Mid-Term Flashcards
What is sound?
The passage of a disturbance through a medium
What is vibration?
Displacement of air molecules caused by air pressure
Three components necessary for sound production?
1) energy source (human body)
2) vibratory source (vocal folds)
3) transmitting medium (air)
What are longitudinal waves?
- Particles are displaced in a parallel direction
- to provide energy transport to air molecules
- that consist of “compressions” and “rarefactions”
- that travel up & down to the sound energy.
What is propagation?
Transportation of energy.
What is elasticity?
Tendency to return to the original state
What is inertia?
A body in motion will remain in motion - molecules overshoot the origin
What is resistance?
Dissipation of energy, oftentimes in the form of heat
What is damping?
Resistance to vibration energy
What is characteristics of SHM (simple harmonic motion)?
periodic, repeating vibration
What is amplitude?
- Displacement/Intensity
2. how much the molecules have been displaced from neutral
What does a sinuoid wave describe?
The relationship between displacement & time
A sine wave has what two terms to describe it?
Amplitude (aka displacement or wavelength) & time
What is a period?
Time it takes to complete one cycle.
What is frequency?
The number of complete cycles that occur in 1 second (how fast it vibrates)
What is amplitude?
displacement of particles (how much its vibrating-distance/height)
What is Phase?
The point in the cycle that the vibrator is located at a given instant in time (its placement)
The number of cycles per second is measured in ___?
Hertz (Hz)
Inversely proportional to period (T) is the time it takes to complete one cycle? So, if f = 1000 Hz, what is T?
.001 sec
If T=.25ms, and F= 1000/T, what is the frequency?
onvert ms to s first
.25/1000 = .00025; 1/.00025 = [4000 Hz]
What is the frequency?
T=0.04s
F = 1/T = 1/.004 = [250Hz]
What is the frequency?
T = 100 ms
F = 1/T, so convert if it's in ms 100/1000 = .1; 1/.1 = [10Hz]
What is the period in seconds?
f = 100Hz
T = 1/f 1/100 = [.01s]
What is the period in seconds?
f = 8000Hz
T = 1/f 1/8000 = [.000125 sec]
What is the period in milliseconds?
f = 2000Hz
T = 1/f so 1/2000 = .0005 sec; .0005 x 1000 = [0.5 ms]
What is the period in milliseconds?
f = 150Hz
1/f = 1/150 = .0067 sec.; .0067 x 1000 = [6.7 msecs]
High vs. Low Frequency
Long, slow waves are ______ frequency.
Low
High vs. Low Frequency
The longer the period, the ____ cycles per second and the lower the frequency.
fewer
High vs. Low Frequency
The shorter the period, the more cycles per second the _____ the frequency.
higher
Which unit of time has a higher frequency - T = 3.3 ms or T = 0.25 ms
T = 0.25 ms
Which Hz indicates a higher frequency - 1000Hz or 50Hz
1000Hz
What is Amplitude?
Amt. of vibratory displacement, changes constantly causing inconsistent measurements.
What are four ways of measuring amplitude?
1) Instantaneous
2) Peak Amplitude
3) Peak-to-Peak
4) RMSquare
Instantaneous
amplitude at a specific point in time
Peak amplitude
displacement in one direction (positive or negative)
Peak-to-Peak amplitude
amplitude from the maximum positive peak to the maximum negative peak
Root mean square amplitude
the square root of the average of all amplitude squared - or 0.707 times the peak amplitude
Root Mean Square (RMS) Amplitude - How does it help the ear hear?
by averaging the amplitude of the entire signal and interpreting its overall loudness - similar to how we calculate RMS
Amplitude Measurement is:
pressure (y) and time (x)
When we talk about amplitude, we usually refer to the ____. It is also called _____, as it measured in _____
- RMS value
- intensity
- Dbs
Phase of sinusoid corresponds to the point in the _____ of an air molecule at a specific moment in time.
cycle
Phase is defined in
angles
Phys. Description (acoustics - sound vibration in air) vs. Human Perception (psychoacoustics) - What is frequency?
Physical descriptor that has pitch as a perceptual correlate
Phys. Description (acoustics - sound vibration in air) vs. Human Perception (psychoacoustics)
What is Amplitude?
A physical dimension that has loudness as a perceptual correlate
Phys. Description (acoustics - sound vibration in air) vs. Human Perception (PSYCHOACOUSTICS)
What is Phase?
a physical measure that helps in sound localization in terms of perception
