Tut 8 Completly done !!!

Question 1

Why is it difficult to localize sound ?

Answer 1

Tones with the same frequency that come from different locations activate the same hair cells and nerve fibers on cochela.

Question 2

By what is sound localization determined ?

Answer 2

1. Distance/Distal
2. Azimuth (horizontal)
3. Elevation (vertical)

Question 3

Name the binaural cues and which determination process it helps :

Answer 3

• The Azimuth determination process
• ITD (Interaural time difference)
• ILD (Interaural lvl difference)

Question 4

Define Interaural time difference:

Answer 4

• 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

Question 5

Define Interaural Level difference:

Answer 5

• 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

Question 6

What is the cone of confusuion ?

Answer 6

• 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

Question 7

Name the monaural cues and which determination process it helps ?

Answer 7

• The elevatoin determination process

- Directional transfer Function (DTF)

Question 8

Define (DTF) Directional transfer Function:

Answer 8

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)

Question 9

Name Distance/Distal que:

Answer 9

-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

Question 10

Name the key component regarding the patway form cochlea to A1 auditory cortex.

Answer 10

• 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

Question 11

Explain the jeffers circuit model:

Answer 11

• 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.

Question 12

What are specific tuned ITD neurons:

Answer 12

• Neurons which respond best to a certain ITD.
• Specific are rather found in animals
• but we do have more broadly tuned ITD neuron!

Question 13

What is so specail about broadly tuned neurons in relationship with the hemispheres of our brian?

Answer 13

• 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

Question 14

What is the problem with the auditory scene?

Answer 14

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.

Question 15

What does the auditor scene analysis do and which heuristic does it use ?

Answer 15

- 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

Question 16

Define the heuristic onset time:

Answer 16

• If two sounds start at different times, it is likely that they came from different sources

Question 17

Define the heuristic location sounds:

Answer 17

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)

Question 18

Define the heuristic Auditory continuity

Answer 18

• 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

Question 19

Define the heuristic Experience:

Answer 19

• 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

Question 20

Define the heuristic Similarity of timbre and pitch:

Answer 20

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

Question 21

What is the precedence effect ?

Answer 21

-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.

Question 22

Deutsch’s scale illusion

Answer 22

Basically separates two different pattern into 2 single melodies which we perceive in both ears

1. 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)
2. Left handers it is differnet: sometimes mirror image of right-hander’s (reversed), sometimes more complex.

Question 23

Theory of unconscious inference in perception.

Answer 23

When faced with complex acoustic/sound, our perceptual system comes up with the most plausible interpretation in terms of our knowledge of environment.

Question 24

What is auditiry stream segregaion ?

Answer 24

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.

Question 25

Define harmonicity:

Answer 25

• Auditory system fuses components together that stand in harmnoic relationship

Question 26

Explain the continuity illusion:

Answer 26

• Sound is perceived as being continued while interrupted
• works only if the noise which interrupts the tone has high intensity
• Noise need to include at least similar frequencies

Question 27

Define timbre:

Answer 27

• Different amplitudes of the harmonics are called timbre
• Depens on Attack (fade in how quickly sound comes in) and Decay (fade out)
• If u change them the timber will be changes so u would interpretaed it as coming from a diff source (envelope)

Question 28

Define the hearing range ?

Answer 28

• Range from 20 to 20000Hz

Question 29

What is the pitch missing fundamental ?

Answer 29

• The fundamental frequency is missing
• To create the missing fundamental frequency we just subtract the two harmonics from each other to create the FF
• So if u play two tones with 100Hz and 150Hz it will end up sounding like a 50Hz frequency
• IN telephones