Are there better option for a smaller file size than .aiff to be used with AVAudioPlayer?

Question

I'm using AVAudioPlayer to play a short one or two syllables word in my app. Currently there are 250 .aiff files and each of the file is roughly 88KB to 125KB each. Currently my ipa file is at 29Megs and I am trying to find the best way to reduce the size so user don't have to have a wifi to download it.

Each of the sound clip is 1 to 2.5 seconds long. I don't need to pause, rewind, fast forward etc.

Based on what I read so far AVAudioPlayer only play aiff, wav or caf and none of those are compressed. Any recommendation on what I can do? Thank you.