First, let me say that the response to EarMachine has been overwhelming, and inspiring for us. Thank you to all of our early adopters -- keep the feedback coming!
By far, the #1 question that we have gotten so far is: "Can I get this app for my Android device?"
Regrettably the answer to that is no. We'd love to develop a version of EarMachine for Android (as would any hearing app developer), but there is a significant limitation in their operating system: latency.
So, you may ask: what is latency? Think of it this way. The direct sound that comes from a talker's mouth might reach your ears at time X. The same sound, processed by the app will reach your ears at time Y. The latency then is just the difference between Y and X, and you want that difference to be as close to 0 as possible.
It is generally thought that latency below about 30 ms is acceptable for a hearing app (this value is somewhat controversial). Such latencies are achievable with most iOS devices. On the other hand, the latencies on Android devices are way longer. Just last week I did a test with a friend who had just bought the newest generation Nexus tablet. Using PD and a specialized patch to measure latency, we were measuring values up to 400 ms! This means that the app-processed sound reaches your ears roughly 1-2 syllables too late -- making a hearing app impossible. The experience is kind of like watching TV when the audio is way off.
So, you might ask, is all hope lost? Certainly not.
First of all Google, knows this is a problem. At the last Google I/O conference, they gave a nice (and highly-technical) talk on their work to solve the latency problem. The result was that on some devices they seemed to solve the output (but not input) latency problem -- creating a useable synthesizer app, but not a hearing app. They said that an input latency fix is in the works.
Separately, a clever music tech company, Sonoma Wire Works, created their own build of Android and solved the latency fix themselves -- winning them a best of show award at the 2013 NAMM conference last January. They claim to be in negotiations with some of the Android manufacturers, but I am not aware of any progress on that front.
You can be sure that Ear Machine will develop for Android once these issues are sorted out. In the meantime, let us know if you have found any hearing apps for Android that have acceptable latency!