Apps

If you're walking around with a smartphone, or have an app simulator on your computer, such as BlueStacks, there are many apps that are useful for ear training and for checking your AP and relative pitch progress. Below I will list a few that I have found recently and what they do - all of the ones I list are free:

Pitch Perfect:   this is basically a virtual pitch pipe that lets you check notes against what you are hearing on the radio for example (or what you have in your head), or really any sound that you hear where you want to check the note, and it also has a 'notes' section where you can play a wide chromatic range of notes, and it gives you the Hz numbers. It also has a 'key signatures' page if you forget how to notate which is pretty nice.

Absolute Pitch for Piano: This is a challenging app that will test both your perfect pitch and relative pitch, because it plays a series of notes, ranging in difficulty. You don't need perfect pitch to play the game, because if you get the series of notes wrong, it will play it again, and then you can use your relative pitch. There is a 'guitar' version as well, called Absolute Pitch for Guitar.

Perfect Pitch Practice: This one plays individual notes and has you choose what they are, grading you out of 10 notes. You can choose from different note ranges, but if you're really testing yourself, just do the last level because it  tests you on a full range of notes. In practice, this is testing both AP and relative pitch but it is a good and simple app.

Perfect Chord for Piano: I was looking for an app that would test chord hearing for AP, and this guy made it. You can choose a range of difficulty, and again this will test both AP and relative pitch pretty well. You will have to recognize 7th chords and all their inversions, which is a good test. There is also a version for guitar, Perfect Chord for Guitar. In that one it shows a virtual guitar neck and you choose which notes were played in the chord. Some of the chords aren't physically playable in that position (if you were to try it on the guitar), but of course it still works to test you on the notes. It's also good for testing your relative pitch hearing of inversions.

Anyway I hope you are able to try some of these out - I wish I had discovered them earlier! I would certainly still encourage Burge style meditation listening techniques at least every few days, but I think these apps are a really good supplement to test your AP progress and improve your relative pitch as well. Overall, I think they will help accelerate your ear training progress. There are also a number of paid apps that are available, but I haven't tested them so I can't speak to their quality. Of course you probably want to keep things as musical as possible, so learning songs and solos by ear is great for your ear and musicality. Programs like Transcribe are really nice for that as you can slow things down/loop them, etc. and it also lets you slow down video which is cool.