One: Sensor capable of sensing a heat source from a few feet away.
Two: A line or two of code to measure output of sensor that should vary with proximity to heat source.
Three: Result is a Sound Equipped Engine that "Sees" you at 5 feet increases from a low volume level and loudly passes you and reduces volume as it gains distance from you.
Problem: Where to put the sensor?
Problem: How to stop engine from roaring at max volume when in a club with many people?
Problem: Is there sensor robust enough and light enough to work well with a varying output that is readable by a volume control of QSI for example?
Or should we just leave the volume as they are according to our taste or peer pressure?
I'm not sure there are sensors (at a reasonable cost) that would be sensitive enough to respond that quickly.
Another, perhaps bigger problem, would be the inability of a sensor to differentiate between a distant heat source and the heat of the engine it's in.
Distance sensors, rather than heat, might work, but those I've seen are too bulky.
Mike Tennent