Great jazz musicians can play well in any key. For the most part, I believe their key-fluency is tied to their ability to play by ear. They hear something in their heads that they want to play and they play it. The actual key that they're playing in isn't important. Aside from possible fingering issues, there isn't anything that makes one key harder than another if you can play by ear.
You've no doubt experienced some form of key-indifference while singing along to the radio. Assuming a song is within your vocal range, you probably have no trouble matching the pitches you hear. You can probably even sing harmony and scat sing, all without knowing (or caring about) a song's key. And certainly, you've never stopped people from singing a song like Happy Birthday because they were singing in a "tricky" key for you (imagine how they'd respond you did!).
While great players can play well in any key, beginning and otherwise struggling players (myself included) typically favor certain keys more than others. Most often we have a few keys that we're confident in and we totally stumble in the rest. As stated above, I think this inadequacy is tied to our inability to play by ear. Since we can't accurately play our ideas by ear, we depend on some mix of theory, scales, etc., to tell us what to play. And, since we spend most of our time playing in keys with 0-3 sharps or flats, we naturally become more familiar with those scales, patterns, and chords.
To become comfortable in any key, we need to do (at least) two things: 1) We need to work on ear training so we can play what we hear in our heads, and 2) we need to practice playing in the keys that give us problems until they are easy.
I'll be the first to admit that I don't spend enough time practicing in my weak keys. When I practice jazz improvisation, I'll play along to a jazz recording or Aebersold track. In both cases, I tend to spend most of my time playing in keys that I'm already familiar with, simply due to the fact that most tunes are in "easy" keys. There just aren't a bunch of tunes in F# major, for instance.
Aebersold does have several play-a-longs geared toward playing in all keys, but they don't quite give me the workout I'm looking for. For example, I own "Blues In All Keys," "Getting It Together," and "Major & Minor." All of these have entire tracks devoted to single keys or to cycles in all keys, but to me they are really dull play-a-longs. I just don't feel inspired when I put them on. And, while there are some more energetic Aebersold play-a-longs with tunes played in all 12 keys, they typically spend only a single chorus per key. My weak keys go by so quickly that I don’t have enough time to experiment and improve.
For some time now, I've been wishing there was a play-a-long that is both exciting to play with and that has entire tracks devoted to each of the 12 keys. Recently, while playing with "Homestrech" from the Joe Henderson #108 play-a-long (one of my favorites), it suddenly struck me… I can convert any play-a-long track into different keys on my own! How can I do this? Well, I'm glad you asked, because I'm going to tell you all about it.
1. At least one play-a-long track (that you like) in mp3 or wav format.
2. Software that allows you to change the pitch and resave the file.
You'll need to provide your own play-a-long track, but I can help you out on the software end of things. There's a rather powerful multi-platform and open source audio editor called Audacity that you can download and use for free! So, go here to download the software (yes, it's safe). One of the coolest things about this application is that it allows you to change the pitch WITHOUT changing the tempo. Aren't computers awesome!
Note: These instructions apply to Audacity version 1.2.4.
1. After installing the software, start it up and open your play-a-long track (File -> Open).
2. Once the track opens, select all of it by typing Ctrl+A, or you can use the Edit menu (Edit->Select…->Select All).
3. With the entire track selected, go to the Effect menu and select Change Pitch (Effect->Change Pitch…).
4. On the Change Pitch window, set the Pitch: from to the key that the original track is actually in. Then, select the new pitch in the Pitch: to menu. Note: the application doesn't actually know or care about the actual pitch/key that the track is in. This menu simply assigns letters to the transformation to make it easier for you to understand what you're doing.
5. After selecting the Pitch: from and Pitch: to, select up or down. It seems like the results sound better with shorter distances, so select whichever option keeps the distance shorter.
6. Now that you've set Pitch: from, to, up/down, click the OK button. It may take a minute or two for the application to change the pitch.
7. With the pitch changed, you are ready to save the new track. From the File menu, you can Export as WAV… file or Export as MP3…. When you save the file, I suggest you rename it and make the new key evident in the filename.
AUDACITY MP3 EXPORTING
If you do want to export as an MP3, you'll probably need to do the following before exporting (you'll only need to do these steps once).
1. Go back to the Audacity website and download the optional "LAME MP3 Encoder". The link for that should appear on the download page for your operating system.
2. Once you've saved the mp3 encoder to your computer, go to Edit->Preferences… in the Audacity application.
3. At the preferences window, select the File Formats tab. In the MP3 Export Setup section, click Find Library button and select the mp3 encoder that you just downloaded. Lastly, I'd recommend that you increase the Bit Rate to improve the MP3 quality. Something like 192 or 224 should be good.
And that's all there is to it! The above might look complicated, but I assure you it's pretty easy once you give it a try. Audacity also has other effects such as tempo changing (with and without changing the pitch) that you can experiment with as well. I think you'll find that this is a great way to work on your problem keys. Happy pitch shifting!
UPDATE 5/14/2006: 'TRANSCRIBE' SOFTWARE
A couple people have told me about another application that also does pitch and speed altering. It's called "Transcribe" and sells for about $50. Even though Audacity is free, there is one great reason to buy Transcribe: you can modify audio files in real-time! That luxury allows you to simply open a file, set the transposition increment, and press play. To change keys again, just select a different increment. There's no waiting and no need to pre-save files in each key. Click here to purchase or download a free 30-day trial version of Transcribe.