One of the biggest mistakes people can make is to have their threshold set too high. Think of a target as being able to generate a specific level of sound. For giggles, lets say a dime at 5 inches can generate audio equivalent to a sound level of, say, 6. (that level could have been called a hippotomus, but I wanted to use numbers to make a point) And let's say you have your threshold set at a level of sound equivalent to a 10. For this example, the "6" generated by the dime is not enough "sound" to overcome the audio of the threshold which you have set at "10". But the inverse can be true as well. In other words, you can also set your threshold too low! Lets say you have your threshold set at silent search. Again, for giggles, let's say that represents a level of -7. In other words, it would take a target audio response of at least a 7 to make a sound. As you can see, this dime (with a level of "6") would not be enough to "break through" the threshold. The thing to remember is to set your threshold so you can just barely hear it. Set it so you can hear it well. And then back it off so it is just barely buzzing in the background. That way, any target will influence the threshold enough to "catch your atttention". Discriminated targets will blank it out. And accepted targets will cause it to increase.
Here is a post I made some time back, concerning the way a threshold can effect what you find..... http://www.findmall.com/read.php?55,811636,811646#msg-811646
I would guess that by lowering your threshold, you will be able to increase your sensitivity. Optimizing both settings should result in more finds. And keep in mind that Pattern One will reject some pretty good finds. http://www.findmall.com/read.php?55,569213,569213#msg-569213
JHMO HH Randy
I Gb'd threshold up high and sensitivity at 9/10 in pattern #1. 
