Sensor for measuring frequency

Projects General Guidance
8

MrMark:
If the tube is creating audio frequency sounds, which your nominal 300 Hz frequency suggests, this recent thread should be relevant: Arduino pitch detection in realtime (using autocorrelation and peak detection) - Project Guidance - Arduino Forum

The sensor used in this case is an FC-109 amplified electret microphone module or similar.

Thanks MrMark.
I am afraid that these sensors would be sensitive enough to measure small phase shift.
But I will give it a try.
Do you have a sample code (simple) for sampling data and finding frequency?

Thanks.

Z