Key Signatures, And Why We Should Care
This post really pertains only to the 18th century western-classical, and modern western music style. Because this music is so thoroughly grounded in a particular tuning system that relies on different musical “keys,” to work. The pattern of pitch changes in a major scale (the whole-steps and half-steps / tones and semitones), are going to be the same distance regardless of which key you are in.
So what is “a key?” Not like the physical piano key, but a theoretical key that organizes 12 potential different pitches into a structured, stable sounding group of notes. So in the vast majority of western-style music, we have 12 different major and minor keys (although a few are kind of the same which are en-harmonics, we won’t get into that right now). These different “keys” in their most simple form, the same pattern of tones / steps using a different combination of these 12 different pitches.
We should care about keys because they help to organize our musical expression. Certain keys bring a different quality or “feel” to the sound of a melody or chord progression. Understanding these keys can help immensely with understanding music as a whole, as well as sight reading, practice, performance, and improvisation. When I first start talking to a student about theory, keys and key signatures are usually the first thing we go over.
To actually answer the question, a key signature, is used in written music to label the sharps or flats needed for a particular key to maintain their pattern of tones / steps. This is a very short description of a very broad topic, but hopefully at least somewhere to start!
DISCLAIMER
I am not a medical doctor. These posts are all anecdotal, based on experiences through my own learning, understanding and teaching. My musical knowledge is based primarily in the Western classical tradition, which by no means defines the only perspective to learn and understand music.
