Two identical tuning forks are struck one after the other in a quiet room and a clear waxing–waning of loudness is heard.
(a) Define the term "beats" as used in acoustics.
(b) Explain why beats can be heard only when the frequencies of the two sound sources differ by a small amount.
(c) The two forks in the experiment above produce 10 maxima of loudness in 4 s. One fork is known to vibrate at 256 Hz. State the two possible frequencies of the second fork and justify, in words, which of the two is more likely to be correct if the waxing–waning is observed to be very slow.