Nature of Sound Flashcards
what can change speed of sound?
temp, humidity & elevation
speed of sound in meters?
340 m/s
speed of sound in feet?
1 ft/ms
speed of sound in km?
1 km/3 sec
speed of sound in miles?
1 mi/5 sec
propagation and reflection create what?
our sense of space
what is the width of the wave?
amplitude
what is the length of a wave?
frequency
what is the extent of compassion and rarefaction?
amplitude
what kind of wave - vibration is perpendicular to the propagation
transverse wave (pond)
what kind of wave - vibration is parallel to the propagation
longitudinal wave (sound)
amplitude is measured in
dB
changes in amplitude show (2)
pressure varying in the air & voltage varying in a cable or wire
dBSPL
decibels of Sound Pressure Level (air)
lowest dBSPL
threshold of hearing (0 dBSPL)
highest dBSPL
human pain threshold
dBFS
decibels of Full Scale (computer)
highest dBSPL
0
what is our perception of loudness is affected by?
duration and frequency
panning, dynamic plugins, expanders, gates, limiters, compressors are functions of
amplitude
what is dynamic range?
the dB in which is will reproduce sound properly, between the noise floor and distortion
what_s the difference between frequency and pitch?
frequency can be measured, pitch is something we perceive
only a sin wave has a single frequency, everything else has
overtones
what is EQ?
a collection of filters which manipulate the timber
range of human hearing
20Hz - 20,000Hz (18kHz actually)
oscilloscope
time (x) amp (y), the exact path the sound will make in the air coming out of the speaker
spectrum analyzer
freq (x) amp (y)
spectrogram
spectrum analyzer over time
what makes instruments sound different?
the relative levels of the partials
how does an oscilloscope show amplitude changes?
vertical changes
how does an oscilloscope show frequency changes?
more waves
how does an spectrum analyzer show amplitude changes?
vertical changes
how does an spectrum analyzer show frequency changes?
horizontal changes
how does an sonogram show amplitude changes?
color
how does an sonogram show frequency changes?
vertical changes
what does signal flow start with?
sound source
what is a microphone and what does it do?
an input transducer, converts sound pressure variations into voltage variation
what are speakers or headphones what do they do?
output transducers, convert voltage variation into sound pressure variation
what two components are part of audio interface?
a microphone preamp & an A/D converter
