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Flashcards in Instrumentation Deck (11)
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1

Neurophysiologic Development

Infant auditory sensitivity seems to be especially tuned to sounds distinctive in human speech

During babbling, the infant demonstrates sensitivity to intonation patterns of other speakers by mimicking them

Whitaker theorizes that the connections between Wernicke’s area and Broca’s area are activated when babbling temporarily ceases.

When first words arrive at 1 year of age, the child has been sensitized to the particular language and dialect of a community

2

Critical Period for Language Development

Important in the neurophysiology of speech perception

Applies to both perception and production

Most researchers agree that the critical period extends to puberty

Easier to learn a language before puberty

Cerebral lateralization is thought to be complete by puberty

3

Language Lateralization

It is believed that dominance for speech in the left hemisphere is set at an early age – 4 yrs of age
Puberty is set as an outer limit

The younger the child, the more malleable the neural correlates of language learning

The neural flexibility during the youthful critical period allows children to compensate by establishing a linguistic center in an undamaged are of the brain

Adults have little flexibility to do this

4

Motor Theory of Speech Perception

This theory posts a link between speech perception and speech production

The listener must extract information about articulation from the acoustic signal

5

Auditory Theory of Speech Perception

Uses the hearing mechanism and perceptual processing used for any other type of sound

The listener identifies acoustic patterns or features and matches them directly to the learned and stored acoustic-phonetic features of the language

6

Computer as a Research Tool

Has become pervasive in speech research

Used for
Acoustic analysis

Transform any analog signal and put into graphic displays and measure

Air pressure

Articulator movement

Brain waves

Muscle contraction

They are used to:
Average data
Measure reaction times
Record frequencies of occurrence of observed events
Provide a permanent store of data and results

7

Acoustic Analysis of Speech Production

The essence of acoustic analysis of speech is the conversion of sound waves to visual representations that be inspected, measured in various ways, and related to the articulatory gestures that produced them

8

Waveform Analysis

Useful for making acoustic measurements and displaying and measuring the output physiologic devices (e.g.: variations in air pressure, movements of the articulators, brain waves, etc.)

Waveform analysis is an interference pattern
The sum of many frequencies with different amplitudes and phase relations
Difficult to specify component frequencies from a waveform alone – spectral analysis is used for this

9

Spectral Analysis

Spectrogram can depict the rapid variations in the acoustic signal that characterize speech

Spectrogram provides an analysis of the frequency components of the acoustic signal in terms of its harmonics or its peaks of resonance (formants).

10

Narrowband Spectrogram

used for representing the harmonics of the glottal source

Darker bands represent the harmonics closest to peaks of resonance in the vocal tract
Lighter bands represent harmonics whose frequencies are further from the resonance peaks

Good for assessing intonation

Each spectral snapshots are of sections about 20 ms

11

Wideband Spectrogram

used more when studying phonetics

See changes in the resonances of the vocal tract – formant frequencies

Each spectral snapshot are of sections about 3 ms in length