Tuesday, May 23, 10:30 — 12:30
Will Howie (Chair)
P23-01 Subjective Evaluation of Orchestral Music Recording Techniques for Three-Dimensional Audio
Will Howie (Presenting Author), Florian Grond (Author), Richard King (Author), Denis Martin (Author)
A double-blind study was conducted to evaluate a recently developed microphone technique for three-dimensional orchestral music capture, optimized for 22.2 Multichannel Sound. The proposed technique was evaluated against a current 22.2 production standard for three-dimensional orchestral music capture, as well as a coincident, higher order ambisonics capture system: the Eigenmike. Analysis of the results showed no significant difference in listener evaluation between the proposed technique and the current production standard in terms of the subjective attributes “clarity,” “scene depth,” “naturalness,” “environmental envelopment,” and “quality of orchestral image.”
Convention Paper 9797
P23-02 Formal Usability Evaluation of Audio Track Widget Graphical Representation for Two-Dimensional Stage Audio Mixing Interface
Christopher Dewey (Presenting Author), Jonathan Wakefield (Author)
The two-dimensional stage paradigm (2DSP) has been suggested as an alternative audio mixing interface (AMI). This study seeks to refine the 2DSP by formally evaluating graphical track visualization styles. Track visualizations considered were text only, circles containing text, individually colored circles containing text, circles color coded by instrument type with text, icons with text superimposed, circles with RMS related dynamic opacity, and a traditional AMI. The usability evaluation focused on track selection efficiency and included user visualization preference for this micro-task. Test subjects were instructed to click five randomly selected tracks for a six, sixteen, and thirty-two track mix for each visualization. The results indicate text only visualization is best for efficiency however test subjects preferred icons and traditional AMI.
Convention Paper 9798
P23-03 In-Ear vs. Loudspeaker Monitoring for Live Sound and the Effect on Audio Quality Attributes and Musical Performance
Jan Berg (Presenting Author), Tomas Johannesson (Author), Magnus Löfdahl (Author), Arne Nykänen (Author)
A successful performance of live music is dependent on how well musicians can hear themselves and the other members of the ensemble. Sound reinforcement systems can offer monitoring either by on-stage loudspeakers or in-ear headphones. These two monitoring conditions were compared to search for perceived auditory differences that affect parts of musical performance. Four jazz/pop/rock bands made live performances where monitor sound was provided to the musicians. Each band repeated their performance, changing from one monitoring condition to the other. After every performance, the musicians responded to questionnaires covering musical performance and audio quality. Experts also assessed recordings of the performances. Results show that perceived differences exist in audio quality and musical performance between loudspeaker monitors and in-ear headphone monitors.
Convention Paper 9799
P23-04 Using a Speech Codec to Suppress Howling in Public Address Systems
David Ditter (Presenting Author), Edgar Berdahl (Author)
Acoustical feedback is present whenever a loudspeaker signal gets redirected to a microphone that feeds its input signal directly or indirectly back into the loudspeaker. If the gain around such a closed feedback loop is close to or higher than unity, unpleasant acoustical artifacts will typically occur and will nearly always lead to a periodic howling sound. Most readers are probably familiar with this noise, which can for example set in when a microphone is accidentally pointed at a speaker. This research project aims to suppress these unwanted effects of acoustical feedback by the insertion of a modified speech coder and decoder into the signal path of the feedback loop. It is demonstrated that the Speex open-source speech codec can be successfully tweaked to increase the maximum stable feedback gain by as much as 3 dB to 7 dB through adjustment of the codec’s quality parameter. This enhancement outperforms the simple introduction of shaped noise into the feedback loop and is compared with the performance of a frequency shifter. Tests are conducted using an automated experimental framework for determining the maximum stable gain of a public address system.
Convention Paper 9800