Why are different keys necessary / important? [duplicate]

Question

If all major key songs can be played in C major, then why do people play them in other keys? Assume there is no singer involved and we're just talking about what sounds "good". My understanding is that keys just change the pitch of the song. So the only reason is to make the song lower/higher.

So do certain songs sound better when they have a higher (or lower) pitch, is that why people use different keys? If so, can you provide an example of a song that sounds better in one key than the other?

edit: I wasnt aware of the duplicate when I wrote this question. but due to the other ones title, it'll be hard for people to find it. so this has a more search friendly title atleast. thanks for the great answers.

Answer 1

The tonal system is an historical inheritance, but we could not do without it today in the realms of most classical, popular and main stream music, even if we wanted to (and why would we want it?, anyone who decides to play all their life entirely in one key is perfectly free to do so :-)

Now, seriously, there are many reasons why we absolutely need different keys and here are a few I can think of (not including vocal range since singing is excluded from OP's question, and considering the general adoption of equal temperament as that seems to be the implicit assumption of the OP):

1. Instruments. Again for historical, but also physical, reasons, not all instruments are equally easy to play in all keys, or in the same key as one another. Particularly difficult pieces for, say, clarinet, are written in a key that makes life a little easier for the player. If they were written in another key they might not even be playable. So if the clarinet is the focus of the composition, the composer takes that into consideration. Also, for limited range instruments (say, one and a half octave or less), a key must also be chosen that takes into account the range of the instruments being used to play the melody.

2. Timbre. The overall sound of a composition or recording is indeed affected by the chosen key. Play a 1st inversion C major chord and play a 1st inversion G major chord in a piano. The resultant sound is very different (one being much higher in pitch than the other, obviously). When you take that to a whole piece or orchestration the final result may produce different subjective appreciations. Not because one key is inherently somber and the other joyful (or some other nonsense of the kind) but because the sound of each instrument is affected, as is the overall result. This is very relevant in distant keys (say, a 5th apart), but may not be very significant in close keys.

.. Which brings us to...

3. Composer. Like any human beings composers are conditioned by their training and routines. Chopin said that C♯ was the perfect key for the piano, as the alternation of black and white keys are perfect for the shape of the human hand (or something to that effect). Be that as it may, most pianist composers have a tendency to use certain keys, as their hands naturally “finds” that keys when fiddling at the keyboard. Some force themselves to write in a specific key, to get out of such habits and find new musical ideas. Same as with guitarists and chord positions.
   Singer-songwriters compose naturally within their voice range.
   And, generically speaking, composers (or artists, bands, producers) need to take into account all these factors to ensure they get the intended result.

4. Composition (modulation). Not all musical pieces stay in the same key all the time. Life would be very boring, at least for me, if they did - all symphonies and most of jazz would vanish away, just to name a couple of examples.
   Now, we could arbitrarily decide that all music “starts” in C and that when we modulate (a fancy word to say that we change the tonal center) to G major, this is just still C major with a few F♯ here and there. But that wouldn't be much of a gain and it would make it very hard to compose in the tonal harmony tradition (so no Mozart and no Beethoven :-)

Answer 2

Sorry in advance for the long post. Hopefully its worth reading!

The only REAL reasons I can think of why every piece isn't written in, say, C major or C minor, are:

• to accomodate the upper or lower range of some instruments. For example, the lowest note on a violin is G below middle C. A work written in D, for example, can use include that lower G for the IV chords; a piece in B-flat would have to use the E-flat or F ABOVE middle C. Obviously this doesn't usually affect piano music;
• in older music brass instruments could only play certain tones and had to be accomodated with particular keys; Bach often used D major for works featuring brass instruments; and,
• because some works are easier to perform in certain keys. Playing G-F#-E-D on the piano is probably easier than D-flat - C- B-flat - A-flat (one black key vs. three black keys). While Liszt could be enormously complicated to play its amazing how he managed to find the key that makes certain works playable -- if barely; in "Bénédiction de Dieu dans la solitude" from "Harmonies poétiques et religieuses", the F-sharp major key makes it just possible to play the extended chords in the right hand.

So-called transposing instruments currently require other keys - a B-flat clarinet's C sounds the same as a violin's B-flat -- but in a way this is a historical accident rather than a necessity. Other than the fact that you'd be bucking significant history and practice in doing so, you could re-name the B-flat clarinet's "C" as "B-flat" and be done with it.

So why do it? I think it has to do with the composer and their relationship to keys. Mozart used certain keys in certain situations. For example, the E-flat that runs throughout The Magic Flute is, for Mozart, evocative of Free Masonry; the three flats represent the brotherhood ideal. He used G minor for particularly gloomy music; his two minor key symphonies are in G minor. C minor was used for especially dark works like the C minor piano concerto or the C minor piano Fantasy.

Beethoven is well known for his use of the key C minor: the Pathetique and Op. 110 sonatas, the fifth symphony and third piano concertos, the Coriolan Overture.

For many composers flatted keys are used when a mellow or pastoral mood is required. Sharped keys are often more outgoing or brassy (actually can't think of a great word to describe works like the third movement of Mendelsohn's violin concerto which is in E major or the fourth movement of Beethoven's 7th symphony in A major).

At the end of the day you could write a terrifically agitated or a quiet and prayerful work in any key, and even composers who are known for their use of certain keys for certain moods have exceptions -- the incredibly angsty first movement of Beethoven's Kreutzer sonata in A, not C, minor. But composers have remarkably consistent relationships with keys, often for reasons known only to them. Einstein's (no, not THAT Einstein!) "Mozart" has a whole chapter on Mozart's use of keys!

Some of these reasons certains keys are used might be historical -- brassy D major works might reflect the old need to write brass instruments in D major -- but otherwise they're simply one of the quirks that each composer has. Rather than mourn the fact that you need to learn pieces in different keys, use the key as a way to unlock what the composer is trying to say. If you're able to read some of the many articles or book chapters on composers and their keys you'll gain valuable insight into how keys shape meaning for different composers.

And if you ever get around to learning how to improvise in multiple keys, you'll see that you gravitate to certain keys for certain things.

Answer 3

There's little to add to the excellent answers already posted, but I'm not sure the OP has thought much about answering his own question.

All this assumes equal temperament. Just temperament has its own realm.

However, let's take a guitar piece. E major is one of the most popular keys for guitar music, as it gives the opportunity to use open strings as 'bass' notes. Possibly this is what the OP is getting at. Playing the same tune in F maj. will bring many problems, and taking it into Eb even more!

But what about tuning the guitar down a semitone, and playing then. Suddenly the tune's in Eb. But would it actually sound any different, with the open Eb as 'bass' note now? In isolation, I don't believe so, unless the listener had absolute pitch. But even then, what difference if any would that make to the tune?

Then trying to get that same tune played on another instrument - piano, say - will sound different, but probably not so different as in the above example of playing it on guitar with open then with fretted notes.

Other answers have covered the more obvious vocal range, instrument range and ease of playing adequately but the ease of playing will vary from player to player. Yet another reason to have the facility to play in any of the 12 major or 12 minor keys. And the moment anything modulates, it's in another key at least for a moment. So starting in C is only one option.

Answer 4

It's not that they're necessary or not, it's simply the way music works. In order to have the tools I need to give the answer to this question my best shot, I have to start from the beginning, so much of this will be stuff you already know.

Let's assume an equal temperament universe with twelve tones (which is what we have nowadays anyway.)

We know that the pattern T, T, S, T, T, T, S (where T is Tone and S is semitone) will make us a major scale. Let's start by considering a C major scale.

C, D, E, F, G, A, B, C

That's great. Now, using the notes in this set (which happens to be the key of C) we can write the first bar of Twinkle Twinkle Little Star.

C C G G A A G||

Notice also that these notes are the scale degrees

Tonic Tonic Dominant Dominant Submediant Submediant Dominant

But let's try something different. Let's transpose all of the notes in this scale up half a step. We get:

C#, D#, E# (Or F), F#, G#, A#, B# (Or C), C#

The key of C# major. All of the notes are different. But since we moved each of the notes up by the same distance, the pattern of intervals which we observed earlier still holds (T, T, S, T, T, T, S). This is a powerful observation. It means that we can use the same scale degrees to write Twinkle Twinkle Little Star as we did in the key of C. In this case,

C# C# G# G# A# A# G#|

That's not that impressive because they're just a half step apart, but try it in G:

G, A, B, C, D, E, F#, G

Here's the set of notes that is in G. Using the pattern of scale degrees that worked previously in the other keys for Twinkle,

G G D D E E D|

Now, so far, this has all probably been stuff that you already know. It's now time to get into the thrust of the question.

A quick aside here is that we've been assuming equal temperament this whole time, but in the older days, different keys sounded totally different, and some were rendered unplayable in some tunings. In that case, it makes sense that we would have different keys -- different keys sounded totally different. (See:

)

Resuming our place in the equal temperament twelve tone universe which we started, here's a false assumption in your question: "Assume there is no singer involved and we're just talking about what sounds 'good.'"

"What?" you ask. "It's an experimental variable! It's not false, its the premise of the question!"

I think you might be shooting yourself in the foot by excluding that.

Often, what sounds "good" is determined by whether or not there is a singer, and that singer's tessitura, as well as what instruments are playing and keys that they play comfortably in. Other than that, as demonstrated above, the song will be exactly the same, except higher or lower, as you said.

But to play ball with a fingerless world, let's say that we have a magical instrument that is entirely indifferent to keys playing an all instrumental song. Would that song sound better in one key than another? That depends on what you mean by "better." Perhaps you interpret a song require a lower, more thunderous key. Or maybe it sounds better to you played like chirping birds. Either way, you can take advantage of the landscape of the universe of music so that you can play it in exactly the harmonic range you want.

Keys are a natural resource. They exist simply because that's how music works. Skilled musicians can take advantage of them so that they can sing in their range, or create the sensation of chirping birds or a thunder storm.

I hope this is helpful. Good question too!

Answer 5

C major is the hardest scale to play, there are so many opportunities to do a wrong fingering! And you'll never get fluent if you're forever fumbling the fingering!

Apart from considerations of range - and even on piano there's often an optimum position where the chording sounds neither muddy from being too low or tinny from being too high - only the simplest songs stay in one key for long. Notes and chords not in the scale are used momentarily for colour, or the entire key centre may move for a section of the piece. A piece in C major is going to use a LOT of black notes.