<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> I am kind of a newbie, so if this topic is a dead horse that's already been beaten a few times, forgive me. What I would like to do is briefly describe my understanding of stretch and ask for comments about whether I am getting the idea or not. Randy Potter states the following: "We are simply trying to match our tuning to the amount of inharmonicity in the piano". (Randy Potter course book, section 1.6). "You do not put any stretch in the piano. The piano told you how much to stretch it. ... using 17ths and 3: and 4: octave tests, you would end up with a perfectly stretched piano". (section 1.7)  What he is saying is, minimize octave beating, and then a piano is stretched correctly. Well, recently I bought the Reyburn Cyber Tuner, which has a "Octave Tuning Style" feature, which gives the user a range of 9 levels of stretch you can choose from; "1" being "pure" (beat speed for the 4:2 octave at A2-A4 = 0), and "9" (beat speed = 0.8/sec.) I was immediately confused because this contradicts Potter, who says a piano is tuned "right" when octave beating is minimized, period. Meanwhile, I can remember a physics professor explaining that human hearing is "imperfect" because when we hear a pure octave, we think it's a little bit narrow, so pianos are stretched in order to make octaves sound more correct to the human ear. No one has ever explained all this to me succinctly. What I have concluded in my own little pea-brain is that there are two distinct kinds of stretch: what I will call "objective" and "subjective". The objective stretch is that which compensates for a piano's inharmonicity. The subjective stretch is the amount beyond the objective part, which makes it sound good to the listener. So when people use the word "stretch", they're not always talking about the same thing; sometimes they mean the objective part of it, sometimes they mean the subjective part of it, sometimes they mean both parts, and sometimes they don't know what they're talking about. Right ?? Any guidance on this subject is welcome.        </html>