Hello there audio pro and mavin people! I have this primitive hobby project, where an Arduino micro-controller board communicates with a Smartphone, via the phone audio jack. The phone plays these Audio files and the Arduino samples the voltage on the audio line, in order to discern between high voltage, low voltage and no voltage. It's a simple project and it already works OK without any amplification and that is how i want it to stay, for this project (without amplification). But i have a suspicion that it could work even better, if i had a bit more knowledge about the types of sounds, that produce various levels of voltage on an audio line. What i am using now is a sound of a siren, that i recorded with such a gain, that it is full of distortion. i think distortion is good for my case, since it seems to be decoded by the Arduino, as a high voltage signal most of the time. But when i installed a primitive sound editor software on my computer and set the graphic view of the sound file in a certain way, i saw that actually only small portions of that sound file, raises the sound magnitude to the maximum possible gain. My conclusion was that it must be surly possible to create a sound file, that produces even a higher constant voltage on the audio line. The sound file runs for 5-10 seconds. So my question is what kind of sound sample would produce the highest voltage on an audio line? Thanks.