“As a free flying paragliding pilot, I have finally built my own simple but effective instrument that plays beep-beep during climb and so on.
It is an instrument used by pilots during flights (sailplane, paraglider, hanglider, balloon, etc.) to help finding the core of the thermals and climb the air more and better.
It is a very sensitive barometer that emits sounds when climb (going up) and also when sinking (going down). Sounds are simple beep-beep, every second, or two per second or more during climb (more climb rate = higher frequency beeps): it is so sensible that it starts beeping just after a few centimeters (!) per second; you may try slowly lifting your arm holding in the hand the Vario to obtain the sound. In case of sinking rate it emits long (continuous) beeeeeeeeps at -1 m/sec or more.”