The best definition of musical keys I can give is a preset range of pitch-settings for music. Another definition from dictionary.com is "the principal tonality of a composition." This definition is partly true, but it seems to indicate that the written key is itself part of the composition, which it is not. (All the Classical musicians are walking out on this class right now.) The opening paragraph of Wikipedia's entry on Musical Keys confirms my view that the concept can be a slippery one.
There are two things about keys I want to make absolutely clear: 1) a key is nothing more than a pitch-setting, and 2) a song's "key" has absolutely nothing to with the constitution of the song itself. This is easily demonstrated in that you can play a given song in any one of the 12 keys and it will still be the same song.
I know what you're thinking. If it doesn't matter what key you play a song in, why don't we just play everything in the same key, (C would be nice,) and save ourselves all the headaches?
There are several reasons why songs are written in particular keys. One is the varying tonal character that keys possess on different instruments. On the guitar, for instance, C sounds bland, E sounds bright, and G sounds rich and full. This phenomenon has to do with the tuning of the strings and the positions of the individual notes within the chord. It has nothing to do with the properties of the keys themselves, though it has given rise to the myth that keys intrinsically possess certain tonal characters.
Another reason songs are written in particular keys has to do with the song's melodic range. In general, this range can be described as falling into one of three categories: above tonic, below tonic, and tonic-centric. If the melody is mainly above the primary tonic, the song is above tonic. Songs like this tend to be written in the D-F range. If the melody is mainly below the primary tonic, the song is below tonic. Songs like this tend to be written in the Bb-D range. If the melody is distributed pretty evenly on both sides of the tonic, the song is tonic-centric. Songs like this tend to be written in the F-Bb range. Of course, there are many exceptions. This is merely an observation to help you understand the logic behind keys.
|Melodic Range||Common Keys||Example|
|Above Tonic||D-F||How Deep The Father's Love|
|Below Tonic||Bb-D||Pour My Love On You|
|Tonic Centric||F-Bb||Shine, Jesus, Shine|
For now, I just want to make sure you're comfortable with the idea of a key as a pitch-setting. The bottom line is that the key should be slave to the song, not the song to the key. You're the pianist, and you're in charge: there is no need to be bullied around by a bunch of shrimpy little sharps and flats. Next week (if I'm able to post) we'll develop this concept further and give you the knowledge and confidence to take charge and do a good job.