Chapter 2 Flashcards
What is sound?
- vibration
- auditory sensation
- organized movement of molecules
Frequency
Number of complete cycles that occur in one second
1 Hz= 1 vibration/second
Pitch
Phase
Start phase is at 0
Phase is always relative to the start point
Amplitude
Measure of displacement
How far an object moves, peak to peak or baseline to peak
Fourier’s theorem
Different shapes of time waveforms can be created by varying the relative amplitudes and phases of the summed sinusoids
Force
Newton’s second law
= mass x acceleration
1 newton = 1 kg*m/s^2
Work
When a force acts through a certain distance
F x d, unit is newton meter or Joule
The more force applied to an object, the more work is done
Energy
The capacity for doing work, you must have energy to accomplish work
- 1 joule is 1N acting through a distance of 1meter
Power
The rate at which work being done The time within work is done = energy/time = joule/second = watts
Energy converted to another form
Pressure
Force/unit area
= pascals
1 Pa = 1N/m2
Larger pressure means a larger force being applied
Measure of sound amplitude
Speed of sound
c= 345 m/s
Dependent on temp, density and humidity
Goes up when temp and humidity go up and when density goes dow
Standard pressure reference
20 microPascals
Sound pressure equation
dB = 20 log (p/p reference)
Power/intensity equation
dB IL = 10log (I/I reference)
Units in watt/m2
Intensity
Measure of sound power
Watt/m2
Relationship between intensity and pressure
Power = amplitude2 Intensity = pressure2 I = p2
Standard power/intensity reference
10^-12 w/m2
dB log scale
The closer you are to zero, the less pressure change you need to perceive the difference
Period
Wavelength, one full cycle
1/f
Friction
Does not alter frequency, only amplitude
SAM tones amplitude line spectra
Fc (carrier frequency) 500Hz
Fc + Fm (mod freq) 560Hz
Fc - Fm 440Hz
*there is no energy at Fm
Simple harmonic motion
When an object displaced from its equilibrium position is acted on by a force proportional to the displacement, the object will undergo a periodic motion (in the absence of friction)
Instantaneous phase
Start phase both equal 0, but phase at different points in time differs between two waves (different frequency)
Harmonic complex tone
All component frequencies are an integer multiple of the first one
