Hans-Joachim Maempel

Minimum BRIR grid resolution for dynamic binaural synthesis

Binaural synthesis of acoustical environments is based on binaural room impulse responses (BRIRs) measured with a certain grid of spherical coordinates separated by angles of typically between 1° and 15°. The resulting spatial resolution defines the size of the BRIR database as well as the duration of its measurement. Perceptual evaluations of datasets with a different spatial resolution using HRTFs (anechoic case) have been reported from. Most of these studies use the localization performance of listeners as a criterion; a more sensitive measurement for slight degradations in audio quality can be expected from a criterion‐free comparison of datasets with different angular grids. Thus, to determine the minimum grid resolution required for dynamic binaural synthesis a listening test was performed. Following an adaptive 3AFC procedure, the spatial resolution of a recorded BRIR dataset was gradually lowered from a maximum of 1°/1° resolution until audible artefacts were introduced. This was done for a sound ...

Auditory and Visual Contribution to Egocentric Distance and Room Size Perception

The perception of rooms involves various unimodal and multimodal aspects on different perceptual levels. Rather abstract yet self-evident aspects are the source distance and the room size. We investigated to what extent the perceived room size and egocentric source distance as supramodal aspects are based on the auditory and the visual modality, i.e. experimentally influenced by the acoustic and optical stimulus. The statistical determination of the respective contributions demands the mutually independent variation of optical and acoustical room properties, usually referred to as conflicting stimulus paradigm. Simulation data of four rooms were collected acoustically by acquiring binaural room impulse responses for different head orientations and optically by acquiring stereoscopic images of the rooms including the electroacoustic sound source. In the laboratory, respective acoustic scenes were played back applying dynamic binaural synthesis, whereas the optical scenes were presented by the use of a stereoscopic display. Test participants were asked to assess the source distance and the room size. Results show main effects of the modalities rather than an interaction effect. It was found that distance perception in rooms is predominantly based on the acoustic stimulus characteristics whereas room size perception predominantly relies on optical information. There is no evidence in favour of the proximity image effect hypothesis. Results do also not confirm an auditory or audio-visual underestimation of the source distance but show a general underestimation of room size and indicate an audio-visual asymmetry regarding the accuracy of room size perception. Maximum accuracy and cross-modal consistency of judgements were distinctively observed in low-absorbent rooms.

Audio-visual room perception: Cross-modal and interaction effects put to test

The perception of rooms involves different modalities, particularly hearing and sight. Fundamental issues such as the acoustical and optical shares in certain perceptual features have, however, not been experimentally addressed yet. We investigated to what extent the acoustical and optical properties of performance rooms influenced auditory and visual features. Specifically, cross-modal effects and interaction effects were a matter of particular interest. We also quantified the respective proportion of acoustical and optical information accounting for the perceptual features. The main preconditions for such an undertaking are the dissociation of the acoustical and optical components of the stimuli, the commensurability of these components, and rich cue conditions. We acquired binaural room impulse responses and panoramic stereoscopic images of six rooms in order to recreate these rooms virtually, and added recordings of both a music and a speech performance by applying dynamic binaural synthesis and chrom...

The influence of hearing and seeing on aesthetic judgments of performance spaces

The perception of rooms involves different modalities, particularly hearing and seeing. Fundamental questions of audio-visual room perception have, however, not been answered yet. We investigated to what extent aesthetic judgments on music and speech performances in different spaces are based on hearing, seeing, and their interaction. Meeting methodological criteria such as optoacoustic commensurability and optoacoustic dissociation, and applying a data-based, three-dimensional, high-resolution optoacoustic simulation providing nearly all perceptually relevant physical cues allowed for a valid proportionate quantification of these shares for the first time. BRIRs and panoramic stereoscopic images were acquired in six rooms. Recordings of both a music and a speech performance were put in the rooms by applying dynamic binaural synthesis and chroma-key compositing. The scenes were played back by the use of a linearized extraaural headset and a semi-panoramic stereoscopic projection system. Test participants ...