我們製作了一個音準練習程式：使用者輸入聲音後，經由音頻辨識方法求出其頻譜中最高振幅之頻率，以之為音高，再將其與目標音高相較，得到其誤差率及走音程度。此外還可發出對應的鋼琴及正弦波的聲音，方便使用者校音。文中說明音頻辨識的方法，一些關於音樂的基本知識，微軟公司的wave 檔格式，及此系統之應用。我們使用FFT 辨識頻率，且將針對此部分演算法做簡單的說明，並探討如何達到所需之頻率準確度，及如何以較高效率辨識。目前誤差率已可達到1Hz 以下，判斷時間也在秒之內。儘管國內外也有一些具備相似功能之音樂編曲軟體，但其功能十分繁複，使用者常需花費數週時間學習，且價格常高至數千元，非一般使用者所能負荷。而這個程式不但使用方便，功能簡單，容易上手，且不需任何費用。We have developed a singing-practicing program: after input the sound, we judge its pitch from the corresponding spectrum; then we compare it with the selected one, and output the deviation, so that the users can see if they had been out of tune. Also, we provide the sound of the piano and the sine wave sound of the chosen pitch, which can help users get the right pitch. This report will briefly introduce the method of pitch recognition, some basics of music, and Microsoft's wave file format. In addition, we explain the application of this program. We use FFT to transform a sound wave into the spectrum, which are briefly explained in the article, too. Also we’ll discuss how to improve the accuracy and efficiency of the transformation. So far the deviation is less than one Hertz, and the recognition takes less than one second. Though there have been some commercial software with similar functions, they are often complicated to use, and cost a lot. This is not affordable to most users. On the contrary, our program is not only convenient and easy to use, but also has a simple user interface. What’s more, it costs no money!
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