I explain audiation to my students like this:
Audiation is just like transcribing a given external melody or rhythm, only it happens internally.
When you compose music, you are constantly audiating - your "inner ear" "hears" something, you write it down, you check it, and if it matches, you move on, if it doesn't, then you modify your understand of what it is you're hearing until you're satisfied.
You practice audiation the same way you practice your other aural skills, because it is one in the same. I almost think the real question here is How can you develop the inner-ear?
In my experience, I have found that there are two effective ways that yield dramatic results with diligent practice. (Note here that I am not discounting other methods, but am simply describing two that I have found to be effective.)
They are as follows:
And I don't mean writing down a dumb melody in ear-training class. But transcribing pieces of music - especially "non-classical" music to be precise. Often this type of music is in simple or basic duple meter, uses popular chord progressions and intervals, and is transparent in its architecture. Such material is great to work with when transcribing since it does not clutter the aural dictive process.
I recommend that students transcribe songs from their favorite bands - not rap artists as the harmonic language is too sparse, however, it is good for rhythmic training. Transcribing one song in its entirety (voice, guitars, drums, bass, etc,) is equivalent to approximately one year of aural skills at the collegiate level.
Singing is vitally important to developing the ears, though, oddly enough, many vocalists are very poor at sight-singing (that is the subject for another time.) As opposed to transcription, I recommend to my students not to sing popular music for many reasons (not listed here.) Instead, I have them sight-sing using fixed and movable solfege systems through melodic etudes that require them to alter specific pitches within each etude. The alterations are simple at first, eventually graduating to more difficult alterations, modal mixture, and finally atonality or pantonality.
I highly encourage all instrumentalists to sing, and all vocalists to learn rudiments of one melodic instrument. Pairing audiation with kinesthetic coordination creates more neurological connections in the brain, therefore further reinforcing the learned concept.
This is why children's brains are the most active when they play music and why it is such a terrible idea for schools to cut arts funding. But I digress.
Audiation is beneficial for many reasons, some of which are listed below:
- Improves overall musicianship - by practicing audiation, other shortcomings will be improved as well. For example, let's say you're having a hard time slurring some intervals on the trumpet. Your problem could be one of audiation and not actually physical lip technique.
- Reduces Learning Time - you don't need to spend as long learning the notes because you already know the notes and can focus on expressivity.
- Reduces Composition Time - as a composer, this is a big one for me. The better my ears get the less time I spend figuring out what I want, which means I can write or music or do other stuff that I want to do.
- It helps you appreciate music more deeply - think about how much more awesome that Beethoven Sonata or that Radiohead song sounds because you can identify the augmented sixth chords.
- Increases musical memory - you can retain more sounds in your head more accurately for a longer period of time, thus helping you appreciate music more deeply / remember cool things that you want to steal and put in your own music.
- Opens up more opportunities - say you and some friends wanted to do some impromptu barbershop singing at a pub (like me recently) but you can't join in because you can't hear the intervals you're supposed to sing from memory. That makes everyone sad. Incidentally, we sounded great.
- Improves ensemble playing - by being able to hear intervals ahead of time, you are better able to not only compensate for your instrument, but also compensate for the group as well, thus resulting in a better overall sound.
Some composers hear everything instantaneously (Mozart, Mendelssohn) while some labor agonizingly (Beethoven, Brahms, Joan Tower, most people) and some can even work very steadily (Britten, Stravinsky.) One way isn't better than any other way, and it doesn't make the music any more incredible or the composer any more worthwhile. As you can see, I mentioned a bunch of famous composers with wildly different working aesthetics.
What's important is to develop our shortcomings so that we may improve at whatever and however we do what we do - whether it is playing, singing, composing, or just listening.
Hope that helps.