SLHS 312 Exam 3

What is the power source in speech production

respiratory tract (pulmonary system)

what is responsible for sound creation in speech production

larynx and vocal tract

what is responsible for sound modulation in speech production

resonance and articulation (vocal tract —> pharyngeal cavity, oral cavity, nasal cavity)

What is a model?

a purposeful representation of reality

a simplification of a system or any of its parts

models can be used to test theories using experimental approaches

models are constructed so that they can be manipulated in a controlled manner

What is a theory

a conceptualized framework that attempts to explain a phenomenon

researchers set out to test theories, as a result theories are always changing

theory dictates practice

Models can be used to test ____

theories

What is von Bekesy’s model of the traveling wave

Von bekesy developed a mechanical model of the basilar membrane using a sheet of rubber varying thickening in a tank of water (endolymph of the cochlea)

• Wave of different frequencies were introduced into the tank

  • High frequencies, the thinner part of the sheet vibrated at the highest amplitude

  • Low frequencies, the thicker part of the sheet vibrated at the greatest amplitude

Effects of hydration on voicing/phonation

phonation threshold increases with dehydration and then decreases to normal levels with rehydration

what do target models describe

speech production as a physical specification of a planned phonological unit

targets are hypothesized to be ___ (articulatory) or ____ (auditory)

spatial, acoustic

describe a spatial model

internalized motor map of the vocal tract in the brain that allows the speaker to move articulators to specific regions within the vocal tract

describe the goal of an acoustic auditory model

the goal to be achieved is the acoustic output

describe the feedback of the DIVA model

from motor and sensory signals transform error inputs into feedback based motor commands

describe the feedforward of the DIVA model

control system is tuned during attempts to imitate a learned speech sound target

what is acoustic invariance theory

for each distinct phoneem, there is a set of acoustic features

our perception of phonemes is provided by these constant/invariant acoustic cues

therefore, the listener must compare acoustic features heard against a stored template

what is the problem with acoustic invariance theory

speech sounds are not invariant. They change depending on the sounds surrounding them, for example, formant differences in vowels for different talkers, effects of co articulation and speech rate

what is direct realist theory (carol fowler)

speech perception does not rely on specialized processes but is similar to other types of perception (e.g., vision)

we perceive objects directly rather than by reconstructing and interpreting the object from sensory input to the brain

what is the problem with direct realist theory

vastly underestimates complexity of perception

also assumes invariant features in speech and there is a lack of evidence for invariant qualities in speech elements

TRACE Model

suggests there are interactive connections among units in a network at 3 levels (features, phonemes, and words)

poses that units within a level are competing for activation by acoustic stimuli

activation of a set of features gives activation to a set of phonemes, which in turn activates some possible words. The more one word is activated, the more other possible words are inhibited

Motor theory of speech production

hypothesis that people perceive spoken words by identifying the vocal tract gestures with which they are pronounced rather than by identifying the sound patterns that speech generates

link between speech production and speech production

delayed auditory feedback (DAF)

In fluent speakers, DAF affects motor behavior by disrupting the forward flow of speech

contradiction to basic tenet of motor theory

pre-lingual infants up to 10 months of age can discriminate sounds in their language and most of the world’s languages

revised motor theory

listener does not, however percieve the actual movement of the articulators but an abstract articulatory plan (called a gesture)

mirror neuron

a neuron that fires both when an individual performs and motor act and when the individual observes the same motor action being performed by another person

Speech perception is based on

ability to discriminate and identify the acoustic phonetic features of acoustic signal

what is meant by “speech is dynamic”

listeners use dyanmic cues with contextual clues and linguistic knowledge to decode speech

what is the role of redundancy in speech perception

speech perception can be successful with filtered and distorted speech reveals that acoustic cues can be ambiguous or absent

Most perception occurs in ____

Context

Ex. /nd/ expected at end, not beginning of word

What is most helpful for identifying vowels

dynamic spectrotemporal patterns (changing formant patterns)

Ex. cake vs kick show different relative formant shifts

How are most consonants perceieved

Categorically

attenutation