Now that we know there are 7 fundamental notes defined keeping one note as a standard reference (A4 @ 440Hz). We can derive all other notes from this. Its important to remember and understand two interchangeable terms in the context of notes that are 1. Tone/Semi-tone & 2. Full-Step/Half-Step. Let Us first look at the note name we know: starting from A they are, A-B-C-D-E-F-G then back to A but one octave higher.
The term used to represent the intermediate notes between two adjacent notes is called a semi-tone or a half-step. Lets understand this.
From A to B its a distance of ONE TONE or ONE FULL STEP.
Between A & B is a note which is higher (of course) than A and written as A# and read as A Sharp, naturally it is also equivalent to a one semitone or one half step higher than A or Lower than B which is denoted as B♭ and read as B flat.
All the note pairs EXCEPT E-F and B-C have one intermediate notes between them.
If we understand the above three rules we can quickly arrive & appreciate the diagram below. Undoubtedly this single diagram is the CORE FUNDAMENTAL of Music.
We immediately note following facts about notes as we study this diagram:
- There are a total of 12 notes
- There is a total of 12 half step or 12 semitone distance between one note & its octave
- There is no intermediate note between E & F and B & C
- E & F and B & C are one semitone apart or one half step apart
These rules MUST be kept in mind FOREVER.