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