When starting this project, I knew it would be important to develop a sound pallet that complemented the organic, hand-drawn nature of the artwork and also reflected the historical nature of the game. To accomplish this I decided the sound effects should include custom foley, using historically appropriate sound sources, whenever possible. I also wanted to apply my understanding of how sampled versions of acoustic musical instruments work to implement an audio engine that would help create a natural, organic sound.
These considerations led me to the following approach:
a) When appropriate, use realistic sound sources. I collected various leather-soled shoes from thrift stores. I acquired flint and strikers to create the sound of lighting flames. Living in Arlington, MA, right on Paul Revere's path didn't hurt. I recorded bird and cricket sounds during the appropriate season for ambiences. I recorded participants in the annual reenactment of Revere's ride. As game development moves on, I hope to record effects and impulse responses in some of the historical buildings that are present in the game, such as Paul Revere's house, and to work with local re-enactors to record clothing and equipment sounds.
b) Since the characters are children and many of the 'weapons' are toys - e.g., wooden swords, jacks, tin whistles, yoyos - I decided that vintage toys would make a great motif for the sound effects. I proceeded to collect various toys from old-timey five-and-dime stores I found in the area. For example, tops and other spinning toys are used as the basis for a runaway carriage; Joseph's wooden toy sword is just that; a hollow tube that makes noise when you swing it in the air is heard when reaching a checkpoint.
c) As with a good sampled musical instrument, I built a sound effect engine that incorporates a degree of controlled randomness to help create a natural soundscape. This meant that some of the effects required recording many subtle variations. The trick to this approach is that the sounds should not be so different as to become unnatural or distracting, but that there be enough variety so they don't sound mechanical on multiple repetitions.