利用共極串音消除器建立強健三度空間音效

Abstract

在現代多媒體系統中，有越來越多的虛擬實境應用。因此三度空間音效技術便越來越重要。我們將使用雙喇叭來產生三度空間音效。然而，主要的問題是串音(crosstalk)的干擾。我們將使用FIR和IIR兩種形式的串音消除器(crosstalk canceller)來解決這個問題。在這兩種內，我們都會提出反矩陣(matrix-inverse)或是直接最小平方錯誤(LSE)的方法。在反矩陣方法中，為了避免不穩定性，我們提出最小比例錯誤(ratio error)的方法。在直接LSE IIR設計中，為了避免非線性帶來設計上的困難，我們提出共極串音消除器結構。接下來我們將探討另一個問題，串音消除器的強健性。我們知道假如使用一組固定的串音濾波器，在頭可以移動的狀況下，接收到的信號將會和我們想要的信號差很多。因此，我們提出一個利用區域等化觀念的設計方法來降低頭移動造成的影響。最後，我們將用錯誤能量(EN)，串音壓制係數(CSF)和等化改善係數(EIF)來量化串音消除器的效能。

There are more and more virtual reality applications in the modern multimedia systems. Therefore, the 3D sound technique becomes more important. We will use a loudspeaker pair to generate the 3D sound. However, the most critical problem is the crosstalk disturbance. To overcome this problem, we investigate both FIR and IIR forms of crosstalk cancellers. In both forms, we propose matrix inverse and direct LSE methods to implement the filters. In matrix-inverse method, to avoid the un-stability, we propose to minimize the ratio error. In direct LSE IIR design, to avoid the nonlinearity, the common-pole structure is proposed. Then, we consider another problem, the robustness of the crosstalk canceller. We know that if the crosstalk canceller is fixed, and the received signals may be very different to the signals we want when the head moves. Therefore, we propose a method by using the region-equalized concept to reduce the effect of head movements. Finally, Error energy (EN), crosstalk suppression factor (CSF) and equalization improvement factor (EIF) are used to quantify the performance of crosstalk cancellers.