Speech Perception 1

Fricatives and Affricates

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

Speech Perception 2

Fricatives and Affricates (manner)

• Manner– Different from stops in that fricatives are continuants.

– Noisy aperiodic component

Speech Perception 3

Fricatives and Affricates (place)

• Place– Absolute intensity of fricative.– Spectral frequency

Speech Perception 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.

Speech Perception 5

Fricatives and Affricates (place)

Speech Perception 6

Suprasegmentals

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

Speech Perception 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 Wernike’s area.

Speech Perception 8

Suprasegmentals (intonation)

Speech Perception 9

Suprasegmentals (intonation)

• System analyzes speaker’s 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).

Speech Perception 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.

Speech Perception 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.

Speech Perception 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.

Speech Perception 13

Categorical Perception• Describe study

Speech Perception 14

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?

Speech Perception 15

Categorical Perception

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

Speech Perception 16

Hearing Loss and Speech Perception

• Review Audiogram• Effect on speech dynamics and specific phonemes

• Effect on suprasegmentals• Effect on categorical perception

Speech Perception 17

Summary