Following sound files from sources downloaded from freesound.org:

62912_Benboncan_Heartbeat_Mono_shortloop.wav
Source: 62912_Benboncan_Heartbeat_Mono.wav
Author: Benboncan

The work is licensed under a Creative Commons Sampling Plus 1.0 License. 

http://creativecommons.org/licenses/sampling+/1.0/