Tut 8 Completly done !!! Flashcards
(29 cards)
Why is it difficult to localize sound ?
Tones with the same frequency that come from different locations activate the same hair cells and nerve fibers on cochela.
By what is sound localization determined ?
- Distance/Distal
- Azimuth (horizontal)
- Elevation (vertical)
Name the binaural cues and which determination process it helps :
- The Azimuth determination process
- ITD (Interaural time difference)
- ILD (Interaural lvl difference)
Define Interaural time difference:
- it is a phase delay
- Example: when the tone is closer to your rght ear it will be catched first by the right ear
- Works best by 1500 Hz or lower
- Goal: Determing side of object
Define Interaural Level difference:
- Phases of delay
- Head causes a acoustic shadow which decreases the intensity of sounds
- works best or only by high frequencys 1500 Hy or higher
- Goal: Determing side of object
What is the cone of confusuion ?
- Inside the cone they all have the same ILD and ITD which makes it (difficult / impossible) to localize the object by only using Binaural cues.
- which is why we need monaural cues
Name the monaural cues and which determination process it helps ?
- The elevatoin determination process
- Directional transfer Function (DTF)
Define (DTF) Directional transfer Function:
Sound is reflected differently within the folds of the pinnae (inside the ear) when coming from different angles !
- This creates different frequencies spectra for each sound coming from different locations. (it is bouncing in our ear)
Name Distance/Distal que:
-Intensity decreases with greater distance
- Inverse square law
( When the sound is close a small difference in distance produces a large difference in intensity
- Filtering is going on due to absorption in medium
Name the key component regarding the patway form cochlea to A1 auditory cortex.
- The signal get sends from the hair cells via nerve fibers to the cochlear nucleus.
- Past on to Superior olivary nucleus where signals met
-Than the inferior colliculus processes binaural cues - And then they reach the A1 cortex
(MORE IN DETAIL JUST REFER TO SONIC MG
Explain the jeffers circuit model:
- Each neuron respond best to a specific ITD
- neurons are connected via Axons
- Which means they receive signals from both ears.
- Neurons (coincidend neurons) only fire when both signals fire simultaneously
- Depending on location of the sound one signal must be transmitted longer then the other one.
What are specific tuned ITD neurons:
- Neurons which respond best to a certain ITD.
- Specific are rather found in animals
- but we do have more broadly tuned ITD neuron!
What is so specail about broadly tuned neurons in relationship with the hemispheres of our brian?
- More broadly tunes neruons fire at the opposite side of where the sound is coming from (located).
- Example: Sound from the left has more activity regardind broadly tuned neurons in the right hemisphere.
- It is also good for sound localization regrading the ratio of responding (Shows in % how much each hemisphere is active)
- in humans
What is the problem with the auditory scene?
The range of sound sources in the enviorment are summed up into a single complex wave which the brain can distinguish by using the auditory scene analysis.
What does the auditor scene analysis do and which heuristic does it use ?
- It seperates the sounds produced by different sources into different perceptions. Heuristic: 1. Onset time 2. Location sounds 3. Similarity of Timbre and pitch 4. Auditory continuity 5. Experience
Define the heuristic onset time:
- If two sounds start at different times, it is likely that they came from different sources
Define the heuristic location sounds:
When two sounds are separated in space, the cue of location helps us separate them with ITD and ILD
- In addition when a source moves, it typically follows a continuous path (passing car)
Define the heuristic Auditory continuity
- Sounds that stay constant or that change smoothly are often produced by the same source
- Seemd as continoius even if the are interrupted
- Continuitty effect:
Constant frequency = one tone
varying frequency is interrupted = seem as two diff tones
Define the heuristic Experience:
- Familiar melodies or speech can be restored from our brain even though a few sounds are missing or covered by a noise.
- which means we know if it is from one source or not
Define the heuristic Similarity of timbre and pitch:
Sounds that have the same timbre or pitch range are often produced by the same source
- if u have tow sounds with two timbers u group by pitch
- If not then u group by timbre
- Timbre creates different sound even if the same tone is played
What is the precedence effect ?
-If two sources with sound are represented to us spereratly with a short delay (20ms) we have a illusion that we only perceive the sound from the first speaker.
Deutsch’s scale illusion
Basically separates two different pattern into 2 single melodies which we perceive in both ears
- All the higher tones appear to be coming from the right and all the lower tones appear to be coming from the left (right handers)
- Left handers it is differnet: sometimes mirror image of right-hander’s (reversed), sometimes more complex.
Theory of unconscious inference in perception.
When faced with complex acoustic/sound, our perceptual system comes up with the most plausible interpretation in terms of our knowledge of environment.
What is auditiry stream segregaion ?
If we have one source of sound which switch really fast between high and low notes we perceive the high notes in one hemisphere and the low notes in the other hemisphere.
