Juha Merimaa

Source localization in complex listening situations: Selection of binaural cues based on interaural coherence

In everyday complex listening situations, sound emanating from several different sources arrives at the ears of a listener both directly from the sources and as reflections from arbitrary directions. For localization of the active sources, the auditory system needs to determine the direction of each source, while ignoring the reflections and superposition effects of 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 in the 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 shown to imply the results of a number of published psychophysical studies related to source localization in the presence of distracters, as well as in precedence effect conditions.

Perceptually-based processing of directional room responses for multichannel loudspeaker reproduction

A novel method for processing directional room responses is proposed. Responses measured with a SoundField microphone or a comparable system are analyzed with an auditory resolution. From this data, loudspeaker responses for an arbitrary 2D or 3D surround sound reproduction system are synthesized. The processed responses yield a sharp and natural directional reproduction of the acoustics of a measured room. The methodology can also be applied to low bitrate audio coding of surround sound.