ACOUSTICS Flashcards
What do you measure velocity of sound in?
Ft/sec
Symbol for coefficient of absorption
Lowercase a
Symbol for wavelength
Lowercase w
Symbol for power
Uppercase W
What is amplification?
Increased intensity of sound by mechanical or electrical means
What is articulation index?
A measure of speech intelligibility calculated from the number of words read from a selected list that are understood by an audience.
What is a low articulation index and what is the desired situation?
0.15 or less, for privacy
What is a high articulation index and what is the desired situation?
Above 6.0 is desired for good communication
Attenuation
The reduction of sound
Decibel - definition and formula
10 times the common logarithm of a the ratio to a reference quantity of the same kind, such as power, intensity, or energy density. … Often the unit of sound intensity in this formula:
IL = 10*log(I/Io)
Symbol and measure for sound intensity
Capital I… W/cm squared
Symbol for minimum sound intensity audible to the average human ear
Io … 10 to the negative 16’s W/cm squared
Symbol and measure for sound intensity level
IL measured in dB
Symbol and measure for noise reduction
NR …dB
Symbol and measure for acoustic power
P … W
Symbol and measure for area of barrier or component between rooms
S … Feet squared
Symbol and measure for coefficient of transmission
t
Symbol and measure for total acoustical absorption
A … Sabins
dBA
The unit of sound intensity measurement that is weighted to account for the response of the human ear to various frequencies
Frequency
The number of pressure fluctuations recycles occurring in one second, expressed in hertz (Hz)
Hertz
The unit of frequency; one cycle per second equals one hertz
Impact insulation class (IIC)
A single number rating of a floor-ceilings impact sound transmission performance at various frequencies
Intensity
The amount of sound energy per second across a unit area
Intensity level
10 times the common logarithm of the ratio of a sound intensity to a reference intensity… The formula for decibel describes this