Auditory Perception Flashcards
Vision perception is good at ____ information while auditory perception is good at ___ information
Vision –> spatial
Auditory –> temporal (time of event)
What kinds of information can be taken from sound?
spatial location (direction, distance) , semantic, emotion (music), substance
What is the Physical Stimulus for Sound?
the compression and spreading apart of air molecules (or water, etc)
1) This compression and rarefaction (spreading) is caused by any movement or vibrational event in a medium, such as air or water.
2) The disturbance in the medium spreads as a wave outward from the disturbance.
Concentric waves
as sound moves further away from the source, the amplitude becomes lower
Speed of sound in air
330 m/sec (quite fast)
Fourier transformation
decomposing a complex waveform into the summation of its sine wave components
- how scientists describe sound
- unique to each signal; can only be described one way
Sounds are __ dimensional signals
1 dimensional
Fundamental frequency
- the lowest frequency in a sound
- higher frequencies (harmonics) are always integer multiples of this
e. g.
- fundamental frequency is 5 hertz
- harmonics can be 10 hertz, 15, hertz, 20 hertz, etc
Harmonics
all frequencies higher than the fundamental frequency in a sound fourier transformation
*always a multiple integer of the fundamental frequency
Are sine waves commonly heard in the world?
NO, not many vibrations in the world are so pure
* most sounds are a combination of sine waves, thus the fourier transformation
Outer ear structures
pinna and ear canal
Middle ear structures
three ossicles
!! ADD IN LATER !!
Task of the middle ear
amplify sounds
!! ADD IN LATER !!
Inner ear structures
Three canals:
- cochlea
Nerves leaving the cochlea form the auditory nerve, and then the vestibular nerve
Transduction
translation of the mechanical energy (vibration) received by the cochlea structures into a neural signal
Auditory nerve
sends out auditory information in the form of neural signals to the midbrain and the cortex for higher level processing
Where does transduction occur in the ear?
Cochlea
What two cells work in the basilar membrane and tectorial membrane
- inner hair cells
- outer hair cells
Inner hair cells are ____ fibers
Afferent: SEND OUT neural information
Outer hair cells are ____ fibers
Efferent: RECEIVE neural information
Place code
Encoding of information by using the location of activity
- -> tuning of different parts of cochlea to different frequencies, in which information about the particular frequency of incoming sound wave is coded by place along cochlear partition with greatest mechanical displacement
- think: topographic mapping
where the cochlea sends info from already tells the brain information about sound
Psychological dimensions of hearing
- loudness
- pitch
- timbre
Loudness
related to the physical variable of sound pressure/amplitude
Pitch
related to sound frequency
Timbre
quality of sound; everything except pitch and loudness
1 Hz =
1 cycle/sec of vibration
What unit is used to describe pitch
Hertz (Hz)
What unit is used to describe loudness
Decibel (dB)
What is the high risk/uncomfortable threshold for hearing?
about 110 dB
What is the painful threshold for hearing?
about 130 dB
Human sensitivity to loudness ranges from…
-10 dB to 150 dB
What characteristic of sound decreases with age?
high frequencies
