method
1.invented sound detector by attaching piezoelectric sensor to the headband-shaped aluminium sheet
2.connected piezoelectric sensor to amplifier and computer for recording
3. preamplifier was wired to the piezoelectric sensor and connected to computer to import the detected sound signal.
4.covered outer glass container's surface with a foam box to reduce noises and the inner surface with sponge to prevent any error from shrimp hitting the glass