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. Duration: 00:31.
An electrocardiogram beep when the heart beats at 60 Hz Or 60 beats per minute. The resting heart rate is 60 to 80 beats per minute. Learn how to make the sound effects of a heartbeat: www.libertivi.com/lelabodubruiteur_100. Duration: 00:09.