Fricatives and Affricates

1
Fricatives and Affricates

• We will be looking at acoustic cues in terms of
• Manner
• Place
• voicing

2
Fricatives and Affricates (manner)

• Manner
• Different from stops in that fricatives are
  continuants.
• Noisy aperiodic component

3
Fricatives and Affricates (place)

• Place
• Absolute intensity of fricative.
• Spectral frequency

4
Fricatives and Affricates (place)

• Center frequencies will change depending upon
  vowel context (adaptation)
• Other fricatives have more spectral spread and is
  difficult to identify by spectral frequency
  alone.
• F2 transition points roughly to center frequency.
  e.g., the F2 transition for /s/ points to about
  4000 Hz. These transitions are important for
  perception of other fricatives which have weak
  center frequencies.
• Affricates contain aspects of both stops and
  fricatives.

5
Fricatives and Affricates (place)
6
Suprasegmentals

• Suprasegmental perception is poorly understood
  when compared to suprasegmental production.

7
Suprasegmentals (intonation)

• Intonation
• Ability to changes in intonation is dependent
  upon ability to track pitch.
• Physiological mechanisms for decoding are unknown
  be probably in Wernikes area.

8
Suprasegmentals (intonation)
9
Suprasegmentals (intonation)

• System analyzes speakers harmonic structure of
  speech and then can determine fo and track pitch
  and fo changes by analyzing change in harmonics
  (e.g., hearing aids and telephones).

10
Suprasegmentals (stress juncture)

• Stress is determined by changes in pitch,
  loudness and duration.
• Juncture is determined by silent periods, vowel
  duration or other features such as voicing or
  aspiration.
• Physiological mechanisms for loudness and
  duration are also thought to be in temporal lobe
  of cortex.

11
Context

• Perception of allophones, phonemes, syllables,
  words or even phrases are dependent upon context.
  (e.g., spin test)
• Being able to identify context is important for
  speech perception, especially for people with
  hearing loss.

12
Categorical Perception

• Refers to ability of a listener to discriminate
  on phoneme or perceptual cue from another based
  on subtle differences in the acoustic cues.
• Categorical boundaries are an important part of
  categorical perception. Provide examples.
• Study by Liberman (1957) shows how changes in F2
  formant frequency can influence perception. They
  looked at ability to identify phonemes and to
  discriminate between phonemes.

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Categorical Perception

• Describe study

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Categorical Perception

• Similar studies have been used to study virtually
  every known acoustic cue.
• People with cochlear hearing loss interferes with
  categorical perception. What are implications?

15
Categorical Perception

• Effects of Language
• Effects of Instinct
• Best guess is both play an important role.

16
Hearing Loss and Speech Perception

• Review Audiogram
• Effect on speech dynamics and specific phonemes
• Effect on suprasegmentals
• Effect on categorical perception

17
Summary