PSYC1011 Lecture Notes - Lecture 22: Stapes, Temporal Lobe, Basilar Membrane
Hearing
Outline
• Describe the key components of sound waves and how they relate to perception
• Explain the transduction of acoustic energy
• Give examples of how auditory information is represented in the cortex
The nature of sound
• Sound
o Vibration of air molecules
o Travels at a constant speed
▪ Slower than light
o Energy dissipates with distance
o Acoustic energy
• Frequency
o Measured in number of cycles per second (Hz)
o Determines pitch
▪
o Spectrograph - frequency-time graph
▪ Measures how much energy occurs at which frequency over time
• Warm - high energy
• Blue - no energy
▪
o Sound spectrum
▪ Infrasound - <20Hz
▪ Acoustic
• Human hearing
• 20Hz - 20KHz
▪ Ultrasound > 20KHz
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▪
o Animals are sensitive to different ranges of frequency
▪
• Audio information on CDs - sampled at 44.1 kHz
• Max reproducible sound is half
• 22.05 kHz ~ max sensitive frequency
• Complexity
o Simple sound wave - oscillations at one frequency
• E.g. from tuning fork
o Complex sounds - contain energy at multiple frequencies
• Typical sounds are complex
•
▪ Fundamental - lowest frequency
▪ Harmonics - integer multiples of the fundamental
o Timbre
▪ Determined by sound complexity (harmonics)
▪ Pitch - determined by fundamental frequency (lowest f)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Outline: describe the key components of sound waves and how they relate to perception, explain the transduction of acoustic energy, give examples of how auditory information is represented in the cortex. Sound: vibration of air molecules, travels at a constant speed. Slower than light: energy dissipates with distance, acoustic energy. Frequency: measured in number of cycles per second (hz, determines pitch, spectrograph - frequency-time graph, measures how much energy occurs at which frequency over time, warm - high energy, blue - no energy, sound spectrum. Fundamental - lowest frequency: harmonics - integer multiples of the fundamental, timbre, determined by sound complexity (harmonics, pitch - determined by fundamental frequency (lowest f, amplitude. Intensity of pressure oscillations: measured in decibels (db, related to perceived loudness. Loudness: also depends on frequency, audibility curve, threshold of hearing. Sensing sound: acoustic to neural energy, transduction of sound occurs in the ear, outer ear.
