NEUR 2600 Lecture Notes - Lecture 10: Positron, Membrane Potential, Basilar Membrane
CHAPTER 10: HOW DO WE HEAR, SPEAK, AND MAKE MUSIC
● Language and music
○ Oral language of every known culture follows similar basic structural rules, and
people in all cultures make and enjoy music
○ Language and music allow us to organize and to interact socially
○ People who can communicate their intentions to one another and to their children
presumably are better parents than those who cannot
● Sound waves: stimulus for audition
○ Sound wave
■ Undulating displacement of molecules caused by changing pressure
■ Visualizing a sound wave
● Air molecule density plotted against time at a single point relative
to the tuning fork’s right prong
● Physicists call the resulting cyclical waves, sine waves
● A cycle is one complete peak and valley on the graph
● It is the change from one maximum or minimum air pressure level
of the sound wave to the next maximum or minimum level
■ Physical properties of sound waves
●
● Frequency
○ Number of cycles that a wave completes in a given amount
of time
■ Measured in hertz, or cycles per second
○ Corresponds to our perception of pitch
■ Low pitch, low frequency (fewer cycles/second)
■ High pitch, high frequency (many cycles/second)
○ Differences in frequency are heard as differences in pitch
■ Each note in a musical scale has a different
frequency
● Hearing ranges amongst animals
○ The frequency ranges of whales, dolphins and dogs are
extensive
○ Humans’ hearing range is broad but we do not perceive
many sound frequencies that other animals can both make
and hear
○ Very low frequency sound waves travel long distances in
water
■ Whales produce them for underwater
communication over hundreds of miles
○ High-frequency sound waves echo and form the basis of
sonar
■ Dolphins produce them in bursts, listening for
echoes from objects
● Amplitude
○ The intensity, or loudness, of a sound, usually measured in
decibels (dB)
○ The magnitude of change in air molecule density
○ Corresponds to our perception of loudness
■ Soft sound, low amplitude
■ Loud sound, high amplitude
○ Sound wave amplitude
■ The human nervous system is sensitive to soft
sounds. People regularly damage their hearing
through exposure to very loud sounds or by
prolonged exposure to them. Prolonged exposure
to sounds louder than 100 decibels is likely to
damage human hearing
■ Rock bands routinely play music registers higher
than 120 decibels and sometimes as high as 135
decibels
■ Because of the high sound levels, hearing loss is
common is symphony musicians
■ Prolonged listening to loud music through
headphones or earbuds is responsible for
significant hearing loss in many young people
● Complexity
○ Pure tones
■ Sounds with a single frequency
○ Complex tones
■ Sounds with a mixture of frequencies
Document Summary
Chapter 10: how do we hear, speak, and make music. Oral language of every known culture follows similar basic structural rules, and people in all cultures make and enjoy music. Language and music allow us to organize and to interact socially. People who can communicate their intentions to one another and to their children presumably are better parents than those who cannot. Undulating displacement of molecules caused by changing pressure. Air molecule density plotted against time at a single point relative to the tuning fork"s right prong. Physicists call the resulting cyclical waves, sine waves. A cycle is one complete peak and valley on the graph. It is the change from one maximum or minimum air pressure level of the sound wave to the next maximum or minimum level. Number of cycles that a wave completes in a given amount of time. Measured in hertz, or cycles per second. Differences in frequency are heard as differences in pitch.
