Adding tones to a known scale is one way to create new sounds. Here's an example of adding a new tone to a known scale to create a new scale...the E blues scale.
In this instance, we are adding the B♭ [♭5] to the E minor Pentatonic scale. When we do this, we create the E Blues scale. The B♭ acts as a passing tone when we are using it for soloing over E minor type progressions. And, this scale can be called E minor blues, since it has a ♭3rd.