SLHS 305 Exam 2 Questions and Answers Fully Solved Graded A+
Acoustics - Answers Properties of sounds as they travel in air and how they are affected by objects in
their environment
Waveform (time domain) - Answers When the pattern of movement is displayed with amplitude as a
function of time
Condensation - Answers Increased density of air molecules, corresponds with an increase in sound
pressure
Rarefaction - Answers Decreased density of air molecules, corresponds with a decrease in sound
pressure
Simple vibrations - Answers Also called "pure tones"
Characterized by their physical (acoustic) dimensions of frequency, amplitude, and starting phase.
Pure-tone (sine wave) - Answers "sinusoids"
"Regular repetitive movements"
Relative to phase angle (sin θ)
Sin θ = x/r
Cycle - Answers The pattern of movement as the object goes through its full range of motion one time
One cycle represents the movement of an object from its starting point, to maximum peak, to negative
peak, back to its starting point
Frequency (and units) - Answers How many cycles occur per second
Units: Hertz (Hz)/ kilohertz (kHz)
1kHz = 1000 Hz
Ex: vibration that repeats itself 100 cycles per second is called 100 Hz pure tone.
Frequency range of audibility for humans is 20-20,000 Hz
Period (and units; also converting s and ms) - Answers Time that it takes to complete one cycle
Units: Seconds (s), Milliseconds (ms)
1 ms = .001s
, T = 1/f or f = 1/T
Period may be converted from seconds (s) to milliseconds (ms):
s * 1000 = ms
Starting phase (and position re cycle/circle) - Answers Where a vibration starts in it's cycle is called
starting phase, e.g., 90, 180, 270 degree starting phases
One complete cycle can be represented as angles round a circle
Sound can be cancelled out if the condensation points were met by an equal rarefaction point
(displacement would be 0)
Amplitude (peak, peak to peak, rms) - Answers Amount of displacement
How far an object moves back and forth and/or the amount of maximum and minimum air pressure
created.
magnitude of a sound (larger the magnitude, higher the amplitude)
Amount of displacement
(expressed in units of displacement, intensity, or pressure)
rms= .707 x Peak
RMS (root-mean-squared)
-Square each of the instantaneous amplitudes to eliminate any negative values
-Average the squared values
Acoustics - Answers Properties of sounds as they travel in air and how they are affected by objects in
their environment
Waveform (time domain) - Answers When the pattern of movement is displayed with amplitude as a
function of time
Condensation - Answers Increased density of air molecules, corresponds with an increase in sound
pressure
Rarefaction - Answers Decreased density of air molecules, corresponds with a decrease in sound
pressure
Simple vibrations - Answers Also called "pure tones"
Characterized by their physical (acoustic) dimensions of frequency, amplitude, and starting phase.
Pure-tone (sine wave) - Answers "sinusoids"
"Regular repetitive movements"
Relative to phase angle (sin θ)
Sin θ = x/r
Cycle - Answers The pattern of movement as the object goes through its full range of motion one time
One cycle represents the movement of an object from its starting point, to maximum peak, to negative
peak, back to its starting point
Frequency (and units) - Answers How many cycles occur per second
Units: Hertz (Hz)/ kilohertz (kHz)
1kHz = 1000 Hz
Ex: vibration that repeats itself 100 cycles per second is called 100 Hz pure tone.
Frequency range of audibility for humans is 20-20,000 Hz
Period (and units; also converting s and ms) - Answers Time that it takes to complete one cycle
Units: Seconds (s), Milliseconds (ms)
1 ms = .001s
, T = 1/f or f = 1/T
Period may be converted from seconds (s) to milliseconds (ms):
s * 1000 = ms
Starting phase (and position re cycle/circle) - Answers Where a vibration starts in it's cycle is called
starting phase, e.g., 90, 180, 270 degree starting phases
One complete cycle can be represented as angles round a circle
Sound can be cancelled out if the condensation points were met by an equal rarefaction point
(displacement would be 0)
Amplitude (peak, peak to peak, rms) - Answers Amount of displacement
How far an object moves back and forth and/or the amount of maximum and minimum air pressure
created.
magnitude of a sound (larger the magnitude, higher the amplitude)
Amount of displacement
(expressed in units of displacement, intensity, or pressure)
rms= .707 x Peak
RMS (root-mean-squared)
-Square each of the instantaneous amplitudes to eliminate any negative values
-Average the squared values
