Excellent idea! Do you need to calibrate it to be able to repeat it, and does that calibration change if you are at a different altitude and in different condi

Excellent idea! Do you need to calibrate it to be able to repeat it, and does that calibration change if you are at a different altitude and in different conditions, such as humidity? Does merely changing altitude (or ambient pressure) change voice enough to be considered different by a recognition or synthesizing system?