Doyuen Ko

Rendering an immersive sound field using a virtual height loudspeaker: Effect of height-related room impulse responses

In order to provide consumers more enhanced and immersive experience in sound, most of the new multichannel reproduction formats highlight the significance of height-related information. In this paper, we investigated the influence of height-related room impulse responses when reproduced via various “height-loudspeakers,” including a virtual loudspeaker. Test participants listened to the corresponding sound fields and rated their perceived quality in terms of spaciousness and integrity. The results showed that perceived quality was affected by height loudspeaker positions and height signals, which was a specific room impulse response coupled with a virtual loudspeaker rendering process.

Towards the state of the art in virtual acoustics technology

Active acoustics enhancement systems have been applied in room acoustics for decades yet it would be hard to say that their ultimate performance has been achieved, even with the power of today’s fast digital processors. There are many challenges ahead including the creation of homogeneous directionless diffuse field using a limited number of discrete loudspeaker sources. There is also a need to create soundfield having some localized directional properties mimicking the phenomena found in acoustics of musical instruments interfacing the acoustics of rooms. Some solutions to these challenges will be presented and discussed by the authors.

A new active acoustics system for enhancing musician's environment on concert and recording stages

The necessity of variable acoustics in modern performance spaces is widely acknowledged; particularly, there has been a growing interest in active acoustics enhancement systems. Many different systems have been developed and installed in concert halls, public venues, and research facilities worldwide. However, further improvements are required to provide musicians with a desirable acoustic on-stage support equal in quality to the best rooms. An innovative electro-acoustic enhancement system, based on measured high-resolution impulse responses, is developed at the Virtual Acoustics Technology (VAT) lab, in McGill University. The first model is installed in Multi-Media Room (MMR), a large rectangular space (80 ft. × 60 ft. × 50 ft.) designed as a film scoring stage. The system uses an array of omni-directional radiators and its signal processing includes 24-channel low-latency convolution at 24 bit/96 KHz, three separate stages of matrix mixing, equalization, and time variation. The objective measurement of...

Virtual acoustic environments for music performance, rehearsal, and recording

A comprehensive 24-channel sound field rendering system was built at McGill University’s CIRMMT Centre to immerse scholar/performer Tom Beghin in virtual concert spaces where Haydn composed and performed his keyboard sonatas, or expected them to be performed. The virtual rooms were reconstructed from detailed measurements made in Haydn’s historical rooms in Europe using a high-resolution 24bit/96kHz impulseresponse measuring system. In an acoustically treated laboratory, 24 custom loudspeaker arrays were arranged on a surface of a hemisphere surrounding the performer. Multiple fast DSP engines convolved live signals with 24 impulse responses allowing the performer to rehearse and record in each room with low-latency virtual acoustics. This paper describes the details of system design, the method of measurement, and discusses various aspects of recording and performing in virtual acoustic environments. The method has also been tested in a large room during public performance by having virtual-room responses and high-definition photo images projected from the stage. Surround sound recordings of Haydn’s complete solo keyboard music made in several virtual rooms and matched to specific historical instruments will be released in a collection of 13 commercial SA-CD’s by the end of 2008.