Localization Final Flashcards by Kayla Trosky

What is Monotic?

Stimuli is presented to one ear

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What is Diotic?

Stimuli of identical parameters is presented to both ears

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What is dichotic?

Stimuli of different parameters is presented to both ears

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What is localization?

The ability to identify the positionof a sound source in the environment

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What is Lateralization?

The ability to identify the position of the origin that is perceived to be within the head

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Who first studied localization & when? How? Hypothesize?

Venturi in late 18th century
tested normals and hearing impaired localization skills while playing a flute
intensity differences between ears caused localization

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Problems with Intensity Theory?

front-back confusion- we have difficulty determining if sound is coming from front or back, this theory is not true because it will be quieter from behind
side placement of stimulus- either front or back of binaural axis, we have difficulty determining if its coming from font or back of binaural axis

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Who was the first person to suggest that phase differences are the root of localization?

Holmholtz

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Who first suggested that time was a critical factor in localization?

Mallock

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Who performed studies of localization on the roof of the Harvard Biological Laboratories?

Stevens & Newman

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What were the results of Stevens & Newman’s study?

localization of sound is most accurate below 1000 Hz and above 4000 Hz
greatest errors found between 2000 and 4000 Hz

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Why do the most errors in localization occur between 1500 Hz and 2000 Hz?

the external auditory canal and pinna naturally amplify sound at these frequencies, this change in amplification could throw off our ability to localize

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What is the head shadow effect?

the presence of the head alters the intensity of the sound

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What is Interaural Intensity Difference (IID)

caused by dichotic presentation of stimuli

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Results of research done on Interaural Intensity Difference?

results found no differences in IID between ears when sounds were presented at 0 and 180 degrees
IIDs occurred when stimulus was closer to one ear than other
Low frequencies are affected less because they have longer wavelengths than high frequencies, head shadow will affect high frequencies more
max differences were at 90 degrees

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What frequencies are Interaural Time Difference used for localizing?

Low frequencies

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What frequencies are Interaural Intensity Difference used for localizing?

high frequencies

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What is the Duplex Theory?

the localization of a sound is based upon combo of interaural time and intensity difference

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At what degrees does front-rear confusion occur?

0 or 180 degrees

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At what frequencies was Minimum Audible Angle (MAA) best?

below 1500 Hz and above 2000 Hz

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What is concurrent minimum audible angle (CMAA)?

simultaneous presentation of stimulus

Similarities between CMAA and MAA?

most accurate when presented in front of subject
least sensitive when off to the side
affected by spectral differences

What is Minimum Audible Movement Angle (MAMA)?

signal being present while in movement

What is the Precedence Effect?

within a certain time frame, the earlier sound will dominate the later arriving signal, or the sound that is louder will dominate the softer signal

What is the Phantom Effect?

Occurs when sound is presented through 2 speakers and the origin is perceived between them

Perceptual Groups

- fundamental freq - onset differences - differences with prior sounds - changes in amplitude or freq - location

What is Timbre

the attribute of auditory sensation in terms of which a listener can judge that 2 sounds similarly presented and having the same loudness and pitch are dissimilar

Time dependent components that give us timbre.

- periodicity vs. aperiodicity - constant or fluctuant - changes in characteristics over time - preceding or subsequent stimuli

Effects of onset differences

- if signal preceded masker then threshold was lower | - if signal preceded masker, but signal shut off when masker started, then the lower threshold was unaffected

What is Masking?

the process by which the audibility of one signal is affected by another and the amount by which it is affected

What is speech composed of?

complex waveforms that vary in frequency and amplitude

How are perception and production of speech related?

in order for us to understand the speech sounds we have to be able to produce them

What are phonemes?

group of sounds that are considered the components of the same language by native speakers of that language, smallest components of words

What does production of speech involve?

- lungs - trachea - larynx - oropharynx - mouth/lips

How does speech production occur?

- vocal folds move in order to change airflow - opening and closing of folds creates periodic changes in the air coming out - vocal tract is a variable resonator - characteristics of vocal tract introduce resonance into speech

What kind of fundamental frequencies will larger volume resonators have?

lower

Consonant production characteristics

- place of articulation | - manner of articulation

Places of articulation

- bilabial - labiodental - interdental - alveolar - palatal - velar - glottal

Manners of articulation

- stops - fricatives - affricates - nasals - glides - liquids

What is speech perception?

a search for meaning, based on ability to discriminate between identifying acoustic-phonetic features of the waveform

What is segmentation?

when we hear sounds, we perceive a series of separate sounds that can be combined in an innumerable number of ways, the listener combines these separate sounds into meaningful words, phrases, etc.

How are vowels characterized?

by patterns of vocal tract resonances (formants)

How are consonants characterized?

by more rapid movements of articulators

What is the perception of speech with a hearing loss dependent on?

- audibility | - suprathreshold recognition ability

Why is vowel perception not typically affected by hearing impairment?

vowels hold the most acoustic energy of the phonemes

What are the models of speech perception?

- motor theory - cue-based approach - TRACE model

What is motor theory?

our perception of speech is in part dependent upon our perception of the movements made by the articulators, etc.

What is cue-based approach? What is the process?

- we process speech based upon distinct representation of speech into segments - Process: detect envelope for significant landmarks, extract the acoustic cues, cues are combined to then perceive words

What is TRACE model?

our perception of speech is based upon 3 layers of perception of phonetic cues, called nodes

What does speech perception have to do with audiology?

- speech testing (retrocochlear pathology usually have bad speech perception) - hearing aid programming - cochlear implant programming