The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Analysis, Synthesis, and Perception of Spatial Sound – Binaural Localization Modeling and Multichannel Loudspeaker Reproduction
Juha Merimaa
Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S5 at Helsinki University of Technology (Espoo, Finland) on the 11th of August, 2006, at 12 o'clock noon.
Dissertation in PDF format (ISBN 951-22-8291-7) [5145 KB]
Dissertation is also available in print (ISBN 951-22-8290-9)
Abstract
In everyday audio environments, sound from several sources arrives at a listening position both directly from the sources and as reflections from the acoustical environment. This thesis deals, within some limitations, with analysis of the resulting spatial sound field, reproduction of perceptually relevant features of the sound as measured in a chosen listening position, as well as with modeling of the related auditory localization.
For the localization, the auditory system needs to independently determine the direction of each source, while ignoring the reflections and superposition effects of any possible concurrently arriving sound. A modeling mechanism with these desired properties is proposed. Interaural time difference (ITD) and interaural level difference (ILD) cues are only considered at time instants when only the direct sound of a single source has non-negligible energy within a critical band and, thus, when the evoked ITD and ILD represent the direction of that source. It is shown how to identify such time instants as a function of the interaural coherence (IC). The source directions suggested by the selected ITD and ILD cues are also shown to imply the results of a number of published psychophysical studies.
Although the room reflections are usually suppressed in auditory localization, they contribute to the perception of the acoustical environment. The reviewed physical analysis techniques and psychoacoustical knowledge on spatial hearing are applied in development of the Spatial Impulse Response Rendering (SIRR) method. SIRR aims at recreating ITD, ILD, IC, and monaural localization cues by using a perceptually motivated analysis-synthesis method. The method is described in the context of multichannel loudspeaker reproduction of room responses with convolving reverberators. The analyzed quantities consist of the time- and frequency-dependent direction of arrival and diffuseness of sound. Based on the analysis data and a recorded omnidirectional signal, multichannel responses suitable for reproduction with any chosen surround loudspeaker setup are synthesized. In formal listening tests, it is shown that SIRR creates a more natural spatial impression than can be achieved with conventional techniques.
Keywords: auditory localization, binaural models, precedence effect, multichannel reproduction, room responses
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© 2006 Helsinki University of Technology
Last update 2011-05-26