Question

Using a 20-log decibel calculation and assuming a loudspeaker is generating 80 dB SPL at a distance of 22 feet (7 m) from the source, what would the level be at 88 feet (27 m) away?

Answer 1

To find the sound intensity level at 88 feet given an 80 dB SPL at 22 feet, you subtract 12 dB from the original level due to the distance quadrupling, resulting in a level of 68 dB SPL.

Step-by-step explanation:

The student is asking about calculating the sound intensity level at a different distance using the 20-log decibel calculation. Given that the loudspeaker generates 80 dB SPL at 22 feet, we have to calculate the level at 88 feet. The sound intensity level is inversely proportional to the square of the distance, so if the distance is quadrupled (from 22 feet to 88 feet), the sound intensity level will drop by 12 dB (6 dB for doubling the distance and an additional 6 dB for doubling it again). Therefore, the level at 88 feet would be 80 dB - 12 dB = 68 dB SPL.