> However, the relationship between absolute pitch and frequency isn't always trivial. Not only is it not trivial, it is undefined. For example, "middle C" can

> However, the relationship between absolute pitch and frequency isn't always trivial. Not only is it not trivial, it is undefined. For example, "middle C" can map to different frequencies depending on your tuning system, for just one example. Pitch is the higher level abstraction. Especially on the organ, "middle C" may get interpreted as "middle C plus a C an octave below, plus another octave below for good measure" depending on context. I assume that's what Carpenter is changing when he's putting his hand on those pads where the stops should be.