PSYC-2200 Lecture Notes - Lecture 9: Saccade, Kanzi, Asian Elephant
16 Aug 2018
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Tuesday, March 14, 2017
Chapter 9 - Speech and Language
Auditory Cognition
-Flute = high frequency
-Bass guitar = low frequency
-frequency is the measure, can be measured in Hertz, but loudness and pitch are
perceptual qualities
-Frequency = pitch
-Amplification/Amplitude = loudness
Perception of Loudness
Magnitude Estimation
- perception does not always keep pace with actual loudness, we can often
overestimate
Frequency dependent
-play at 40 DB (Decibels) violin will be heard very clearly, but the perception of the
Cello will be reduced, more so the double Bass
-in order to hear low frequency sounds, you have to make it louder, lower decibel =
louder in order to perceive it
-can play a violin and a double bass at the same decibel level, and you will perceive
the violin as louder, but the louder you play it, the more the will “level out”, or you will
perceive them at equal loudness
-Location for sounds is not present within the sounds themselves - must be calculated
-auditory space - surrounds an observer and exists wherever there is sound
-how to separate sounds in auditory space?
-use location cues
Interaural Time Difference (ITD)
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Interaural Level Difference (ILD)
Spectral Cues
-surrounded by an auditory space
- ITD: (picture on page 7) in our brain stem, automatic process, if a sound is coming
directly at me, the sound enters each ear at roughly the same time, if it comes from
the side of me, it hits one ear first, and then the second, minimal time lag, less than a
millisecond, but there WILL be a difference, and it’ll tell us where it’s coming from
- sound that enters the one ear first will be louder than the sound the enters the
second ear as well
-ILD: picture on page 8 - acoustic shadow - only works for sounds of a high enough
frequency, low frequency sounds aren’t really blocked by your head, so it can make it
harder to tell where it’s coming from (Car bass vs Flute)
Cone of Confusion
-if the sound is coming from below, exactly same time difference as if sound is coming
from above
-SEE PIC ON PAGE 9 OF SLIDES
-Brain calculates frequency differences to figure out where sounds come from
depending on how it bounces around our ears - SEE PIC ON PAGE 10
hearing range across species
Picture on page 11
-humans have a low-end frequency range, typically 20Hrz - 20000Hrz
Using Sound
-sound is used by many animals for a host of cognitive tasks
-Communication
-Navigation
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Tuesday, March 14, 2017
-predation
-some animals emit and detect sounds beyond the range of human hearing
-Infrasonic (low frequency)
-ultrasonic (High frequency)
Size Exaggeration Hypothesis of Vocal Production
-we assume that smaller things make high frequency noises, and larger things make
lower frequency noises
-ex: violin vs. cello, trumpet vs. euphonium
Purring vs. low frequency vocal
-purring produced by throat muscle contraction - more like a shivering of the throat
muscles, not technically a voice (not different types of purrs)
-purring limited in sound complexity and quality
Elephant Communication:
-live in fission-fusion families
-Matriarchies
-group cohesion/group protection
-both high frequency and low frequency calls
Elephant Vocal Production
-nasal passage (trunk)
-oral passage (mouth)
Asian Elephant “Koshik”
-spent 7 years with only human contact
-Able to mimic a handful of Korean words
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Document Summary
Frequency is the measure, can be measured in hertz, but loudness and pitch are perceptual qualities. Perception does not always keep pace with actual loudness, we can often overestimate. Play at 40 db (decibels) violin will be heard very clearly, but the perception of the. Cello will be reduced, more so the double bass. In order to hear low frequency sounds, you have to make it louder, lower decibel = louder in order to perceive it. Location for sounds is not present within the sounds themselves - must be calculated. Auditory space - surrounds an observer and exists wherever there is sound. Sound that enters the one ear rst will be louder than the sound the enters the second ear as well. If the sound is coming from below, exactly same time difference as if sound is coming from above. See pic on page 9 of slides.
