How can I make Speakable Items respond just to a keyword?

I’m relatively inexperienced at AppleScript, but I’m trying to accomplish something that is likely quite simple. Any help would be greatly appreciated.

In the context in which I’m using speakable items, I’ve found that I can’t omit the use of a keyword, nor is it practical for me to use a physical (keyboard) key, hence, I’m using a keyword, but with a listen interval of 15 seconds. First, is there any way to add another interval level, say, 5 seconds? Sometimes, 15 seconds is a bit long, but requiring the keyword before every command is clumsy in the context in which I’m using it. For example, if I script the dialing of a phone number via a softphone, the other party may answer (over speakerphone) before the 15-second interval is over, and the computer may start “responding” to what it thinks are commands for something else. Lowering the interval to 5 seconds would greatly reduce the likelihood of this - the listening interval would be over before the other party could answer, but 5 seconds is still long enough to sequence commands when that is what is intended.

Second, is it possible to configure Speakable Items to acknowledge the keyword itself? Here’s the current scenario…The user first says the keyword “computer”, which tells the Speech Recognition engine to listen for actual commands for the 15 second interval I’ve set in the preferences. The computer is now listening for an actual command, but if the command isn’t recognized (in which case nothing happens), the user doesn’t know right away if it was because their command was misstated, or if the keyword itself wasn’t recognized (at least without looking at the speakable items “microphone window”). The user might again say “computer” and then the command, or suspect that it was only the command that was not interpreted, and try saying the command once or twice, to no avail, and then “computer” and the command again. If the computer could respond to the keyword (for example, with “Yes, master?”), then the user would know that the keyword was recognized, and any failure to execute a command is therefore only due to the command being misinterpreted or not recognized (or the interval lapsing) - there’s no doubt that they keyword was recognized, though.

Ideas? Thanks very much!