[In this extract from Ben Long's The Insider's Guide to Music and Sound for Mobile Games -- a book which is about "the challenges one faces when trying to make a game sound awesome," per the author, he describes the process of working on the audio for Backflip Slots. You can find out more and check out the book at his website, http://www.gameaudio101.com/]
Backflip Slots: When using headphones, we hear most of the sonic spectrum. One challenge of creating audio content for mobile is taking into account the possibility of headphone usage. The iPad allows for a bit more mid-range frequency content, so I considered this when working with Backflip Studios on their HD stuff.
Typically, a mobile game will have a looping background ambience, background music, dialogue and UI/gameplay sounds. For the menu ambience in Backflip Slots, I visited a casino and brought along my Zoom H4 handheld recorder to capture the ambience. Luckily, security didn't ask any questions as I entered the building with this strange little device.
After finding the rows of slots machines, I sat in the middle and started playing. This location gave me a nicely-balanced ambience, so I placed the recorder on the seat next to me and started experimenting with different configurations. All this was done without headphones, so I had to use my best judgment and just go for it.
The funny thing about casinos is that each slot machine plays jingles in the key of C. The result is a hypnotizing cacophony that keeps the players hooked. I have actually played live gigs at casinos before and been instructed to keep every song in the key of C. This is surreal, much like playing alongside a choir of robots!
Since Backflip Slots was getting a more traditional look, we needed the sound to follow suit. For the reel spin, I went for a looping mechanical sound with a subtle friction texture. To achieve this, I combined the sound of a tractor engine with factory machinery samples from my own sound library. The two sounds were then mixed together and combined with elements from Sonic Fiction.
Seamless looping is commonplace in games but often brings technical challenges. That can detract from the creative focus, but it's a necessary evil, given the technical limitations of the hardware platforms. The reel landing sounds needed more of a chunky ‘click' feel that would not be too overbearing.
Each bonus spin-character icon has an animated sequence in which they come to life and jump off the screen. These actions received everything from an 8-bit flamethrower to the sound of a samurai sword being unsheathed.
