Fundamental Frequency

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Fundamental Frequency JitterLab 2
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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

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Fundamental Frequency

• F0 cycles per second
• Hz 1 cycle per second
• t (period) duration of a single cycle
• t1/ F0
• F0 1/t

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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

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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)

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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.

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Visipitch

• There are many versions of this instrument
• CSL has a Visipitch component
• The older Visipitch has a less reliable frequency
  counting system

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Visipitch Computer Interface Screen
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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

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Fundamental Frequency Contours

• Connected speech consists of varied fundamental
  frequency
• Disordered speech/ voice physiology may impair
  the clients ability to produce a normal
  intonation contour
• Contour should gradually descend

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Fundamental Frequency Contour
Identify Lowest F0 Highest F0 Describe
contour?
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Speaking Fundamental Frequency

• Best measure of the clients 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

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CV Utterance- /si/ see

• Mean SF0
• Pitch ?
• Describe contour?

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CV Utterance

• Could this utterance be used to describe this
  speakers vocal frequency use?
• Why? Why not?
• Length
• Pitch
• Loudness
• What might you use to describe vocal frequency
  use?

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Frequency Trace Rainbow Passage

• Extract 3rd sentence
• Highest F0
• Lowest F0
• Mean S F0
• Pitch ?

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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

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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

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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

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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

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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
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Calculating Jitter

• Mean jitter factor difference between sequential
  frequencies/ mean frequency

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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

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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

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Types of Shimmer

• Amplitude Perturbation Quotient
• Analogous to RAP, the amplitude perturbation
  quotient (APQ) attempts to desensitize long-term
  amplitude changes APQ uses 11 point averaging
  (average of 11 cycles). The average amplitude
  differences I divided by the mean period

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Calculating Shimmer