API Spying

I am coding some software in c# and I require something that will tell my c# software when a certain function is called in a windows dll ([login to view URL]) ## Deliverables I would prefer the software to be in C# so I can integrate it directly with my current software, but if that is not possible then another language is fine (as long as it communications with my current software). It needs to raise an event in my c# software when some certain calls are made to [login to view URL] (specifically waveOutOpen and waveOutClose) from a specific exe ([login to view URL]) so as I can run a function in my software. Basically what I want, is when [login to view URL] (gps software) plays a sound - it will tell my software to turn its volume down until the sound is finished.