I'm going to write an application in Silverlight that consists of 2 threads, one that plays sound and another that records sound. And whatever is recorded will be what was played plus some ambient noise.
The problem is that Silverlight adds a delay to the sound to be played, and because I don't know how much is this delay, I would not know precisely what was played when something is recorded.
Do you know where I can find more information about this delay (how much is it, is it constant, will it change if I restart my application or computer, will it be the same in different computers, ...), or how could I measure it with an accuracy of 1 ms?
To measure the delay you can play some form of generated sound (like sin wave with increasing amplitudes), capture it and match input and output signals.
The delay itself is a complicated matter especially when dealing with low latencies. There are a lot of things involved in building delay including SL itself, audio stack, OS and audio hardware. Some additional info is here.