A Spherical Microphone And Compact Loudspeaker Array Measurement Database For The Study Of Concert Hall Preference

A Spherical Microphone and Compact Loudspeaker Array Measurement Database for the Study of Concert Hall Preference

Concert hall acoustics is an inherently conflicted, perceptual art form that meets the practical, engineering-based design process. What began as a trade learned on the job from experts has gradually evolved to an engineering-rooted discipline through computer simulations, impulse response measurement techniques, and auralization. Despite these advances, engineering design practices and processes must be fundamentally related to human perception that has driven the field for many centuries.The goal of this current work was to study concert hall perception using spherical array processing techniques in a wide variety of real concert halls. For the study, the concert hall orchestral research database, or CHORDatabase, was generated, consisting of spherical microphone and compact spherical loudspeaker array (CSLA) room impulse response (RIR) measurements in 21 concert halls. The concert halls in the database include a wide variety in shape, size, reverberance, and geography, including 15 North American and 6 European halls.RIR measurements were made using a 32-channel spherical microphone array and a three-part omnidirectional sound source, which enabled high-resolution spatial beamforming analysis and standard room acoustic metric calculations. As well, the microphone array enables spatially accurate auralizations using higher-order Ambisonics over a 30-loudspeaker auralization array. Finally, a 20-channel CSLA was built to flexibly reconstruct the frequency-dependent radiation patterns of different orchestral instruments. Using this source, repeatable and realistic full-orchestral auralizations were generated for each concert hall. A subjective study investigated which factors were most important regarding concert hall perception and preference. A factor analysis revealed three to four factors of importance, relating to clarity, strength / spaciousness, and brilliance. Average preference best correlated with the perception of proximity, and for individuals, preference varied substantially, showing correlations with both the clarity and strength / spaciousness factors. Finally, spherical array beamforming analysis revealed time and spatial RIR regions that strongly correlated with envelopment, proximity, source width, and average preference. All of these perceptual attributes either lack a standardized metric or showed little correlation with the currently proposed metric to predict their perception in ISO 3382. Promising outlook is seen for developing new, perceptually-informed metrics using spherical array processing techniques. This project was supported through the National Science Foundation, Award #1302741.

Ambisonics

This open access book provides a concise explanation of the fundamentals and background of the surround sound recording and playback technology Ambisonics. It equips readers with the psychoacoustical, signal processing, acoustical, and mathematical knowledge needed to understand the inner workings of modern processing utilities, special equipment for recording, manipulation, and reproduction in the higher-order Ambisonic format. The book comes with various practical examples based on free software tools and open scientific data for reproducible research. The book’s introductory section offers a perspective on Ambisonics spanning from the origins of coincident recordings in the 1930s to the Ambisonic concepts of the 1970s, as well as classical ways of applying Ambisonics in first-order coincident sound scene recording and reproduction that have been practiced since the 1980s. As, from time to time, the underlying mathematics become quite involved, but should be comprehensive without sacrificing readability, the book includes an extensive mathematical appendix. The book offers readers a deeper understanding of Ambisonic technologies, and will especially benefit scientists, audio-system and audio-recording engineers. In the advanced sections of the book, fundamentals and modern techniques as higher-order Ambisonic decoding, 3D audio effects, and higher-order recording are explained. Those techniques are shown to be suitable to supply audience areas ranging from studio-sized to hundreds of listeners, or headphone-based playback, regardless whether it is live, interactive, or studio-produced 3D audio material.

Handbook of Signal Processing in Acoustics