Pitch, Timbre, Surce Separation David Griesinger#39;s home page音高，音色，源分离戴维格和#主页39；.pptVIP

Conclusions for sound reproduction Localization in natural hearing takes place mostly at frequencies above 1000Hz, and has a precision of ~ 2 degrees in the horizontal plane. With care this precision can be reproduced over headphones from a binaural or amplitude panned recording. Commonly used pressure-gradient microphone techniques are not capable of capturing sound direction with this precision. The vey best they an do is about four degrees, and techniques that use cardioid microphones give at best about 8 degrees. Two channel loudspeaker reproduction suffers from frequency dependence for frequencies above 1000Hz, spreading apparent localization of a panned image over ~30 degrees. The brain must make a best guess for the perceived position of a source – and the frequency spread is sometimes audible. Multichannel reproduction in 5.1 improves the accuracy about a factor of two. The more channels used the more natural the frontal image becomes, as long as only two adjacent loudspeakers are active for any one source. First order Ambisonics with four speakers has all the problems of stereo and then some. With multiple speakers localization accuracy is slightly improved. * * * * * * * * Clarity, Distance, and Audience Attention We detect “near” versus “far” instantly on perceiving a sound “Near” sounds demand attention and sometimes immediate attention. “Far” sounds can usually be ignored Cinema and Drama directors demand that dialog be perceived as “Near” Drama theaters are small and acoustically dry Movie theaters are dry and use highly directional loudspeakers with linear phase response at vocal formant frequencies. High sonic clarity and low sonic distance requires that harmonics in the vocal formant range are reproduced with their original phase relationships. Unmodified by loudspeaker characteristics or reflections. The near/far perception is not commonly recognized when sound is reproduced, either in live performance or in recordings. Example of Clarity for Spee