Interactive real-time auralization of airborne sound insulation in buildings

Sound insulation auralization can be used as valuable tool to study the perceptual aspects of sound transmission in built environments for assessment of noise effects on people. It may help to further develop guidelines for building constructions. One advanced goal of real-time sound insulation auralization is to appropriately reproduce the condition of noise effects on the human perception and cognitive performance in dynamic and interactive situations. These effects depend on the kind of noise signal (i.e. speech, music, traffic noise, etc.) and on the context. This paper introduces a sound insulation auralization model. The sound insulation filters are constructed for virtual buildings with respect to complex sound propagation effects for indoor and outdoor sound sources. The approach considers the source room sound field with direct and diffuse components along with source directivity and position. The transfer functions are subdivided into patches from the source room to the receiver room, which also covers composite building elements, thus providing more detail to the actual building situations. Furthermore, the receiving room acoustics includes the reverberation of the room based on its mean free path, absorption and binaural transfer functions between its radiating walls elements and the listener. This more exact approach of sound insulation model agrees reasonably well with the ISO standard (i.e. diffuse field theory) under standard settings. It is also shown that the sound field significantly influences the transmitted energies via building elements depending on the directivity and position of the source. The proposed method is validated as a general scheme and includes more details for real-time auralization in specific situations especially in the cases where the simplified diffuse sound field approach fails. It is capable to be used in interactive Virtual Reality (VR) systems, which opens new opportunities for psychoacoustics research in noise effects on human.

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Efficient binaural rendering of spherical microphone array data by linear filtering

EURASIP Journal on Audio Speech and Music Processing ◽

10.1186/s13636-021-00224-5 ◽

2021 ◽

Vol 2021 (1) ◽

Author(s):

Johannes M. Arend ◽

Tim Lübeck ◽

Christoph Pörschmann

Keyword(s):

Real Time ◽

Transfer Functions ◽

Finite Impulse Response ◽

Microphone Array ◽

Sound Field ◽

Limited Range ◽

Time Signal ◽

Head Orientation ◽

Linear Filtering ◽

Spatial Sound

AbstractHigh-quality rendering of spatial sound fields in real-time is becoming increasingly important with the steadily growing interest in virtual and augmented reality technologies. Typically, a spherical microphone array (SMA) is used to capture a spatial sound field. The captured sound field can be reproduced over headphones in real-time using binaural rendering, virtually placing a single listener in the sound field. Common methods for binaural rendering first spatially encode the sound field by transforming it to the spherical harmonics domain and then decode the sound field binaurally by combining it with head-related transfer functions (HRTFs). However, these rendering methods are computationally demanding, especially for high-order SMAs, and require implementing quite sophisticated real-time signal processing. This paper presents a computationally more efficient method for real-time binaural rendering of SMA signals by linear filtering. The proposed method allows representing any common rendering chain as a set of precomputed finite impulse response filters, which are then applied to the SMA signals in real-time using fast convolution to produce the binaural signals. Results of the technical evaluation show that the presented approach is equivalent to conventional rendering methods while being computationally less demanding and easier to implement using any real-time convolution system. However, the lower computational complexity goes along with lower flexibility. On the one hand, encoding and decoding are no longer decoupled, and on the other hand, sound field transformations in the SH domain can no longer be performed. Consequently, in the proposed method, a filter set must be precomputed and stored for each possible head orientation of the listener, leading to higher memory requirements than the conventional methods. As such, the approach is particularly well suited for efficient real-time binaural rendering of SMA signals in a fixed setup where usually a limited range of head orientations is sufficient, such as live concert streaming or VR teleconferencing.

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