Acoustic Phonetics (Lectures 7 + 8)

Vowels

A speech sound formed without significant constriction within the vocal tract and serves as a syllable nucleus

True or false - multiple vowels occur within a syllable

False

True or false - vowels can be sustained indefinitely

True

What is the primary articulator for vowels?

The tongue

True or false - consonants are good for oral examination

False - vowels are

What are the three dimensions used to describe vowels in English?

Tongue height, tongue advancement, and lip rounding

Diphthong

A vowel like sound with a gradual transition from one vowel to another (onglide to offglide)

Monophthong

A vowel with a single unchanging quality

F1 is directly related to...

Openness (more open vowels have a higher F1)

F2 is inversely related to....

Backness (more back vowels have a lower F2)

True or false - individuals with reduced speech intelligibility have a smaller vowel quadrilateral

True

What are vowels measured in the /hVd/ frame often referred to as?

Null context vowels

True or false - same formant frequencies from different speakers can be perceived as different vowels

True

Spectrum Analyzer

A device that used Fourier Analyses to determine the spectrum of stored waveform

Glides/Semivowels/Approximates

Speech sounds that have acoustic/articulatory targets identical to vowels but serve as consonants phonologically

What is a unique features of the spectrogram of a nasal consonant?

A low F1 called the nasal murmur at or below 250 Hz

Voice Onset Time

Time between the start of release burst and onset of voicing

Velar Pinch

When the F2 and F3 of velar sounds come together (F2 always falling after consonant)

Formant Transitions of Bilabials

Slightly lower F2 and F3 (F2 is rising after a consonant)

Formant Transitions of Alveolars

Slightly higher F2 and F3 (F2 depends on vowel but target is approximately 1800 Hz)

True or false - vowels preceding voiced consonants are shorter

False

What are three ways speech can have different acoustic properties at one time?

Speaker variability, context variability, rate variability

What are two problems for theories of speech perception?

Variability (speaker, context, and rate variability) and lack segmentability (speech signal cannot be divided)

What is a forced choice task?

Subjects asked to identify a stimulus using a restricted set of responses

What is an open-response task?

Subject allowed to assign any label

What is a discrimination task?

Subject is asked if two stimuli are the same or different

Psychophysics is the

study of psychological reaction to variation to variations in physical stimuli

labeling vs discrimination

Only three possible categories in /bA/-/dA/-/gA/ experiment.• If perception is categorical, adjacent stimuli within same phonetic category should sound similar.• Adjacent stimuli on either side of the boundary should sound different. • Acoustic distance between pairs always the same.• Listeners identified adjacent stimuli as "same" when in same category and "different" when in different categories.• Actual difference was always the same.

Categorical perception of VOT

• Perfect discrimination of VOT at boundary between /bA/ & /pA/.• Near-chance discrimination within a single voicing category.

True or false - phonetic identification of noise burst depends on vowel context

True

What is the motor theory of speech perception?

Listeners cannot hear small differences within a phonetic category because speakers do not produce small differences within phonetic categories (i.e., no articulation between bilabial and alveolar sounds).

True or false - there are several different acoustic cues that can contribute to identification of a given phoneme but none are necessarily critical

True - this is part of the motor theory (too many competing cues for a purely acoustic theory of speech perception)

What are arguments against the motor theory of speech production?

Individuals who cannot speak are able to perceive speech normally, categorial perception is demonstrated in infants as young as one month, production is not invariant, categorical perception in chinchillas and primates, categorical perception of nonspeech signals, and duplex perception of nonspeech signals.

Duplex Perception

Evidence for the existence of distinct systems for auditory perception and speech perception. One ear receives F1 and 2 with formant transitions and the other ear receives F3 with no transitions. The complete syllable is perceived as well as the nonspeech chirp.