Hydrophone performance should be more dynamic and based on a number of factors:
- Above or below a thermal layer
- Sea state
- Salinity and water temperature
- Number of contacts: the more ships traveling in a group (i.e., a convoy) the farther away it should be able to be heard. Conversely, the range at which a lone contact can be picked up should be less than that of a convoy.
- Size of the contact: the large the ship, the more machinery it is running, so the more noise it is going to make.