Fourier transform
a sound wave generation requires....
a source and medium
what figure shows us to directly identify harmonics of a complex wave?
a spectrum
charting fourier analysis: -what do we use?
a spectrum. it shows sine components of a complex wave
complex waves:
all speech sounds, periodic, can apply fourier analysis (break apart) /theorem (can combine sine waves to make a complex wave)
fourier analysis:
any periodic waveform, no matter how complex it is, can be closely approximated by adding together a number of sinusoidal waves
charting non-repetitive wave:
continous spectrum
fundamental frequency and higher harmonic relationship
nth H= n * F0
why do we use fourier analysis?
our auditory system preforms a similar analysis that enables us to learn different sounds
simple waves:
simple sine (periodicity, single frequency) , 1 frequency, periodic,
difference between sine and complex waves:
sine has 1 frequency, complex has additional frequencies
propagation velocity:
speed of sound (about 35,000 cm/sec)
acoustics:
the science and technology of the production, transmission, reception, and effects of sound and vibration
phase:
timing of wave propagation: in phase of out of phase
the result of fourier analysis can be see from a ___
waveform
velocity-frequency-wavelength relationship:
-c=(frequency)(wavelength) -frequency= 1/T c=velocity (cm/sec) wavelength= cm frequency=Hz
wave propagation: compression and rarefaction
-compression is high pressure -rarefaction is low pressure
wavelength:
-distance between recurring events
Period:
-duration of a cycle -(s) or (ms)
amplitude:
-maximum deviation from the zero line in air pressure (think height) -dB -correlates to loudness
frequency:
-number of times that a periodic event repeats itself for some standard interval of time -Hz -correlates to pitch perception - F= 1/T
what is the relationship between fundamental frequency and harmonics?
-sine waves that add together to make a periodic complex wave are harmonically related -those sine waves are called harmonics -the harmonic with the lowest frequency (the 1st harmonic), is the F0 of a complex wave
charting periodic/repetitive wave:
-use a line spectrum