yes, you need to be more specific. audio covers underwater detection to ultrasound monitoring. the biggest problem is people don't want to pay you for the knowledge. they just see the stuff come out of a box from the orient at a low price without any thought as to what it took to get there. another ignorant comment is"It cost too much" with no thought as to preformance. but if it's free they will take it every time. that includes the knowledge that took you a lifetime to aquire, such as what the differences in dialectic mean is reproduction of sonic quality of reproduction. ieower amps and mic preamps.