Spatial Impulse Response Rendering (SIRR) is a recent technique for reproduction of room acoustics with a multichannel loudspeaker system. SIRR analyzes the direction of arrival and diffuseness of measured room responses within frequency bands. Based the analysis data, a multichannel response suitable for reproduction with any chosen surround loudspeaker setup is synthesized. When loaded to a convolving reverberator, the synthesized responses create a very natural perception of space corresponding to the measured room. In this paper, the SIRR method is described and listening test results are reviewed. The sound intensity based analysis is refined, and improvements for the synthesis of diffuse timefrequency components are discussed.

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Although voice has been used as an input modality in various user interfaces, there are no reports of using pitch of the user’s voice for real-time control of computer games. This paper explores pitch-based control for novel games for musical education. Mapping pitch to the position of a game character provides visual feedback that helps you to learn to control your voice and sing in tune. As demonstrated by two example games in this paper, the approach can be applied to both single and two-player games even with just one microphone.

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Pinna-Related Transfer Functions (PRTFs) reflect the modifications undergone by an acoustic signal as it interacts with the listener’s outer ear. These can be seen as the pinna contribution to the Head-Related Transfer Function (HRTF). This paper describes a database of PRTFs collected from measurements performed at the Department of Signal Processing and Acoustics, Aalto University. Median-plane PRTFs at 61 different elevation angles from 25 subjects are included. Such data collection falls into a broader project in which evidence of the correspondence between PRTF features and anthropometry is being investigated.

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Parametric spatial audio coding methods aim to represent efficiently spatial information of recordings with psychoacoustically relevant parameters. In this study, it is presented how these parameters can be manipulated in various ways to achieve a series of spatial audio effects that modify the spatial distribution of a captured or synthesised sound scene, or alter the relation of its diffuse and directional content. Furthermore, it is discussed how the same representation can be used for spatial synthesis of complex sound sources and scenes. Finally, it is argued that the parametric description provides an efficient and natural way for designing spatial effects.

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This paper details a software implementation of an acoustic camera, which utilises a spherical microphone array and a spherical camera. The software builds on the Cross Pattern Coherence (CroPaC) spatial filter, which has been shown to be effective in reverberant and noisy sound field conditions. It is based on determining the cross spectrum between two coincident beamformers. The technique is exploited in this work to capture and analyse sound scenes by estimating a probability-like parameter of sounds appearing at specific locations. Current techniques that utilise conventional beamformers perform poorly in reverberant and noisy conditions, due to the side-lobes of the beams used for the powermap. In this work we propose an additional algorithm to suppress side-lobes based on the product of multiple CroPaC beams. A Virtual Studio Technology (VST) plug-in has been developed for both the transformation of the time-domain microphone signals into the spherical harmonic domain and the main acoustic camera software; both of which can be downloaded from the companion web-page.

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Decomposing a sound-field into its individual components and respective parameters can represent a convenient first-step towards offering the user an intuitive means of controlling spatial audio effects and sound-field modification tools. The majority of such tools available today, however, are instead limited to linear combinations of signals or employ a basic single-source parametric model. Therefore, the purpose of this paper is to present a parametric framework, which seeks to overcome these limitations by first dividing the sound-field into its multi-source and ambient components based on estimated spatial parameters. It is then demonstrated that by manipulating the spatial parameters prior to reproducing the scene, a number of sound-field modification and spatial audio effects may be realised; including: directional warping, listener translation, sound source tracking, spatial editing workflows and spatial side-chaining. Many of the effects described have also been implemented as real-time audio plug-ins, in order to demonstrate how a user may interact with such tools in practice.

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