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Sound and Hearing. Decibels. dB = 20log(P1/Po) P = amplitude of the sound wave Po = reference pressure = 0.0002 dynes/cm2 Decibels compress the large range of possible pressures into more manageable units - PowerPoint PPT Presentation
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Sound and Hearing
dB = 20log(P1/Po)
P = amplitude of the sound wave
Po = reference pressure = 0.0002 dynes/cm2
Decibels compress the large range of possible pressures into more manageable units
Converts a range of 0.0002 (threshold pressure) to 2,000 (jet at take off) to a range ofr 0 to 140 dB
Decibels
_____________________________________________________Sound SPL (dB)_____________________________________________________Barely audible sound (threshold) 0Leaves rustling 20Quiet residential community 40Average speaking voice 60Loud music from radio/heavy traffic 80Subway 100The Rolling Stones 120Jet engine at takeoff 140_____________________________________________________
0
90
180
270
360
Sine Wave
90° out of phase
180° out of phase
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
Middle Ear
Inner Ear
Organ of Corti
When sound causes the basilar membrane to deflect upward, thereticular membrane moves up and inward causing the stereocilla to bend outward
Auditory Pathways
a. Primary and secondary auditory cortexb. Tonontopic organization - numbers are characteristic frequencies