This might not be the answer you are looking for but when I encounter this kind of problem in my code I usually (1) Add debugging code to output information. I'm not sure if you are using AudioLine but if you are you can add print statements around the code where the audio line is opened, started, and data is written to it. This will confirm whether the audio line is being used as expected. (2) If you have a method generating white noise (e.g., an array of random values or an audio buffer), print out the first few samples of the array to see if they are generated as expected.