of exam.
FLEXIBLE
passes through the nasal cavity uses fiber optic cable/camera, a person can articulate normally, used mostly in a medical setting
- goes up the nose
Pros: not limited to just sounds but can talk normal
Cons: picture is less bright and clear
SLPs can be trained for this but only in medical environment
Electroglottograph – what the signal represents, how it compares with a mic signal visually
Microphone: very complex, repetitive
EGG: simpler, up and down once per cycle, only fundamental frequencY
what does EGG signal represent? vocal fold contact area
- signal represents vocal fold contact area
- absolute signal amplitude is meaningless
(many units have automatic gain control)
- changes in vocal fold contact are important
Two electrodes placed on the neck - over thyroid laminae
- Current passes between the electrodes
- More current when folds are together
- Less current when folds are separated
- Signal goes up and down for each cycle
Vocal perturbation (jitter, shimmer) – how to get good quality samples
-use sustained vowels
-avoid onsets and offsets
-comfortable intensity level
-record live to the computer
-compare like with like
*same vowel
*same conditions
Perturbation vs. modulation – know how they differ from each other, examples of each
perturbation
hoarse, sounding very rough
random cycle-to-cycle duration differences are called jitter
random cycle-to-cycle amplitude differences are called shimmer
jitter and shimmer co-occur, won’t find one without the other
Modulation
, rhythmic changes in the F0 and amplitude would be a tremor
Much slower than perturbation, not rapid from one cycle to the next but rather a gradual increase/decrease in f0 is spread across many cycles
AM = amplitude modulation, the rhythmic movement up and down
FM= frequency modulation, the fundamental is modulated
he nature of vocal registers – pressure needed for each, how the folds vibrate, which layers oscillate for each register
-vocal quality changes at pitch extremes
-a register is a pattern of vocal fold vibration
-the physiology changes across registers
Modal
-also called chest voice
-typical speaking voice
-also used for mid-range singing
-wide dynamic range
-whole mass of vocal fold oscillates
*TA muscle
*layers of lamina propria
*mucosal cover
Pulse register
-also called vocal fry
-voice has a pulsatile quality
-occurs at very low F0 range
-vocal folds relatively slack
-low driving pressure from lungs
-very limited pitch range
-limited loudness range
Loft register
-also called falsetto
-vocal folds are stretched tightly
-at high end of harmonics range
-cover of vocal fold oscillates medially
-little/no involvement of TA in vibration
-oscillation almost sinusoidal
Clinical evaluation of the appropriateness of pitch
-SLP can judge pitch appropriateness
-objective measure not always needed, sometimes they help
-What’s appropriate?
*gender
*age
*emotional state
Fundamental frequency variability – what the numbers mean
-low variability sounds monotone
-measuring variability
*quantifies severity
*tracks progress in treatment
Period and frequency calculation – practice this to be sure you can do it
period = 1/frequency
frequency = 1/time period
Voice changes across the lifespan
women: gradual decrease
men: teen years, larynx growing, deeper voice. rise again when older due to atrophy of the vocal fold.
Alaryngeal speech features
extremely low voice, robotic
-have no vocal fold or larynx, removed
-esphogeal sphincter vibrates for voice
Voice Source Features: Loudness
volume of voice
-objective measure
Voice Source Features: Pitch
high or low
-objective measure
Voice Source Features: Quality
breathy or tight
Voice Source Features
-fundamental frequency
-harmonics are integer multiples
-result: a whole spectrum of sound
-F0 goes up, harmonics spread
-higher harmonics progressively weaker
-harmonic spectral slope
Voice Source: Laryngeal source spectrum, Harmonic spectral slope and voice quality
- harmonic, strong bright voice
- harmonic, typical voice
- harmonic, weak thin voice
6, 12, 18 dB/octave reflects how sharply they drop off ( think of multiple colored graph)
A very weak voice would slope off rather quickly
How harmonics and their spacing will change as you change the fundamental frequency
the harmonics are multiples of the fundamental frequency
-if the fundamental frequency is 100 Hz, the harmonics will be 200 Hz, If the fundamental frequency is 220 Hz the harmonics will be 440, 660, 880 Hz, etc.
Voice source – what type of waveform is it as it leaves the larynx?
Saw tooth wave
Vocal tract transfer function
he difference between the sound that enters the vocal tract and the sound that leaves the vocal tract
-input comes from the larynx
-output comes from the lips
-resonating cavities in between determine the transfer function
What does the vocal tract filter do? Think resonance, selective amplifiction
What does it do?
resonated/altered differently
-altered size and shape of the cavities that resonate the sounds that go through the vocal tract
Source-filter interactions in therapy for Parkinson’s disease
-hypokinetic dysarthria
-weak, monotone voice
-imprecise consonant articulation
-treat loudness
*louder speech effects whole speech mechanism
*larger articulatory movements
*more consistent speech production
*more natural
*increasing amplitude, better intelligibility
