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Unformatted text preview: PSY402 Sensation and Perception November 8, 2011 Sound and the Auditory System What is sound ? • Physical definition : Pressure change in air or other medium • Perceptual definition : The experience we have when we hear o If a tree falls in a forest and there’s no one to hear it, does it make a sound? Sound as physical stimulus • Traveling wave (1) of air pressure changes (2) • • Making sound waves: o Complex sounds : Movement/vibration of objects E.g. diaphragm in loud speakers Condensation/compression and rarefication cycle o Pure tones : Movement of tuning fork Creates sine wave As wave moves, it compresses air around it Waves of pressure changes in air molecules are sound waves • Sound characteristics o Sound amplitude Amplitude : (Physical) Diference in pressure between high and low peaks of a wave Decibel (dB) used as a measure of loudness (perceptual) • dB = 20log(p/p ) • p = 20micropascals • Decibel scale relates amplitude of stimulus with psychological experience of loudness •...
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- Fall '11
- Fundamental frequency, pure tones, complex periodic sounds