2. TIME-SHIFTED PRINCIPAL COMPONENT ANALYSIS BASED CUE EXTRACTION FOR STEREO AUDIO SIGNALS Jianjun HE, Ee-Leng Tan, Woon-Seng Gan Digital Signal Processing Lab, School of EEE, Nanyang Technological University, Singapore 15 th May 2013 Email: JHE007@e.ntu.edu.sg

3. TIME-SHIFTED PRINCIPAL COMPONENT ANALYSIS BASED CUE EXTRACTION FOR STEREO AUDIO SIGNALS Outline 2 1. Introduction 2. Stereo signal model 3. Cue extraction using PCA 4. Cue extraction using Shifted PCA 5. Experimental results 6. Conclusions

4. Introduction 3 Cue — Where the sound comes from? Ambience — Where are you?

5. Cues highly correlated Ambience uncorrelated Cue ambience uncorrelated Ambience power balanced Stereo Signal Model 4 Signal = Cue + Ambience Assumptions

6. Stereo Signal Model 5 k 1 Center Right Left 1/10 10

7. Cue extraction using Principal component analysis (PCA) 6 M. Goodwin and J. M. Jot, “Primary-ambient signal decomposition and vector-based localization for spatial audio coding and enhancement,” IEEE Int. Conf. on Acoustics, Speech, and Signal Processing, April 2007.

8. PCA based cue extraction 7 Problems remains with Performance of PCA based cue extraction with varying (k=3). (a) ECR; (b)-(c) extraction similarity; (d) ILD error Practically, ITD ≡ 0 Error Localization parameters:  Inter-channel time difference (ITD)  Inter-channel level difference (ILD)

9. PCA based cue extraction 8 Problems remains with So what can we do?

10. PCA based cue extraction 9 Shifted PCA Decomposition Cues Stereo input signal Time Shifting ITD Estimation Output Mapping

11. Performance comparison between PCA and SPCA 10 Synthesized signals: Cue: speech amplitude panned by 3 and shifted by 40 time units Ambience: uncorrelated white Gaussian noise CER: [0.5, 1] Synthesized signals: Cue: speech amplitude panned by 3 and shifted by 40 time units Ambience: uncorrelated white Gaussian noise CER: [0.5, 1] SPCA PCA

12. Conclusions 11 In practice, cues in stereo signal can be time shifted and amplitude panned. ITD Cue correlation ILD Error Similarity Retained Increased Corrected Reduced Increased Lost Dropped Exaggerated Higher Lower SPCA PCA SPCA PCA outperforms in cue extraction with time shifting operation.

13. Email: JHE007@e.ntu.edu.sg TIME-SHIFTED PRINCIPAL COMPONENT ANALYSIS BASED CUE EXTRACTION FOR STEREO AUDIO SIGNALS

14. PCA based cue extraction 13 Problems remains with Performance of PCA based cue extraction with varying (a) Error to cue power ratio; (b)-(c) extraction similarity; (d) ILD error