Not everybody gets the same set of boundaries applied to them. It would have been a different matter all together if you had said that Doug had schooled you ... the way Rick had schooled him ... the way that Father Flanagan had schooled Rick (with a right cross IIRC).
That Interactive Frequency Chart that Gonad posted has the
Fletcher-Munson curve posted on it which needs to be considered when audibility of a 15 KHz tone is being tested at low volumes.
Unfortunately for me my hearing takes a hit right where it's suppose to be most sensitive around 4 KHz. The
Harmon How to Listen Software demonstrated that I am able to discern various EQ applications so I feel okay with trusting my hearing to a certain degree.
You might have missed the release of that software. I thought you might like it.