chapter 11 pt 1 Flashcards
physical definition of sound
pressure changes in the air or other medium
perceptual definition
the experience we have when we hear
how do loud speakers produce sound
by cycling through the processes of condensation and rarefication to increase and decrease hair pressure in a pattern
the pattern of air pressure changes is called a sound wave
remember: air pressure changes but the air molecules dont change place, they just move back and forth
condensation
first part of a loud speaker making sound - the diaphragm of the speaker moves out, pushing air molecules together - increase in density = local increase in air pressure above atmospheric pressure
rarefaction
second part of a loud speaker making sound
- the diaphragm moves in, pulling the air apart - air molecules spread out to fill in the increased space - decreased density = decrease in air pressure
amplitude
difference in pressure between high and low peaks of a wave
perception of amplitude
loudness
pure tone
a simple sound that occurs when changes in air pressure occur in a since wave pattern
fundamental building blocks of sound - but rare in the environment
what is the measure of loudness
decibel dB - the decibel scale relates the amplitude of the stimulus with the psychological experience of loudness
frequency
number of cycles within a given time period
oscilliations/second
how is frequency measured
in Hertz (Hz) - 1 Hz is one cycle per second
is perception of pitch related to frequency or loudness
frequency
tone height
the increase in pitch that happens when frequency is increased
fundamental frequency
the repetition rate and is called the first harmonic
periodic complex tones
consist of several pure tones called harmonics
additional harmonics
multiples of the fundamental frequency
additive synthesis
process of adding harmonics to create complex sounds
frequency spectrum
display of harmonics of a complex sound
missing fundamental
can still hear a tone without the fundamental frequency
because even when wave form changes, periodicity remains the same
what is the perceptual quality most closely related to the level or amplitude of an auditory stimulus
loudness
human hearing range
20 to 20 000 Hz