The dynamic heartbeat speeds up and gets louder the closer the player is to an enemy. As with the other repetitive effects in the game, it was important that there be enough variation to avoid the distracting 'machine gun' effect that occurs when a sample is repeated multiple times in near succession. Using separate loops for each heartbeat speed would not have achieved this unless the loops were quite long. Instead each of the two heart valves has it's own set of samples, with more than twenty different samples used to create the four different speeds. The volume is controlled dynamically based on configuration settings. Ultimately this maximized variation while conserving memory resources.
A lot of thought went into the sound of the redcoats tapping the barrel of their guns because it occurs so frequently it becomes part of the ambient sound. It also serves as an aural cue to the player as to the proximity of redcoats off screen. Because there are often more than one redcoat in the vicinity of the player, it was important that there be plenty of variation so that it not grow tiring or mechanical.
Again, the sampled instrument approach was applied:
This proved to be an effective approach, yielding a sound that adds suspense and holds up well to the frequent use.
As with many of the sounds in the game, with the aim of creating as natural an effect as possible, footsteps were conceived as mini-sampled instruments. Player character footsteps are made up of nine or more separate sounds - for example, three lefts, three rights, two infrequently heard variations and one very rarely heard step to add some surprise - perhaps a slightly louder squeak. The stopping step is another separate variation.
Once again, the trick to this approach is that these sounds should not be so different that they sound unnatural or distracting, but have subtle differences to create an organic overall effect.