I agree with @tenkan. When I worked with Signia’s version, I would often cycle through the different types of sound (white, pink, brownian, etc.) until the patient said, “Wow!” I wasn’t really given much training on this (“training” being a 4-letter word in my previous company), so I had to play around with it. I’ve seen the masking have instant, dramatic results, and I’ve seen it have zero results. One thing I did learn is that the masking should be set so that it is barely audible. In the beginning, you’re “supposed” to hear both the tinnitus and the masking at the same time. Your brain is supposed to start ignoring the tinnitus. From what I understand, it’s more retraining your brain than instant result.
That being said, I have seen it have an instant effect.