I am beginner at playing the piano and I want to write my own songs. I know that a song should in some key. My question is - What key should be chosen when writing a particular type of song. What kind of key would suit a sad song and what kind of key would suit a love song ?
It's helpful to distinguish between some different interpretations of the word 'key' here:
If you're referring to the letter name then there's really nothing all that different between the sound of, say, a piece in Eb and that same piece in C#, relatively speaking (at least on modern, equal-tempered instruments—this was not necessarily the case throughout all of history, however I'll spare you the technical discussion as in today's world the use of non-equal temperaments is quite limited). The intervals will be the same, the intervals should be equally consonant or dissonant in any key. There can be some differences on certain instruments, say a cello with open strings which may ring sympathetically in certain keys, or a trumpet, which might sound shrill when transposed to a key that necessitates a higher range, but on the piano these differences will be pretty negligible.
If, instead, you're referring to the tonality of a piece, minor or major for example, then the answer may indeed be yes. We've inherited a great many emotional associations from our culture's long musical history, such as the "minor is sad"/"major is happy" sort of association that most people recognize. It's important to note, though, that the mood of a piece depends on so much more than just its tonality—things like dynamics, tempo, articulation, and so on can elevate or depress a mood totally independent of the piece's tonality. One of my favorite forlorn ballads, Hoagy Carmichael's "Skylark", spends most of its time in a major key, but to my ear expresses a really lovely, heartbreaking kind of sentiment. Conversely, some performances of Arthur Schwartz's "Alone Together" render it very upbeat, despite its predominantly minor key. It's also important to note that these things are really subjective, and one person may get a wholly different perception of a piece than the next.
So to summarize my answer here, there isn't really a clear answer except to say that your job as the composer is to choose a feeling you wish to express and then make other decisions about the music in support of that feeling. Things like the key of a piece are absolutely a part of that decision-making process, and can be informed by our cultural history. Listen to and analyze as much music as you can, trust your ears and your heart, and you'll find some clarity on this point.
Maybe you've found out that songs in minor keys have a 'sad' notion to them, and songs in major keys sound 'happy'. Whilst this can be, and sometimes is, true, bear in mind that every minor key has its relative major - as in Amin. is the relative to Cmaj. Both will have the same underlying harmonies, but Am will centre around a minor feel, whilst C will centre around a more upbeat major feel.
There are also modes available - Dorian and Phrygian both have a saddish tinge to them, whilst Aeolian IS the natural minor.So using these to write a song may well invoke a melancholy feel for some listeners.
But it's not always the case that minor = sad, or vice versa. The lyrics go a very long way, as does the tempo, and even the time signature and rhythm of the melody will obviously add to the sadness or the 'loviness' of a song.
Sometimes, a major 7th chord underlying part of a tune will give that wistful, sad feel. I don't think you are talking about whether Dmin. is 'sadder' than, say Emin. Hope not, 'cos that part of the equation doesn't matter.
Love songs - well, you have to listen to any of the several tens of thousands out there already to find out - there is no magic formula !
no, key is not linked to genre it is linked to TONE which can be manipulated to sound like a certain genre, but songs can be in any key as long as the style in which you play fits the genre.
Just think, ochestras and concert pianists play songs like "Concierto in C" or "Sonata in G#"
So songs can be played in different keys and it doesnt change the genre.
tl;dr it doesnt matter unless it sounds wrong to your ears
For those with perfect pitch, I've heard that keys are like voices, so it probably matters to them. To the rest of us, though, the key matters little.
It's the intervals - Certain intervals add tension, and other intervals release that tension. So, the modes - http://en.wikipedia.org/wiki/Mode_(music) which may all sound weird, except for Ionian, because they all have intervals which you may not be as used to hearing as often.
So, if you want to change the mood in your piece, you might want to move to integrate one of those other modes.
I think definitely yes, for a number of reasons.
on a sonic level, different keys do make a subtle difference. It's subtle, but different keys convey a different subtle mood.
It's difficult for me to say a Key that suits a sad or love song, because there are so many flavours of each. As far as a generic sad key, minor keys are the pat answer.
I would highly recommend listening to Bach's 24 preludes and Fugues, also known as "the well tempered clavier". It's basically one piece in every major and minor key, so it covers the full range of basic tonalities possible. Here's my favourite, in F minor
Briefly getting back to the point about keys conveying a different mood, I can tell when a song is in certain keys, and whether it's a learned association, or something more primal, different keys definitely convey subtly different moods in the sense between major keys(like E and A).
Depending on the type of song there may be certain instruments naturally suited to the style. Some of these instruments may only exist in certain keys, or be difficult to play in others. Someone more experienced will be able to explain further on this but an example is the clarinet, which is most commonly in Bb, and tricky to play in C.(though there is a C version)
Hope that helps :)