  A cylindrical pipe with closed ends and with a partition in-between exhibits
acoustic modes in the two, thus formed, one-dimensional cavities at certain
frequencies. A partial transmission through the partition leads to interaction
between the two cavities' modes and to multiple avoided crossings between
modes' frequencies as a function of the partition position. This is analogous
to a quantum system that has two multi-level and interacting sub-systems and
thus exhibits multiple avoided crossings. Such an acoustic analog is realized
and studied by measuring the sound transmission as a function of frequency
through a pipe with a partially transmitting and movable partition. An
excellent agreement is obtained between the experimental results and a simple
model based on sound wave transmission and reflection at different interfaces.
