Capturing Spatial Room Information for Reproduction in XR Listening Environments
Abstract:
An expansion on previous work involving “holographic sound recording” (HSR), this research delves into how sound sources for directional ambience should be captured for reproduction in a 6-DOF listening environment. We propose and compare two systems of ambient capture for extended reality (XR) using studio-grade microphones and first-order soundfield microphones. Both systems are based on the Hamasaki-square ambience capture technique. The Twins-Hamasaki Array utilizes four Sennheiser MKH800 Twins while the Ambeo-Hamasaki Array uses four Sennheiser Ambeo microphones. In a preliminary musical recording and exploration of both techniques, the spatial capture from these arrays, along with additional holophonic spot systems, were reproduced using Steam Audio in Unity’s 3D engine. Preliminary analysis was conducted with expert listeners to examine these proposed systems using perceptual audio attributes.The systems were compared with each other as well as a virtual ambient space generated using Steam Audio as a reference point for auditory room reconstruction in XR. Initial analysis shows progress towards a methodology for capturing directional room reflections using Hamasaki-based arrays.
Multi-Directional Radiation Characteristic Recording Methods and Reproduction in an XR Environment
Abstract:
In this research, the idea of a “holographic sound recording” or HSR is explored to support applications where multi-directional radiation characteristics can be implemented to emulate a real sound source. We choose the term “holographic” due to its uncanny ability to create a realistic 3D sound source in a virtual acoustic space, similar to holographic visual experiences. Important factors such as acoustical points of interest, adequate number of microphones, pickup patterns and angles are explored, as well as capturing room acoustics and the benefits of player isolation. Specific recording techniques are introduced that can be used to create a holographic miking system called the Multi-timbral Hologram Array (MtH: pronounced “myth”) as a starting point for recordists who wish to create a holographic reproduction of a real sound source. The MtH Array can theoretically be fine-tuned and customized to help capture complex radiation characteristics of any acoustic instrument. An online companion links with extensive documentation in the medium of photos and playable files are included in the “Examples” section of the paper.
Ambisonic Spot Microphone Techniques for Ensemble Recording
Abstract:
Ambisonic microphones have long provided a flexible and eloquent method to capture surround sound with a compact microphone array. However, tetrahedral microphones are typically applied to free-field applications and often paired with traditional mono or stereo spot microphones when enhanced control over individual sound source panning, balancing and timbre is required. This paper investigates the use of tetrahedral microphones as a versatile spot microphone technique that can render both direct sound and supporting room impressions for multiple individual sound sources. Multiple recordings were made at New York University in the summer of 2021 to explore these techniques. A jazz quartet was recorded using three spot miking systems for comparison; an ambisonic-only system, a coincident paired ambisonic and omnidirectional spot system, and a more traditional multi-microphone system. In this paper, the techniques used will be explained and evaluated based on comparing Dolby ATMOS mixes rendered for each system.