It's more about putting numbers on those throwaway terms we use so much here. We talk about air flow and how long we can hold a note, but it doesn't really mean that much until we start using real numbers instead of just guessing. A good place to start is to measure the volume of air available to us in our lungs after a big full breathe in.
It took me 15 minutes from deciding to get off my backside and do something to getting a result, so no excuses!
Apparatus is a large bowl, regular shaped non-opaque 8 litre container with a good lid, a couple of feet of plastic tubing, biro, measuring tape and a sink.
Part fill the bowl with tap water. Fully fill the container and seal it excluding as much air as possible. Invert the container in the bowl so the lid is fully submerged and remove the lid. Insert one end of plastic tubing under the rim of the container. Mark the water level of water inside the container.
Now take a BFB and exhale through the tubing into the container until no more will come. Mark the new level of water inside the container. (If this is below the water level in the bowl, remove some water from the bowl. If air has bubbled out from under the container, you need a bigger container). Mark also the water level in the bowl on the container.
The container I used was as near as makes no odds a 20 cm square. The distance between the first and second marks was 9.1 cm
Uncorrected lung volume = 20 x 20 x 9.1 = 3,640 cubic centimetres = 3.64 litres
The difference is minuscule, but just in case there's a smart aleck out there who knows the air is not quite at atmospheric pressure, the difference between mark 2 and mark 3 gives the partial vacuum. -3.6 cm WG in my case and since atmospheric pressure is around 1,020 cm WG, I should correct my result by multiplying by (1,020 - 3.6)/1,020 = 0.9965.
Corrected lung volume = 3.64 x 0.9965 = 3.63 litres
You can correct for temperature as well but the effect is similarly minute and I can't be bothered.
This is pretty much the same sort of kit the medics (used to?) use to measure what they call Vital capacity - Wikipedia, the free encyclopedia.
According to their stats, my result looks okay for a bloke my age (56) though 80 kg and 5'11" isn't a small build and I can't say that I'm overly impressed. Maybe my BFB is just a comfortable playing one rather than a full blown bust-a-gut medical one.
Be interesting to hear others' results.
PS TOP TIP: After you've taken your measurements, tidy up straight away. Your plastic tubing can easily turn into a syphon and flood your wife's kitchen surfaces. Don't ask me how I know this.