Real-time dynamic image-source implementation for auralisation

This paper describes a software package for auralisation in inter- active virtual reality environments. Its purpose is to reproduce, in real time, the 3D soundfield within a virtual room where listener and sound sources can be moved freely. Output sound is presented binaurally using headphones. Auralisation is based on geometric acoustic models combined with head-related transfer functions (HRTFs): the direct sound and reflections from each source are computed dynamically by the image-source method. Directional cues are obtained by filtering these incoming sounds by the HRTFs corresponding to their propagation directions relative to the listener, computed on the basis of the information provided by a head-tracking device. Two interactive real-time applications were developed to demonstrate the operation of this software package. Both provide a visual representation of listener (position and head orientation) and sources (including image sources). One focusses on the auralisation-visualisation synchrony and the other on the dynamic calculation of reflection paths. Computational performance results of the auralisation system are presented

Head-tracked auralisations for a dynamic audio experience in virtual reality sceneries

This paper aims to take advantage of the new cutting-edge virtual reality technologies – such as head-mounted displays for virtual reality and ambisonics – in order to recreate 3D immersive environments; both aural and visual. The work presented here is believed to encourage investigations into buildings yet to be, or those lost to civilisation. Through a combination of acoustic computer modelling, network protocol, game design and signal processing, this paper proposes a method for bridging acoustic simulations and interactive technologies, i.e. fostering a dynamic acoustic experience for virtual scenes via VR-oriented auralisation

Building Information Modeling (BIM) 02 Further exploration in Architecture, Engineering and Construction: Civil and Architectural Engineering

The technical report is a part of a research assignment carried out by students in the 5 ETCS course “Integrated Engineering Project”, during the 2nd semester of the master degree in Civil and Architectural Engineering, Department of Engineering, Aarhus University. This includes seven papers describing BIM for thematic subjects in Architectural Engineering and Construction Management

VR-based Soundscape Evaluation: Auralising the Sound from Audio Rendering, Reflection Modelling to Source Synthesis in the Acoustic Environment

Soundscape has been growing as a research field associated with acoustics, urban planning, environmental psychology and other disciplines since it was first introduced in the 1960s. To assess soundscapes, subjective validation is frequently integrated with soundscape reproduction. However, the existing soundscape standards do not give clear reproduction specifications to recreate a virtual sound environment. Selecting appropriate audio rendering methods, simulating sound propagation, and synthesising non-point sound sources remain major challenges for researchers. This thesis therefore attempts to give alternative or simplified strategies to reproduce a virtual sound environment by suggesting binaural or monaural audio renderings, reflection modelling during sound propagation, and less synthesis points of non-point sources. To solve these unclear issues, a systematic review of original studies first examines the ecological validity of immersive virtual reality in soundscape evaluation. Through recording and reproducing audio-visual stimuli of sound environments, participants give their subjective responses according to the structured questionnaires. Thus, different audio rendering, reflection modelling, and source synthesis methods are validated by subjective evaluation. The results of this thesis reveal that a rational setup of VR techniques and evaluation methods will be a solid foundation for soundscape evaluation with reliable ecological validity. For soundscape audio rendering, the binaural rendering still dominates the soundscape evaluation compared with the monaural. For sound propagation with consideration of different reflection conditions, fewer orders can be employed during sound reflection to assess different kinds of sounds in outdoor sound environments through VR experiences. The VR experience combining both HMDs and Ambisonics will significantly strengthen our immersion at low orders. For non-point source synthesis, especially line sources, when adequate synthesis points reach the threshold of the minimum audible angle, human ears cannot distinguish the location of the synthesised sound sources in the horizontal plane, thus increasing immersion significantly. These minimum specifications and simplifications refine the understanding of soundscape reproduction, and the findings will be beneficial for researchers and engineers in determining appropriate audio rendering, sound propagation modelling, and non-point source synthesis strategies

Acoustic heritage and audio creativity: the creative application of sound in the representation, understanding and experience of past environments

Acoustic Heritage is one aspect of archaeoacoustics, and refers more specifically to the quantifiable acoustic properties of buildings, sites and landscapes from our architectural and archaeological past, forming an important aspect of our intangible cultural heritage. Auralisation, the audio equivalent of 3D visualization, enables these acoustic properties, captured via the process of measurement and survey, or computer based modelling, to form the basis of an audio reconstruction and presentation of the studied space. This paper examines the application of auralisation and audio creativity as a means to explore our acoustic heritage, thereby diversifying and enhancing the toolset available to the digital heritage or humanities researcher. The Open Acoustic Impulse Response (OpenAIR) library is an online repository for acoustic impulse response and auralisation data, with a significant part having been gathered from a broad range of heritage sites. The methodology used to gather this acoustic data is discussed, together with the processes used in generating and calibrating a comparable computer model, and how the data generated might be analysed and presented. The creative use of this acoustic data is also considered, in the context of music production, mixed media artwork and audio for gaming. More specifically to digital heritage is how these data can be used to create new experiences of past environments, as information, interpretation, guide or artwork and ultimately help to articulate new research questions and explorations of our acoustic heritage

Room acoustics and virtual reality: An implementation of auralisation and 360 degree image techniques to create virtual representations of spaces

There has been a huge increase in enthusiasm for virtual reality in recent years. Spatial audio is of significant importance when creating virtual reality content if the experience is to be perceptually congruent. This project aims to intersect the worlds of virtual acoustic auralisation and virtual reality, creating a novel method of demonstrating room acoustic environments with maximal audio visual impact in a user friendly fashion. An open source library of 3D impulse responses together with 360° image/video capture using a variety of techniques will be created in different spaces (and positions within). Various spaces will be measured and analysed including classrooms, music venues, buildings of historical interest and theatres. As well as impulse response (IR) measurements, 360° images will be recorded using photospheres, captured on android smart phones [1] and the Ricoh theta S [2]. Future applications for these impulse responses will be the development of a virtual mixing tool, where the user will be able to experience mixing live performances within an auralised virtual environment, a method of allowing audiences to view and hear auralisations of different seating positions within a space for ticketing and marketing purposes, and the possibility of a real time auralised virtual concert.N/

3D environmental sound field auralisation - feasibility, development and business case (redacted version)

Environmental noise auralisation has the potential to improve communication between acoustic consultants and clients, project stakeholders and the community. This audible demonstration of the future sound environment enables non-technical stakeholders to experience proposed changes to the project site and surroundings realistically. Through the development of an environmental noise auralisation tool, context analysis, stakeholder interviews, and a business case, this report establishes that using environmental noise auralisation for community consultation is possible. For Marshall Day Acoustics’ Christchurch office, there are potentially XXX projects per year that would use environmental noise auralisation. Auralisations are most accurate when presented in a controlled environment, so investment in a Listening Room would be necessary to provide this service to clients alongside further development of the prototype tool. Cash flow calculations for this investment incorporating XXX projects per year with a fixed fee of $XXX, estimated a 20-year net present value of$ XXX and a worst-case net present value of $XXX. The project has an estimated present value index of$ XXX, representing a $ XXX return per dollar invested. Considering this financial return and the project’s alignment with MDA’s strategy and capabilities, the development of the environmental noise auralisation tool and the Listening Room is recommended

Auralisation of Traffic Flow using Procedural Audio Methods

This thesis investigates approaches for the auralisation of traffic noise in an outdoor environment. A novel auralisation framework for multiple vehicle pass-bys using procedural audio methods is proposed. This includes sound source modelling of single vehicle pass-bys and traffic flow, sound propagation modelling, and HRTF processing for spatial audio reproduction. Compared to prior auralisation studies in which sound source recordings have been used, no pre-recorded sounds are used with a procedural audio approach. Instead, synthetic sounds created by programmatic rules form the basis of the auralisation framework proposed in this thesis. Such an auralisation based on procedural audio gives greater freedom and range in the implementation and integration of vehicle pass-by sounds, with the advantage of high flexibility and variable computational cost for the algorithms defining the properties of any given audio objects. However, such synthetic sounds might not be perceived as being plausible when compared to their recorded counterparts, especially for the case of traffic noise where it is difficult to imitate the intrinsic rich and varied sound source content by artificial means. Therefore, two subjective listening tests are implemented to evaluate the plausibility of the proposed auralisation framework by comparing procedurally generated vehicle sounds to their counterparts created using a recording-based granular synthesis method. Engine sounds, engine plus tyre sounds, and single vehicle pass-by sounds, all generated using a procedural audio approach, are compared with their counterparts created using a granular synthesis method, and evaluated in an ABX listening test. It is found that a similar level of plausibility is achieved by using either method for the auralisation of single vehicle pass-bys. Based on this validation, the plausibility of multiple vehicle pass-by sounds with engines synthesised using a procedural, a mix of procedural and granular, and granular approaches is evaluated in a MUSHRA test under various traffic flow conditions regarding different vehicle types, speeds, driving directions, and flow rates. It is found that a similar level of plausibility is achieved by using either method under most traffic flow conditions. These results verify that the auralisation of traffic flow using procedural audio methods is comparable to recording-based approaches when considering the plausibility of the results obtained. Such an approach provides a solution for implementing the auralisation of environmental sounds that is both flexible and plausible, which is useful for communicating and demonstrating the important changes in our soundscape to the wider population, leading to a more holistic understanding of environmental sound