frequency coding and auditory space perception. three primary dimensions of sensations associated...
TRANSCRIPT
Frequency CodingAnd
Auditory Space Perception
Three primary dimensions of sensations associated with sounds with periodic waveforms
Pitch, loudness and timbre.
Pitch - sensation of "altitude" or "height" of a tone.
Loudness - sensation of "intensity" of a tone.
Timbre - quality of a sound.
Psychological Dimension Associated Physical Dimension
Pitch FrequencyLoudness AmplitudeTimbre Spectrum
Historically, there have been two major approaches to frequency coding.
Frequency theory (or timing) and Place theory
- both focused on the basilar membrane
Frequency Mechanisms
20 Hz
Place Mechanisms
150 Hz 20,000 Hz
4, 000 Hz
400 800 1,200 1,600 2,000 2,400
400 Hz tone plus harmonics
400 800 1,200 1,600 2,000 2,400
Harmonics only
800 1,600 2,400
800 Hz tone plus harmonics
400 800 1,200 1,600 2,000 2,400
Harmonics only
0
120
100
80
60
40
20
SP
L (d
B)
20 100 500 1000 5000 10,000
Audibilty Curve (Threshold of hearing)
Frequency (Hz)
Auditory Localization
A
B
Interaural delays for three different sound directions
Sound waves coming from the right side reach the rightear first, and there will be a large interaural delay beforethe sound propagates to the left ear.
With high frequency sound the head will cast a sound shadow
Slight asymmetries in arrival times between the two ears can be used to locate the lateral position of a stimulus. Delay lines and coincidencedetectors may perform this computation.