Localization Final Flashcards
What is Monotic?
Stimuli is presented to one ear
What is Diotic?
Stimuli of identical parameters is presented to both ears
What is dichotic?
Stimuli of different parameters is presented to both ears
What is localization?
The ability to identify the positionof a sound source in the environment
What is Lateralization?
The ability to identify the position of the origin that is perceived to be within the head
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
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
Who was the first person to suggest that phase differences are the root of localization?
Holmholtz
Who first suggested that time was a critical factor in localization?
Mallock
Who performed studies of localization on the roof of the Harvard Biological Laboratories?
Stevens & Newman
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
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
What is the head shadow effect?
the presence of the head alters the intensity of the sound
What is Interaural Intensity Difference (IID)
caused by dichotic presentation of stimuli
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
What frequencies are Interaural Time Difference used for localizing?
Low frequencies
What frequencies are Interaural Intensity Difference used for localizing?
high frequencies
What is the Duplex Theory?
the localization of a sound is based upon combo of interaural time and intensity difference
At what degrees does front-rear confusion occur?
0 or 180 degrees
At what frequencies was Minimum Audible Angle (MAA) best?
below 1500 Hz and above 2000 Hz
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
