Fundamental Frequency & Jitter
Lab 2
Fundamental Frequency
• Pitch is the perceptual correlate of F0
• Perception is not equivalent to
measurement:
– Pitch= intensity, spectral characteristics
– F0 is determined by rate of vocal fold vibration
• Fundamental frequency is often used in
voice assessment
Fundamental Frequency
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F0= cycles per second
Hz= 1 cycle per second
t (period)= duration of a single cycle
t=1/ F0
F0 =1/t
Fundamental Frequency
• Instrumentation– Visipitch II, CSL, MDVP, Oscilloscope
– All instruments are not equal
– Some instruments allow you to choose the sample
section you wish to analyze
• Example of collecting F0 from each instrument
Maximum Phonational
Frequency Range (MPFR)
• MPFR= Lowest sustainable model-register tone
to the highest falsetto-register tone
• All frequencies not used in connected speech
• MPFR may indicate a vocal pathology
– reflection of reduced vocal flexibility and adjustability
• Example- Two oscillograms (High and low)
Normative Data: F0
• MPFR- Baken Text (Pg. 185-190)
– *look at other sources listed under table- p.188
• Speaking fundamental frequency- Baken
Text (Pg. 186)
– *Difference between speaking F0 (SF0) using
connected speech, and F0 obtained using a
sustained vowel.
– *Look in your voice text (Colton & Casper) for
sustained vowel F0.
Visipitch
• There are many versions of this instrument
• CSL has a Visipitch component
• The older Visipitch has a less reliable
frequency counting system
Visipitch: Computer Interface Screen
Dysphonic Speakers
• CSL- Voice Disordered database
• Can take disordered voice samples from
CD-Rom
• Analyze them as you would your own
sample
• Use manual for description of patient
Fundamental Frequency Contours
• Connected speech consists of varied
fundamental frequency
• Disordered speech/ voice physiology may
impair the client’s ability to produce a
normal intonation contour
• Contour should gradually descend
Fundamental Frequency Contour:
Identify:
*Lowest F0
*Highest F0
*Describe contour?
Speaking Fundamental Frequency
• Best measure of the client’s phonatory
system use (mean speaking F0 (SF0))
– Mean SF0 = the average of frequencies used in
an utterance
• Perceived as an abnormal habitual pitch
– Pitch  = standard deviation
• Measure of how much F0 varies in an utterance
• Abnormally high or low pitch  indicates speaker
does not adjust phonation correctly when speaking
• Perceived as “monopitch” or “tremulous”
CV Utterance- /si/ “see”
• Mean SF0
• Pitch 
• Describe contour?
CV Utterance
• Could this utterance be used to describe this
speaker’s vocal frequency use?
• Why? Why not?
– Length
– Pitch
– Loudness
• What might you use to describe vocal
frequency use?
Frequency Trace: “Rainbow Passage”
• Extract 3rd sentence
• Highest F0
• Lowest F0
• Mean S F0
• Pitch 
Vocal Jitter: F0 Perturbation
• Frequency of a speakers voice will vary from one cycle
to the next
• The random period variability= frequency perturbation
or vocal jitter
• Vocal jitter increases in voice disorder & is responsible
for hoarse, harsh or rough voice quality
• Jitter is a measurement of vocal stability
• Normal voices are usually less than 1% frequency
variability
Types of Jitter Measurement
• Mean Absolute Jitter:
– mean absolute difference between sequential vocal periods
measured during a sustained phonation (measured in seconds or
milliseconds)
• Mean Percent Jitter & Jitter Ratio:
– taking the mean absolute jitter & dividing it by the mean vocal
period used during the phonation, the proportion is then multiplied
by 100 to get a %age; if the proportion is multiplied by 1000 it is
called jitter ratio and is dimensionless
Types of Jitter Measurement
• Relative Average Perturbation (RAP):
– Relative jitter measure that attempts to reduce the
effects of long term F0 changes, such as slowly rising or
falling pitch.
– Compares average of three cycles to given period.
Averages 3 periods or cycles and compares it to the
given period. The average difference is then divided by
the mean period. If multiplied by 100 then it is called
RAP%
Types of Jitter Measurement
• Mean Jitter Factor:
– mean absolute difference between sequential
vocal frequencies divided by the mean
frequency of phonation, this proportion is then
multiplied by 100
• Frequency equivalent of mean percent jitter
Calculating Jitter
Time (ms)
Period (t) in ms
Jitter in ms
Mean period
Mean F0
Mean absolute jitter
Mean % jitter=
Mean absolute. Jitter/mean period x 100
Calculating Jitter
• Mean jitter factor= difference between
sequential frequencies/ mean frequency
Vocal Shimmer: Amplitude
Perturbation
• Same as frequency perturbation, but
analogous to amplitude
• Amplitude perturbation or vocal shimmer
serves as an index of vocal stability
• Excessive shimmer= perception of
hoarseness
• A mean cycle-to-cycle amplitude difference
of 0.7 dB or less variation or less than 7%
of mean amplitude is normal
Types of Shimmer
• Mean Shimmer in Decibels:
– mean absolute dB (SPL) difference between
sequential vocal amplitudes measured during a
sustained phonation
• Mean Shimmer in Percent:
– mean absolute cycle-to-cycle difference in
vocal amplitude divided by the mean amplitude
then multiplied by 100 to yield a % age
Types of Shimmer
• Amplitude Perturbation Quotient:
– Analogous to RAP, the amplitude perturbation
quotient (APQ) attempts to desensitize longterm amplitude changes; APQ uses 11 point
averaging (average of 11 cycles). The average
amplitude differences I divided by the mean
period
Calculating Shimmer