A quality scientific experiment needs to control variables. Whether one is measuring TNF or using a vibration meter at 60 hz, you are measuring a frequency, vibration or oscillation of a tapered tube after putting it into motion, either by flexing it or testing its resonance via a speaker. A variety of factors will influence the outcome -- blank materials, modulus, wall thickness, blank diameter, length, etc.

At a randomly chosen point down from the tip, you are measuring the vibration, a manifestation of frequency, of the tapered tube at a particular point or length, and you are measuring it in the butt. In fact, as proven for years in golf shafts, to get a true flex profile (frequency or vibration of the tube), you would need to measure the frequency or vibration at various points along the tube, as it will change significantly throughout the tube's length, as wall thickness and diameter change, as to flex points.. Of course a flex profile can also be determined by hanging a predetermined weight from the end of the tube or rod. And flex profile is totally determined by the particular design of the rod taper or action. An overall butt stiff rod with a softer tip will recover slower than a rod with a stiffer (higher frequency) tip.

Further, I would question is a rod's sensitivity the highest reason or factor in an angler choosing a rod? Some would state they first desire certain casting characteristics over sensitivity. In addition, one's ability to feel vibrations is going to be a rather individual experience, just as is one's ability to hear certain sounds vs another person, and as is one's visual acuity different than another's. And sensitivity will also be a function of how much line is out from the rod tip.

Further, I would posit that a rod's sensitivity has to be related in some way to the type of line that one is using, as the vibration and casting ability is going to be related to line choice and type.

So this is a very complex polemic.

My experience with fly rods is that what I would call "sensitivity" is certainly affected by the fly line I utilize and its taper and material composition in combination with the rod. There is a synergy, or lack there of.

In terms of controlling variables in this debate of methodologies, I think keeping rod blank diameter and overall weight as constant as possible between various modulus blanks would be appropriate and desirable.

Overall, what I like about this discussion and debate, is to move objective fact finding and correlation to the front and center when it come to rod metrics and evaluation vs reliance on anecdotal human bias, POV and marketing @#$%& .

So, in practical terms, is a Carbon Air 9 foot 5 wt more sensitive than a Gamma Beta of the same size and line weight, or an LMX? Or is it just lighter? Does the Carbon Air's newer, high-tech resin enable it to perform or be designed in better ways than the Gamma Beta or LMX, including sensitivity? How about we measure those two? As that will have a very real effect on my next buying decision.