Acoustic Cues Flashcards Preview

Speech Science > Acoustic Cues > Flashcards

Flashcards in Acoustic Cues Deck (16)
Loading flashcards...
1

Listener Cues

Listeners use more than acoustic information

Knowledge of the speaking situation
Knowledge of the speaker
Visual cues obtained by watching the face and gestures of the speaker
Nonacoustic cues are important

Person perceiving speech is aware of the message – not the individual speech sounds or patterns that make up the message.

2

Speech Perception

The auditory system is especially tuned for speech

We are best at hearing speech sounds

Infants categorize sounds of speech into groups similar to the distinctive groups that are used in many languages

It’s a specialized aspect of a general human ability – to seek and recognize patterns

3

Speech Development

Begins during the prenatal period

Learns the melody of speech and sounds of language in 3rd trimester

Newborns respond to their mother’s voice over an unfamiliar voice

Prefer passages read during the last trimester over novel passage

Preference for maternal reading over an unfamiliar female reading

4

Speech Perception

Speech sounds are rarely produced in isolation; They overlap and influence one another

For perception – speech sounds often are not discrete and separable – as are letters in written words; The listener must use context to decode the acoustic message

Listeners often perceive speech sounds by using the acoustic information in neighboring segments

There is evidence that speech perception is a somewhat specialized function in the brain

5

Vowel Perception

Vowels – most perceptually salient sounds
Phonated and high in intensity
The vocal tract is relatively open
Long in duration

The most important acoustic cues to the perception of vowels are in the frequencies and patterning of the speaker’s formants

Listeners usually required only the first and second formants to identify a vowel

However, formant frequency values are not reliable cues to vowel identification because
-variety of vocal tract sizes producing the formants
-Formant frequencies are affected by context and rate of articulation
-With increased rate of speech, vowels are often neutralized – like the schwa
-At normal conversational rates the articulators are in continual motion and the peaks of resonance are continually changing

6

Vowel Identification

Use patterns rather than the actual values of formant frequencies

Example /i/ - first formant is very low and 2nd formant is very high.

The formant frequencies will be different from speaker to speaker, the size of the gap will be great – same for the vowels /a/ and /u/

7

Semivowel Identification

/w/, /j/, /r/, /l/ - voiced and characterized by changing formant frequencies called transitions

These provide acoustic cues to their identification

Only 2 formants are needed to recognize the /w/ and /j/ sounds

3 formants are needed for the /r/ and /l/ sounds

8

Transitions

occur when a vowel precedes or follows a consonant, which reflects changes in resonance as the vocal tract shape changes to or from the more constricted consonant position

9

Nasal Identification

Formant transitions of vowels preceding and following nasals were effective cues to the identity of the nasals as a class

This change from an orally produced vowel to a nasal includes 2 important features

1. a weakening of intensity serves as a cue to nasal manner
2. addition of a resonance below 500 Hz is called the nasal murmur

Formant transitions to and from /m/ are the lowest in frequency and shortest in duration

To and from /n/ are higher in frequency and longer in duration

To and from /ng/ are the highest and most variable in frequency and the longest in duration

10

Plosive Identification

The acoustic cues are overlaid in the acoustic cues for neighboring vowels and consonants

The listener perceives a stop and the sounds adjacent to it on the basis of their acoustic relationship to one another

Two obvious differences between stops and all other classes of sounds (except affricates)
1. complete occlusion of the vocal tract
2. stopped air is released as a transient burst of noise

11

Fricative Identification

The most important acoustic feature of fricatives is the presence of the noise generated by the turbulent airstream as it passes through the articulatory constriction

/s, z, sh, zh/ have high-frequency spectral peaks
/th, f, v/ ha relatively flat spectra

This spectral distinction divides the fricatives into 2 general categories of place
Posterior – sibilant (high intensity levels)
Anterior – non-sibilant (low intensity levels)




12

Affricate Identification

They contain acoustic cues that are present in both stops and fricatives:
The silence
Release burst
Rapid rise time
Frication
Formant transitions in adjacent sounds

13

Perception of Manner

To identify manner of articulation, listeners determine whether the sound is:
Harmonically structured with no noise (vowels, semivowels, nasals) – these are low in frequency
Contains an aperiodic component (stops, fricative, affricates) – high in frequency

14

Cues for Place

Depend on the parameter of sound frequency

Vowels and semivowels – formant relationships indicate tongue placement, mouth opening, and vocal tract length

Stops, fricatives, and affricates – the F2 transitions to and from neighboring vowels and frequency of noise components

15

Cues for Voicing

Depend more on durations and timing of events than on frequency and intensity differences

Timing differences are very important in signaling the voiced/voiceless contrast in sounds

Longer voice onset times, extended periods of aspiration and longer closer durations cue /p, t, k/

Short voice onset times, little or no aspiration, short closure duration cue the voiced stops /b, d, g/

Fricatives and affricates are perceived as voiceless when the frication is of relatively long duration

Affricates when the closure duration is also relatively long

16

Suprasegmental Perception

Perceived by the listener in terms of variations and contrasts in pitch, loudness, and length

The physical features of fundamental frequency, amplitude and duration, are the principal determinants of the perceptual qualities