There appears to be a bad interaction between Unity and some Android devices. My Moto X has pretty severe latency, while my Nexus 10 doesn’t.
You can work around the problem by using an Android plugin and playing directly through SoundPool. You can see a video of the effect this has in this youtube video.
The “Android Audio Bypass” demo project is available in source form from github. I found a similar project by Catsknead, packaged up for import, in the forum.
I’ve released an asset that can help with this. It provides access to the native Android audio system for low-latency playback. Also includes PlayMaker support.