Chapter 8 Flashcards
Suppose you measure a sound pressure of 400 uPa. What is this value expressed in dB SPL? Round your answer to 3 decimal places.
26.021
If a sound has an amplitude of 100 dB SPL at 1 meter from its source, what will the amplitude (in dB SPL) be when the sound is 4 meters from the source? Round your answer to two decimal places.
87.96
Numerical scale
series of numbers with specific numeric properties (1, 2, 3)
graph scale
size of the divisions of units on a graph axis
measurement scale
a systematic set of measures used to quantify some physical quantity
nominal
eye color (blue, brown, green, hazel)
ordinal
letter grades in a course (A, B, etc)
interval
temperature in celsius
ratio
temperature in kelvin
Only numbers on ___ scales can be meaningfully converted to logarithmic form.
ratio
In the audiogram, a negative value represents hearing thresholds that are ____ than normal, while positive values represents hearing thresholds that are ____ than normal.
better
worse
Suppose you measure a sound, and you find that its level is 0 dB SPL. What is the best interpretation of this value?
The sound has an amplitude of 20 uPa
The sound has an amplitude of zero Pa
The sound has an amplitude less than 20 micropascals.
The measured value is not mathematically possible.
The sound has an amplitude of 20 uPa
A logarithm answers the question, “the base (of the logarithm) raised to what power equals a certain number?” For example, log10(100) = 2 because the base (10) raised to the power of 2 equals 100.
Question: what is log10(100,000)?
5
How many dB SPL is a measured sound pressure of 60 uPa? Round to two decimal points.
9.54
How many dB IL is a measured intensity of 10^-2 watts/m^2?
100
Suppose you are given an acoustic analysis of of speech in noise. From the analysis you know that the SNR is 40 dB and the noise level is 20 dB SPL. What is the signal (speech) level in uPa?
20,000
Suppose you have two loudspeakers that produce identical sounds (same frequency, same amplitude, and perfectly in phase). If the total sound pressure of the two sources individually was 60 dB SPL, what was the sound pressure of the total? (in dB SPL)
63
Suppose you have two loudspeakers. One loudspeaker is the source of a “signal”, with an amplitude of 30 dB IL. The other loudspeaker is a source of “noise”, with an amplitude of 60 dB IL. What is the SNR in dB?
-30
When dB is followed by IL, SPL, HL, or SL, it means that a specific reference (denominator) was used. Match the corresponding reference with each value:
dB IL
dB SPL
dB HL
dB SL
10^-12 W/m^2
20 uPa
-adjusted at each freq using the average human auditory threshold
-adjusted at each freq using an individual’s auditory threshold
How many micropascals (uPa) is a value of 10 dB SPL? Round to two decimal points.
63.25
On a VU meter, 0 dB equals the maximum recording level.
true
If you have a sound with an amplitude of 40 dB SPL, what is the equivalent quantity in uPa?
2,000
If you have a sound with an amplitude of -40 dB SPL, what is the equivalent quantity in micropascals (uPa)?
0.2
A doubling of intensity involves an increase of __ dB IL. A doubling of sound pressure involves an increase of __ dB SPL.
3
6
How many dB SPL is a measured pressure of 10,000 uPa? Round to two decimals.
53.98
Doubling intensity will result in [ans1] dB increase.
3
If the signal of interest level is 75dB and the noise level is 45dB, what is the SNR?
30
If a sound’s amplitude is 70dB SPL at 4 meters from the source, what is the sound’s amplitude 16 meters from the source?
58
