Interesting! A club glider had a Rico - I found the sound so irritating that I only flew the glider once.

On Thursday, July 13, 2017 at 3:13:26 PM UTC-4, Jonathan St. Cloud wrote:
That brings back memories, those ticks were easy to hear, to understand and didn't take up so much ambient noise, a short tick has more information than a longish beep or other tones.

On Thursday, July 13, 2017 at 10:25:06 AM UTC-7, wrote:
A TE probe approximates the pitot pressure but subtracted rather than added to the static pressure. No reason not to use separate pitot and static pressures and combine them electronically. The TE probe was the solution back when vane type mechanical varios were the only option.

The best audio vario I've ever had, in terms of sound, was an old electronic "RICO VACS" from Redwood Instruments. It had electronic TE. The "ticks" it made, with both increasing frequency and pitch as lift got stronger, where easy to hear with low volume. Very weak lift sounded like an occasional tick. It was so easy to hear that I tried it in a powered plane and could hear it over the engine noise. Alas the 1970's electronics failed some time in the 2000's. I wish some current designs adopted its sound scheme, instead of annoying beeps.