A melody should be unique, a “stand-alone,” and sing-able. What grabs the attention of the listener and makes a lasting impression enough so that they are still humming one the piece is over is the melody. So, should melodies be composed directly from singing?
While singing can most certainly aid in the compositional process with finding smooth lines that are easy to replicate vocally, there are some drawbacks.
Believing that melodies should be vocal oriented, “sing-able,” or otherwise logically good according to what a voice can do places a large limit on a composer.
For those that are terrible vocalists (remember, a voice is an instrument like any other – the ability to sing is as inbred as the ability to play the saxophone from birth; hence, it must be learned and developed) they already have the limitation of composing melodies that are constrained by range, intonation, vocal gymnastics, etc.
For trained vocalists, while they can certain accomplish more, they are still limited by what they already know. In other words, the melodies sung are merely a regurgitation of pieces performed in the past that are carved in their vocal muscle memory. And that goes for any instrument, too. Were are parrots, forming variations of music through the skills adapted in pieces we have already learned and played – compromising our originality through the use of an instrument.
So what is one to do.
Composing a melody by just singing ability (or using a single instrument) should be taken with caution. While it can bring up some good ideas, it should never be the primary reliance of writing a piece of music. Intuition, theory, imagination, experimentation, artistry should supplement in the large areas where skills lack in. Only then can a amazing melody be composed.
Just thinking out loud.