Answer is:
Hydrophone
Explanation:
Hydrophone is used to measure sound under water
Answer is:
Coulomb
Explanation:
Coulomb is unit of electric charge
Answer is:
newton second per square meter
Explanation:
newton second per square meter is unit of viscosity
Answer is:
frequency between 20Hz to 20000Hz
Explanation:
frequency between 20Hz to 20000Hz is audible sound frequencies