Intervals of the C Major Scale
I've posted before about intervals and being able to distinguish both the type and quality of distances between notes, but I wanted to draw out a physical representation of how interval qualities change depending on the letter names we decide to choose. The same sounding interval can be called 2 different quality types.
For example, the distance between C to E and C to Fb will sound exactly the same. On a piano, you will be pressing the same two keys. E and Fb are enharmonic equivalents (the same note with more than one letter name), but C to E is a different named interval than C to Fb. C to E will be a Major 3rd and C to Fb will be a diminished 4. Check out all the piano diagrams below to see how other interval qualities and types can be affected depending on the chosen letter names.