A sound's frequency is the number of waves that pass a certain point at a given time.

声音的频率是在给定时间通过某一点的波数。

I'd expected us to have some sort of high-tech device not just stand there and count the number of waves per minute.

我之前还以为要用一些高科技设备呢，没想到只是站在那儿，数每分钟有多少波浪。