The reason for this article and the application accompanying it is an idea of an automated pronunciation test I've been flirting with for a few months now. Due to the difficulties found and some frustration, I thought giving it up three or four times, but in the end the inner "never give up" voice had the upper hand and eventually won. Fortunately, I ended up with a solution, which I admit is not perfect and one that got far away from my initial "development track". But this is how it often goes when you find difficulties, you embrace whatever tools that work for you.

The first problem was to find code or component to generate the so-called "pitch contour" for the analysis. The pitch contour is the melody that follows human voice, more technically the fluctuation in frequency that accompanies voice. I tried hard to find that magical "open source .Net code" which included the pitch contour calculation, searching the internet, but with no success. I found some open source solutions, but sadly they're not written in .Net code (mostly in C++/Python). Sadly, too, I'm not expert in C++ or Python, plus the code is too large to be ported. Also, I'm not expert in the mathematical algorithms (such as Fast Fourier Transform) which are needed for creating a new library from scratch. So I ended up with a "collaboration" between server-side c# program and a console python application. Not particularly pretty, since I initally planned an all-client-side, managed code, but it works and that's what matters. I hope some code hero in the .Net community come up with a more elegant solution fot that.

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The second problem is trying to compare the user voice against the predefined exercise voice and providing a score. How can I compare both pitch contours? I had no tools for such task, so I had to come up with a new one. It took me many hours of work and still it's not perfect, but the only one I had so far. Like in the previous problem, a code hero would save the day here.

I guess you came to this post by searching similar kind of issues in any of the search engine and hope that this resolved your problem. If you find this tips useful, just drop a line below and share the link to others and who knows they might find it useful too. 


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