ILD & ITD
These are not effective for judgements on elevation since in many locations they may be zero.
JUDGING ELEVATION & DIRECTION
Hoffman had people come into the lab and try to judge where sound was coming from. They are pretty good judges before anything happens to them. Then they change the shape of the pina so they no longer have spectral cues. So they can still tell left to right but they have no idea what height the sound is coming from. However, after having this thing in your ear for 19 days you find that people start to acclimate and they can now tell where sound is coming from. So what if you take it out? People would basically just go right back to where they were. So basically the shape of your ear helps you determine where sound is coming from (up or down).
Owls have feathers that grow in the same direction on both sides of their head. This makes it so they can hunt in complete darkness. They are a really good model if you want to study hearing ability.
The superior olivary nucleus (not sure what this word actually is) has these same type of coincidence detector neurons. The idea is that if you have sound coming from both ears if they hit the olivary at the same time then they know something is coming from straight above, below, in front, or behind the person.
So you have coincidence detectors that only fire if they have two inputs at the same time. If a detector takes longer to get stimulated then the side that took longer to reach the detector is the direction the sound is coming from. Also there are different rows of coincidence detectors for different frequencies of sound. So how do you figure out which frequency is which? For example, if two people are singing the same not but on different sides of you (same frequency) how can you tell which is which? Basically you can tell the difference between the timbres but we do not know how our brain is able to do this.
AUDITORY GROUPING
We can group things based on what frequencies are coming from a similar location. Single sound sources tend to come from one location. A single sound source tends to move continuously which is called smooth motion (e.g., doplar effect). Similarity is the idea that similar frequencies tend to produce sounds of the same timbre. So the things that are closer together get grouped together. Stream segregation is something that, when sped up, you hear sounds start to segregate into multiple melodies. So if a low and high not alternate slowly they seem to jump back and forth between each other but if it is sped up then the high and low notes seem to be two separate melodies. This is similar to the idea behind gestalt principles. If the frequencies are close together it is harder to segregate notes.
EXAMPLES OF SOUND EFFECTS
There are cumulative effects of repetition on streaming, meaning that if something is played together for a short amount of time it won't segregate but if you play it for longer periods of time it can start to segregate over time. Melodies can pop out. We also segregate high notes from low notes. Grouping in timbre seems to overcome grouping high and low notes in the crossing trajectory example. There is also a "common fate"thing going on when common frequencies change. Adding vibrato to a chord causes it to sound like a voice. There is a type of auditory occlusion if a sound is played between a sound where if it was silence instead of a sound is seems that the sound cuts off instead. A similar effect to this is the picket fence effect with speech.
These are not effective for judgements on elevation since in many locations they may be zero.
JUDGING ELEVATION & DIRECTION
Hoffman had people come into the lab and try to judge where sound was coming from. They are pretty good judges before anything happens to them. Then they change the shape of the pina so they no longer have spectral cues. So they can still tell left to right but they have no idea what height the sound is coming from. However, after having this thing in your ear for 19 days you find that people start to acclimate and they can now tell where sound is coming from. So what if you take it out? People would basically just go right back to where they were. So basically the shape of your ear helps you determine where sound is coming from (up or down).
Owls have feathers that grow in the same direction on both sides of their head. This makes it so they can hunt in complete darkness. They are a really good model if you want to study hearing ability.
The superior olivary nucleus (not sure what this word actually is) has these same type of coincidence detector neurons. The idea is that if you have sound coming from both ears if they hit the olivary at the same time then they know something is coming from straight above, below, in front, or behind the person.
So you have coincidence detectors that only fire if they have two inputs at the same time. If a detector takes longer to get stimulated then the side that took longer to reach the detector is the direction the sound is coming from. Also there are different rows of coincidence detectors for different frequencies of sound. So how do you figure out which frequency is which? For example, if two people are singing the same not but on different sides of you (same frequency) how can you tell which is which? Basically you can tell the difference between the timbres but we do not know how our brain is able to do this.
AUDITORY GROUPING
We can group things based on what frequencies are coming from a similar location. Single sound sources tend to come from one location. A single sound source tends to move continuously which is called smooth motion (e.g., doplar effect). Similarity is the idea that similar frequencies tend to produce sounds of the same timbre. So the things that are closer together get grouped together. Stream segregation is something that, when sped up, you hear sounds start to segregate into multiple melodies. So if a low and high not alternate slowly they seem to jump back and forth between each other but if it is sped up then the high and low notes seem to be two separate melodies. This is similar to the idea behind gestalt principles. If the frequencies are close together it is harder to segregate notes.
EXAMPLES OF SOUND EFFECTS
There are cumulative effects of repetition on streaming, meaning that if something is played together for a short amount of time it won't segregate but if you play it for longer periods of time it can start to segregate over time. Melodies can pop out. We also segregate high notes from low notes. Grouping in timbre seems to overcome grouping high and low notes in the crossing trajectory example. There is also a "common fate"thing going on when common frequencies change. Adding vibrato to a chord causes it to sound like a voice. There is a type of auditory occlusion if a sound is played between a sound where if it was silence instead of a sound is seems that the sound cuts off instead. A similar effect to this is the picket fence effect with speech.
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