PSYB65H3 Chapter Notes - Chapter 10: Sound, Sound Energy, Minimax
CHAPTER 10 HOW DO WE HEAR, SPEAK, AND MAKE MUSIC
10-1 Sound Waves: Stimulus for Audition
●Sounds waves move through compressible media → air, water, ground BUT not through vacuum of outer
space
●Cycle → one complete peak and valley on the graph
○Change from one max or min air pressure level of sound wave to the next max/min level
→ Physical Properties of Soundwaves
●Sound = mechanical energy we hear
●Sound wave energy has 3 physical attributes
○Frequency
○Amplitude
○Complexity
→ Sound Wave Frequency
●Sound waves in air travel at fixed speed of 1100 ft / sec
○More than 4X faster in water
●Sound energy varies in wavelength
●Frequency → number of cycles a wave completes in given amount of time
○Measured in cycles/sec → hertz (Hz)
○One hertz = 1 cycle/sec
○Sounds we perceive as low pitched have fewer wave frequencies (fewer cycles / sec)
○Sounds we perceive as high pitched have more wave frequencies
○We can only perceive sound waves only in limited range of frequencies
○Human’ hearing range = ~20 - 20,000 Hz
●Range of sound wave frequencies heard by diff species varies extensively
●Differences in sound wave frequencies become differences in putch when heard
●Perfect pitch → being able to discriminate b/w one musical note and another
○Suggests a genetic influence
find more resources at oneclass.com
find more resources at oneclass.com
→ Sound Wave Amplitude
●Strength → causes differences in perceived intensity or loudness
●Frequency stays the same
●Increased air mol compression intensifies energy in sound wave -- >amps the sound
●Sound wave amplitude measured in decibels (dB) → strength of a sound relative to threshold of
human hearing as a standard (0 decibels)
●Human NS evolved to be sensitive to soft sounds → blown away by extremely loud sounds
→ Sound Wave Complexity
●Pure tones → sounds with single frequency
●Most sounds mix wave frequencies together in combinations → complex tones
●Using Fourier analysis we can break down complex tone into its many component pure tones
●Fundamental frequency (wave 1) → rate at which the complex waveform pattern repeats
○Waves 2-20 = overtones → higher frequency sound waves that vibrate at whole #
(integer) multiples of the fundamental frequency
●Diff musical instruments sound unique because they produce overtones of diff amplitudes
●Pure tones blend into complex tones
○Complex tones emanate from musical instruments, human voice, birdsong, machines, or
repetitive mechanisms
●Key feature of complex tones → periodicity
○Fundamental frequency repeats at regular intervals
●Noise → sounds that are aperiodic, or random
→ Perception of Sound
●Frequency of waves determines pitch of the sound heard by the brain
●Height (amplitude) of waves determines sound’s loudness
●Humans can detect displacement of air mol of about 10 picometers
●Auditory system also proficient at simultaneously perceiving diff sounds
○Capable bc each frequency of change in air pressure stimulates diff neurons in auditory system
→ Properties of Language and Music as Sounds
●Language and music both convey meaning and evoke emotion
●Brain evolved systems that analyze sounds for meaning
○Speech in left temporal lobe
○Music in right temporal lobe
●Humans have great capacity for learning and remembering linguistic and musical info
●Language facilitates communication
find more resources at oneclass.com
find more resources at oneclass.com
●Music helps us to regulate our own emotions and to affect emotion of others
○Play music to enhance social interactions and gatherings
○Unique to humans
●Delivery speed of language and music
○Sound segment = distinct unit of sound
○Normal speed for speech is on the order of 8-10 segments/sec
○Capable of understanding speech at nearly 30 segments/sec
→ Properties of Language
●Experience listening to particular language helps the brain to analyze rapid speech
●Unique characteristic of our perception of speech sounds → our tendency to hear variations of a
sound as if they were identical
○Even though sound varies considerably from one context to another
→ Properties of Music
●Subjective properties that ppl perceive in musical sounds differ from one another
●One subjective property = loudness → magnitude of sound as judged by a person
○Related to the amplitude of a sound wave measured in dB
○Loudness is also subjective
○Perception of loudness also changes with context
■Example: reduction in road noise alters your perception of music’s loudness
●Another subjective property of musical sound is pitch → position of each tone on a musical scale
as judged by listener
○Any musical note is defined by its fundamental frequency → lowest frequency of sound
wave pattern
○Right temporal lobe extracts pitch from sound (speech OR music)
○Prosody → perceived melodic tone of a voice
■Pitch contributes to this
●Final property of musical sound = quality /timbre → perceived characteristics that distinguish
particular sound from all others of similar pitch and loudness
10-2 Functional Anatomy of the Auditory System
●Ear collects sound waves from surrounding air → converts their mechanical energy to electrochemical
neural energy
○Long route through brainstem→auditory cortex
●Auditory system structured to decode frequency, amplitude, and complexity
●In humans evolution of sound-processing systems for language and music was accompanied by
enhancement of specialized cortical regions
○**temporal lobe
→ Structure of the Ear
●Consists of outer ear, middle ear, and inner ear
→ Processing Sound Waves
●Pinna → funnel-like external structure of outer ear
○Both the pinna and external ear canal made of cartilage and flesh
○Designed to catch sound waves in environment and deflect into external ear canal
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Chapter 10 how do we hear, speak, and make music. Sounds waves move through compressible media air, water, ground but not through vacuum of outer space. Cycle one complete peak and valley on the graph. Change from one max or min air pressure level of sound wave to the next max/min level. Sound wave energy has 3 physical attributes. Sound waves in air travel at fixed speed of 1100 ft / sec. Frequency number of cycles a wave completes in given amount of time. Sounds we perceive as low pitched have fewer wave frequencies (fewer cycles / sec) Sounds we perceive as high pitched have more wave frequencies. We can only perceive sound waves only in limited range of frequencies. Human" hearing range = ~20 - 20,000 hz. Range of sound wave frequencies heard by diff species varies extensively. Differences in sound wave frequencies become differences in putch when heard.
