Why is it necessary for a classical piece to be written in a certain key?

Question

It seems that each classical piece is written in a specific key, i.e. D minor, or B flat major. Does writing in a certain key enhance the sound of the music? I know this is probably an elementary questions to most classical music lovers, but I have never received an explanation.

Answer 1

Whilst it is correct for you to say that classical music is written in a key, by classical meaning music of the time of Haydn and Mozart, from the early 20th century 'classical ' or 'concert' music wasn't necessarily written with a key signature. Composers experimented with bi-tonality - writing in more than one key at a time (Stravinsky is a good example) and polytonality (Charles Ives) and 'atonality' - writing without reference to tonality at all (the 2nd Viennese school, the Darmstadt school)

As to why composers wrote/write in particular keys, the answer is that different keys have different 'moods' Stirring marches, triumphal music is often written in C major. Minor keys can be tragic (Mozart's D minor piano concerto springs to mind) . Keys are also important in sonata form which (very briefly) involves a subject (in the home key), and 2nd subject usually in the dominant - so a symphony in C major will have its 1st subject in that key and it's 2nd in G major. Then there is a development which may move through a number of keys and a recapitulation when the 2nd subject modulates into the home key. That's a very simple overview and possibly too simple. Whole books have been written on sonata form.

Later: I've been reading the further answers given which, with respect, don't completely answer the question. If the key is chosen because of the instruments etc, why did Mozart write 27 piano concertos in many different keys, yet for basically the same instrumental layout? Haydn, 104 symphonies, ditto? Beethoven surely decided to write his 5th symphony in C minor and his 6th in F major because those keys suited what he wanted to say, not to suit the orchestra.

Answer 2

Actually, it is a good question. Many people with perfect pitch (not me ) say that different keys have different "colours" and by changing the key it alters the whole piece. You and I would just hear a change in key, but some people hear much more than that.
Some will go so far as to say that a piece will only sound "right" in a certain key (or maybe a few keys).

Also,many composers in the past did not give their compositions names so to differentiate they often included the key in the title : violin concerto in A major and violin concerto in D minor.
You can't call them all just "violin concertos "

Answer 3

I'll just add a personal and not very complete note: I far prefer to sing something written in E flat to something written in E ..... it seems to have a certain grace ... although the scientific reason escapes me, as perhaps it should ....

another "shady" contribution on this subj: for piano music, it is best to set a piece in a key which is not awkward to play ... I am not a particularly accomplished pianist, so I prefer not to challenge myself when there is so much else to choose .... I don't subscribe to the theory that "harder is better" ....

Q: I wonder what this might have to do with chamber music? Maybe it would be awkward to consider just one of the instruments ... and then the others might be pushed to the side, or into an uncomfortable spot...so to pick a key that is pleasant for all ???

Answer 4

In addition to glinzek's good answer, another consideration would be the instrumentation or voice part for which the composition is originally intended. You would want your piece played or sung, so making it accessible helps.

In the Baroque, brass instruments did not have valves (neither piston nor rotary). So if you wanted to use horns or trumpets, you needed to write in a playable key. Florid brass parts would have needed to be written in the higher range of the instrument in order to make use of the overtone series which has the notes closely spaced. Horns had "crooks" which changed the key of the instrument, but they still had to rely on the overtones. Later in the Baroque, instruments began to evolve and the technique of "hand-stopping" allowed the horns to play more melodically.

The woodwinds came in a variety of keys, so these need to be considered as well. Even today we have instruments in E-flat and B-flat, F, C, etc. So if you do not want your instrumentalists to be pairing your name with vulgarities, you would probably stay away from keys that required more than 3-4 auxillary fingerings. When considering strings, double- and triple-stops, and open string notes may influence the key.

Vocally, composers who are familiar with the workings of human vocal chords may stay away from keys which have a tendancy to require frequent notes in the "break" of voices. So composers may move up (or down) to avoid, for example, a lot of 4th-line Ds in the soprano.

One additional set of reasons may be for political, social or religious symbolism. For example, many composers wrote in the keys of E-flat Major and C minor (3 flats). Three flats were used by those in Protestant religions to symbolize the Christian idea of the trinity, and Mozart used the 3-flat key signature as a signal of his Free-Mason ties.

Answer 5

There are two primary reasons a piece is in a certain key, 1) the composer originally conceived it in that key, and 2) reasons of instrumentation : (a) range , (b) transposition issues, (c) facility.

Musician, published composer, teacher.

Answer 6

A composer picks a certain key for a number of different reasons. One reason is that is the key that he/she intitially heard the piece in his/her inner ear. Another reason would be, especially for pianistic composers, that that is the key they used when improvising the initial idea. Certain keyboard figures are simply more playable in one key versus another.

In writing for ensembles, consideration must be given for the range of the instruments involved, and t take advantage of each instrument's character in their most effective range. The most obvious is writing for voices. Woodwinds change their character radically in different ranges, most notably the clarinet, which can sound like three different instruments depending on the register used.

Consider the strings, which are tuned in 4ths and 5hs E,A,D,G for the basses, C,G,D,A for cellos and violas and G,D,A,E for violins. So their resonances are best taken advantage of in those keys or keys which feature those notes prominently.

I don't adhere to the idea that cetain keys have certain moods. Back in the days of just intonation that would have been true, perhaps, but today with the use of equal temperment, I don't see how a case can be built for that.

Interesting note that I had never really thought of (I'm a pianist, and don't think of temperment as much as other intrumentalists). In talking to a violinist with the local symphony, he related to me that he found it difficult to switch from playing with a string quartet to playing with a trio (violin, cello, and piano) because string players have to change their intonation when playing with a piano, versus playing just with other string players. Makes sense once you think about it.

Answer 7

indeed it is..usually,if u want to produce a vry bright sound for ur music, u can write it in the keys which is written in sharps..if flats it will give it a more thick n warm sound..and certain pieces are being written in certain keys are for because of transposing instrument..composers have to cater for transposing instruments such as trumpets,french horns, clarinets and others..so to make every instrument logical to play in around the same difficulty, they give certain keys.