Montanero....for a SAR event, older individuals will have different hearing frequencies than kids, so would include a variety of age group

might include a directional vs. omni comparison, N-S-E-W

uphill vs. downhill

wooded area vs. open (I suspect frequency will have an impact)

orientation of the air exhaust port... most whistles are blown with the exhaust port vertical, might try lowering head to get the exhaust horizontal

I know most northerners don't recommend a traditional brass whistle with pea trill,... but I've broken several plastic ones...

I have some hearing loss in the 4000Hz range, but I perceive a brass referee style whistle to be "louder" than my 3 chamber TOPS and the mini Fox in an AMK kit...

appreciate your test...