During most of the development process, Leila was a silent game. Android has some pretty easy-to-use interfaces for sound, and I had added support into the game engine for playing background music for a scene, and for attaching sounds to objects, but there were no actual sounds. My suspicion was that most people would play a game on a mobile device with the sound turned down anyway, but it felt right that there should be some kind of audio component.
To make the sounds I required, I used two main sources:
Freesound is a fantastic online resource for user-created sound files of pretty much anything you can think of. A lot of the sounds on there are uploaded under a Creative Commons licence, meaning that you are free to use them, without attribution, for any purpose you like - including using them in a commercial game.
Sounds that were difficult to produce myself, such as the noise of the bus engine and brakes, were all sourced from Freesound.
I wanted the sounds in the game to be inkeeping with the homemade feel, so I decided to make recordings using real-world objects for a lot of the sounds. So, when you hear the doors in Leila's house opening and closing, that's just one of the doors in my flat. And the confirmation sound that plays when you select something from a menu - it's just the sound of me flicking a wine glass!
I was lucky enough to have access to a Tascam recorder to make the recordings, but you could probably do almost as well by recording them on a mobile phone or similar.