Swamped

It occurs to you that if you had the parts, you could make a second eavesdropper and modify it to only pick up your voice. Then you could send it to your host and use it to bargain more directly, using the first to hear his responses.

Unfortunately, at this point he'd get suspicious if you tried to ask for more parts. Still, you can think of one thing you have a chance at getting, as long as you're acting cooperative.

So you send a note back.

Could you at least send me a functioning voice box at the correct size, so I can see if there are any incompatibilities I need to resolve?

A few minutes later, you get a response.

I doubt there will be any problems, but I will permit it. Here is the device. Be careful with it, please.

Well. You can buy some time, and maybe pull a few more tricks, by pretending you need to make some adjustments.

You consider trying to set up your own echolocation device, to give you some sense of how the outside hall is laid out and if it's worth making a run for it. But you're not a bat. You wouldn't be able to grasp the shape from echoes alone. You'd need some way to display the information so that you can understand it, and you're not sure just how you'd do that even if you had the right tools at hand to make it.

And he's not going to give you more tools... unless you tell him you couldn't get it to work at the smaller scale and you need something to adjust it. But even then, he's probably going to be wary of what he gives you.

Well. At this point, it looks like you'll either need to think of a good way to use what you've already got at hand, or think of a tool you can ask for that won't raise his suspicions.