Realistic heartbeat.
The zip includes:
01. Slow heartbeat (loopable) – (0:08)
02. Accelerating heartbeat – (0:06)
03. Fast heartbeat – (0:04)
04. Slow heartbeat (with reverb) – (0:08)
05. Fast heartbeat (with reverb) – (0:04)
You can combine sounds 01, 02, 03 for producing accelerated heartbeat.