Loudness is how strong or weak a sound seems to a listener.
Bigger wave amplitude usually sounds louder.
Showing a random 20 of 50 problems.
Example 1
challenge
Twenty identical incoherent machines each produce 75 dB alone at a worker's ear. What is the combined level? (log10(20)≈1.30.)
Example 2
easy
Two tuning forks vibrate at the same frequency. Fork A swings with 0.4 mm amplitude; fork B swings with 0.1 mm. Which sounds louder?
Example 3
easy
Fill in the blank: The larger a sound wave's ___, the louder it sounds to a listener.
Example 4
medium
A jackhammer is 100 dB and a library is 40 dB. By what factor is the jackhammer's intensity greater? (Each 10 dB is x10.)
Example 5
medium
A whisper has intensity 10−10 W/m2 and a normal conversation 10−6 W/m2. The conversation is louder by how many decibels?
Example 6
easy
True or false: a high-pitched whistle is automatically louder than a low-pitched hum.
Example 7
medium
A sound's amplitude is multiplied by 5. Using I∝A2, by what factor does intensity grow?
Example 8
challenge
A point source gives 70 dB at 1 m. Intensity follows the inverse-square law. What is the dB level at 10 m? (A factor-100 intensity drop is -20 dB.)
Example 9
easy
As you walk away from a speaker, the amplitude reaching you drops. What happens to the loudness?
Example 10
challenge
A point-source siren reads 100 dB at 10 m. Safety guidelines cap continuous exposure at 80 dB. How far away must you stand (inverse-square law)?
Example 11
medium
A sound's amplitude is halved. Using I∝A2, what fraction of the original intensity remains?
Example 12
easy
Rank from quietest to loudest: rustling leaves (20 dB), conversation (60 dB), rock concert (110 dB).
Example 13
medium
A sound's amplitude is tripled. Using I∝A2, by what factor does its intensity grow?
Example 14
hard
A factory hits 90 dB at 5 m from a machine. Using the inverse-square law for a point source, find the level at 50 m.
Example 15
medium
Two identical incoherent speakers each produce intensity I0 at a point. What is the combined intensity, and how many decibels louder is this than one speaker alone?
Example 16
medium
Sound intensity at a point is 1.0 W/m^2 from one speaker. A second identical speaker (incoherent) is added at the same distance. What is the total intensity, and how does loudness change qualitatively?
Example 17
medium
A sound's intensity rises by a factor of 1000. How many decibels did the level increase by? (Each 10 dB is ×10.)
Example 18
medium
Sound A is 40 dB and sound B is 40 dB, played together (incoherent). What is the combined level?
Example 19
medium
A pressure wave's amplitude is 0.2 Pa. A second wave with the same frequency has amplitude 0.6 Pa. How many times more intense is the second?
Example 20
challenge
A sound is 50 dB. To make its intensity 1000 times larger, what dB level is needed? (Each 10 dB is x10.)