Question

An observer at some distance from a speaker that emits a steady 100 Hz sound wave hears a tone with a sound level of 21 dB. The speaker is then adjusted to emit a sound wave with the same amplitude as before but at a new frequency of 2000 Hz. If the observer moves to a spot twice as far from the speaker as where she originally stood, what sound level will she hear?

a) 37 dB
b) 39 dB
c) 41 dB
d) 43 dB
e) 45 dB

Answer 1

The observer will hear the tone at a sound level of 15 dB.

Step-by-step explanation:

To determine the sound level at the new distance, we need to use the inverse square law, which states that the intensity of a sound wave decreases by a factor of 4 when the distance from the source is doubled.

Since the sound level is a measure of the logarithm of the intensity, the sound level will decrease by 6 dB when the distance is doubled.

Therefore, the observer will hear the tone at a sound level of 15 dB.