Several beeps of an active sonar. This is a low frequency sonar (long range but low definition). It is a triangular wave of 1030 Hz frequency easy to put in loop. In reality, a military submarine usually has passive sonar, more sonar info: en.wikipedia.org/wiki/Sonar. UCS Category: BOATSub. Duration: 00:31.
Cries of a little bat found on the ground :'( Bats use ultrasound to move and hunt, but they also shout in some cases. UCS Category: ANMLBat. Duration: 00:13.
Lower deck in front of a boat. This is the ferry between Royan and the Pointe de Grave. Near Bordeaux, France. UCS Category: BOATShip. Duration: 01:45.
Two helicopters landing and taking off one after the other. Sound recording during the open day of the UIISCI in Nogent-le-Rotrou in France. UCS Category: AEROHeli. Duration: 02:52.