Berauti Spectral Subtraction dengan Gaussian Window untuk Peningkatan Akurasi Pengenalan Ucapan Berderau

The accuracy of speech recognition system decreases when used on a noisy speech. Therefore, the speech recognition system needs to be supported by a speech enhancement method. This study proposes Berauti spectral subtraction method that uses gaussian window and minimum statistics noise estimation in order to improve the quality of noisy speech hence increase the accuracy of noisy speech recognition. Speech recognition system is built using the Hidden Markov Model Toolkit (HTK). This study applied three types of noise, five SNR levels, six oversubtraction values and four sidelobe gaussian window attenuation values with 1500 speech signals. Improvement of speech recognition accuracy using Gaussian window is compared with Hamming window. The results of the study shows that sidelobe and oversubtraction attenuation values affects recognition accuracy. The average speech recognition accuracy using gaussian window  improve about 36.4%  which is obtained at oversubtraction  4.75 and  sidelobe attenuation = 1.5. Whereas, application of hamming window improves the accuracy about 18,7 % which is obtained at oversubtraction 2.5. Spectral subtraction using gaussian window or hamming window is able to improve the speech recognition accuracy, but gaussian window  is better than hamming window. Keywords : Berauti spectral subtraction, gaussian window,  speech recognition  AbstrakAkurasi sistem pengenalan ucapan menurun ketika digunakan pada ucapan berderau. Oleh karena itu, sistem pengenalan ucapan perlu didukung dengan metoda perbaikan sinyal ucapan. Pada penelitian ini diusulkan metoda Berauti spectral subtraction yang menerapkan gaussian window dan estimasi derau minimum statistik untuk memperbaiki kualitas sinyal berderau sehingga dapat meningkatkan akurasi pengenalan ucapan berderau. Sistem pengenalan ucapan dibangun menggunakan Hidden Markov Model ToolKit (HTK). Pada penelitian ini divariasikan tiga jenis derau, lima level SNR, enam nilai oversubtraction dan empat nilai redaman sidelobe gaussian window dengan 1500 sinyal ucapan. Peningkatan akurasi pengenalan ucapan yang menggunakan gaussian window dibandingkan dengan hamming window. Hasil penelitian ini menunjukan pemilihan nilai redaman sidelobe dan oversubtraction mempengaruhi akurasi pengenalan. Rata-rata peningkatan akurasi pengenalan ucapan sebesar 36,4 % diperoleh pada nilai oversubtraction 4.75 dan  redaman sidelobe 1.5. Penggunaan hamming window memiliki rata-rata peningkatan akurasi pengenalan sebesar 18,7 % pada nilai oversubtraction 2.5. Metoda spectral subtraction yang menggunakan gaussian window  atau  hamming window, keduanya mampu menaikan akurasi pengenalan ucapan, akan tetapi gaussian window memiliki hasil yang lebih baik dibanding hamming window Kata Kunci : Berauti spectral subtraction, gaussian window, pengenalan ucapa

Berauti Spectral Subtraction dengan Gaussian Window untuk Peningkatan Akurasi Pengenalan Ucapan Berderau

The accuracy of speech recognition system decreases when used on a noisy speech. Therefore, the speech recognition system needs to be supported by a speech enhancement method. This study proposes Berauti spectral subtraction method that uses gaussian window and minimum statistics noise estimation in order to improve the quality of noisy speech hence increase the accuracy of noisy speech recognition. Speech recognition system is built using the Hidden Markov Model Toolkit (HTK). This study applied three types of noise, five SNR levels, six oversubtraction values and four sidelobe gaussian window attenuation values with 1500 speech signals. Improvement of speech recognition accuracy using Gaussian window is compared with Hamming window. The results of the study shows that sidelobe and oversubtraction attenuation values affects recognition accuracy. The average speech recognition accuracy using gaussian window improve about 36.4% which is obtained at oversubtraction 4.75 and sidelobe attenuation = 1.5. Whereas, application of hamming window improves the accuracy about 18,7 % which is obtained at oversubtraction 2.5. Spectral subtraction using gaussian window or hamming window is able to improve the speech recognition accuracy, but gaussian window is better than hamming window