一般常見的數位音訊錄放設備，如果沒有品質較佳的播放器或耳機，或者是特別針對低音的播放裝置，僅利用一般的多媒體播放器或耳機要播放出低頻聲音是一件困難的事情。為了讓一般播放設備也能播出較低頻的聲音，相關文獻中提出以低頻頻寬擴展(又稱作虛擬音高或虛擬低音)的方法來改善此缺失，這個方法是利用心理聲學原理中的”遺失基頻”概念來模擬呈現低頻聲音。不過在產生虛擬音高的同時，通常會造成原本聲音有一定程度的失真，尤其當諧波產生器為非線性裝置時，人耳感受到不和諧的聲音特別明顯。
本研究針對此問題提出改進方法，研究成果顯示透由音高調變結合遮蔽效應產生虛擬音高的方法，能改善使用非線性裝置產生虛擬音高所導致聲音不和諧的感受；另一方面使用遮蔽效應能有效針對低頻能量較強的聲音做虛擬低音處理，能保有相同低音效果且降低因為產生虛擬音高所造成的失真。

It can hardly generate deep bass sound with small multimedia speakers or earphones in general digital audio playback devices. According to scientific and technical literatures, a low frequency bandwidth extension (also known as virtual pitch or virtual bass) method, which uses ‘missing fundamental ‘of the psychoacoustic concept to simulate the low frequency sound, is adopted for a general audio playback device to generate deep bass sound without an additional subwoofer or high equality speakers/ earphones. But when virtual pitches are generated, the original audio signal is accordingly distorted, and the unpleasant inharmonious sound is especially obvious for human ears while harmonic generator of non-linear type is used.
This research proposes improving the method to this problem, and the research result shows the method applying pitch scaling and masking effect to virtual pitch generation, which is capable of improving unpleasant feelings of inharmonious sound for human ears caused by using non-linear device to generate virtual pitch. Applying the masking effect can also effectively help moderate low frequency sounds with strong energy by virtual low frequency processing, and thus help remain the same base effect while reducing the distortion caused by virtual pitch generation.

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