Exam 2 SPA 3030
What is an equivalent expression of the following: 10^-1 (Note: an exponent is designated using the carrot "^" symbol).
0.1
Solve for the following: log (8/4).
0.3
Solve for the following: log (12/3).
0.6
What is the correct scientific notation expression for a sound with a pressure of 1,600,000 micropascals? (Note: an exponent is designated using the carrot "^" symbol)
1.6 x 10^6
How much softer is a 2 watts/m^2 sound than a 3 watts/m^2 sound?
1.76 dB softer
A sound source of 98 dB SPL and one of 95 dB SPL are added together. How loud is the resulting sound, rounded to the nearest dB SPL?
100 dB SPL
What is an equivalent expression of the following: 10^3 (Note: an exponent is designated using the carrot "^" symbol).
1000
What is the reference point for sound power that is roughly equivalent to the weakest sound a human ear can detect?
10^-12 w/m^2
What is the dB IL of a sound that is 3 watts/m^2?
125 dB IL
What is the antilog of 2.1?
125.9
What is the dB IL of a sound that is 22 watts/m^2?
133 dB IL
What is the antilog of 1.2?
15.85
What is the dB SPL of a sound that is 175 µPa? When calculating, round to the third significant digit when necessary.
18.8 dB SPL
What is the base 10 log of 150, rounded to the third significant digit?
2.18
What is the base 10 log of 225, rounded to the third significant digit?
2.352
How many newtons of force are needed to create a pressure wave equivalent to the softest audible sound the human ear can hear?
20 Newtons
How many dB softer is a 450 µPa sound than a 4500 µPa sound? When calculating, be sure to round to the third significant digit.
20 dB softer
What is the reference point for sound pressure that is roughly equivalent to the weakest sound a human ear can detect?
20 µPa
How many dB louder is a 4500 µPa sound than a 200 µPa sound? When calculating, be sure to round to the third significant digit.
27 dB louder
What is the answer to the following problem, using scientific notation: 0.006 - 0.003? (Note: an exponent is designated using the carrot "^" symbol)
3 x 10 ^-3
What is the correct scientific notation expression for a sound with a pressure of 30,000 micropascals? (Note: an exponent is designated using the carrot "^" symbol)
3 x 10^4
Solve for the following: log (15 x 100).
3.18
With each doubling of distance from a sound source, how large does the area that holds the pressure wave become?
4 times as large
Solve for the following: log (10 x 1500).
4.18
How much louder is a 4 watts/m^2 sound than a 1.25 watts/m^2 sound?
5.05 dB louder
What is the answer to the following problem, using scientific notation: 0.0005 + 0.0002? (Note: an exponent is designated using the carrot "^" symbol)
7 x 10^-4
A sound source of 78 dB SPL and one of 72 dB SPL are added together. How loud is the resulting sound, rounded to the nearest dB SPL?
79 dB SPL
What is the dB SPL of a sound that is 60 µPa? When calculating, round to the third significant digit when necessary.
9.54 dB SPL
Sound power is expressed in what decibel units?
Decibels intensity level (dB IL)
Sound pressure is expressed in what decibel units?
Decibels sensation level (dB SPL)
Human hearing is linear, and therefore we measure it using a logarithmic scale.
FALSE
Natural logs are the same as base 10 logs.
FALSE
In this formula, dB IL= 10 log W o /W R, what does "W o" represent?
Power Output
In this formula, dB SPL = 20 log P o /P R, what does "P o" represent?
Pressure Output
Human hearing is nonlinear, and therefore we measure it using a logarithmic scale.
TRUE
Natural logs have a base of about 2.72.
TRUE
True or false? You can solve decibel problems given any reference and output.
TRUE
True or false? dB IL = dB SPL
TRUE
What is the dB IL loss for each doubling of distance from a sound source?
There is a loss of 6 dB
What is the unit of measurement for sound power?
Watts per meters squared (w/m^2)
What is the basic formula for solving any sound power problem?
dB IL = 10 log (W O/ W R)
What is the formula for calculating sound power in decibels, given the output of the sound generator?
dB IL = 10 log (W o/ 10 ^− 12 w / m ^2)
What is the formula for calculating sound pressure in decibels, given the output of the sound generator?
dB SPL = 20 log (P o/ 20 µPa)
What is the basic formula for solving any sound pressure problem?
dB SPL = 20 log (P o/ P R)
