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I am new to sphinx4 and speech recognition thing. I am creating a speech application by using sphinx4. The issue is noise, which results in recognition by program even without speech input by user ie it is converting speech to text even when there is no speech input by user, thus affecting accuracy.

Main issue is how to implement noise reduction. This is because the system detects input even when I dont speak anything into the microphone. So I guess its because of noise.

I checked online for noise reduction but there is hardly clear information about the same. Though there is some information over internet about file named Denoise.java which comes with sphinx4. But it is not there in sphinx4-1.06.

Another file is WienerFilter.java, wienerfilter is type of filter used for noisy signals. But no instructions for using or implementing that file.

I have already added few more words to hello.gram which is the grammar file for the program. The phonetic representation of those extra words, generated by Imtool, has been added to the dictionary.

I am using eclipse and sphinx4-1.0beta6

Though there is one question on stack overflow on "HOW TO ACITIVATE NOISE CANCELLATION " IN SPHINX4 but that has not been answered yet

MANU
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  • Though there is one question on stackoverflow on "HOW TO ACITIVATE NOISE CANCELLATION " IN SPHINX4 but that has not been answered yet. – MANU Mar 15 '15 at 09:56
  • I can't understand why the question is being voted down... If some more information is required then leave a comment instead of voting down the question – MANU Mar 15 '15 at 13:41
  • You are trying to ask too many questions at once, so the question is too broad. Question about noise is one, question about accuracy is another question, question about detection of extra speech is a third question. Try to make your question more specific. – Nikolay Shmyrev Mar 15 '15 at 13:53
  • @Nikolay Shmyrev thanx for your comment.......now I have edited my question a lil........and thing is that noise and accuracy are related in some sense that is noise will definitely affect speech recognition accuracy thats why I mentioned both – MANU Mar 15 '15 at 14:42

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Static noise cancellation with spectral subtraction is enabled by default in latest version sphinx4-5prealpha. You do not need to do anything special, just use the latest version.

Follow the tutorial:

http://cmusphinx.sourceforge.net/wiki/tutorialsphinx4

Extra speech is ignored in latest version if you are using grammar decoding, not large vocabulary decoding with language model. If you use grammar decoding it should ignore all the words in the grammar. For words not in the grammar it should return a special word <unk>.

Accuracy debugging is a complex process and requires a test recording to reproduce accuracy problems. Without test recording it is hard to suggest you how to improve accuracy. Beside test recording you need to provide models you use in decoding and other information to reproduce your results.

Nikolay Shmyrev
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