Jürgen Herre

On the validity of virtual reality-based auditory experiments: a case study about ratings of the overall listening experience

In recent years, new developments have led to an increasing number of virtual reality (VR)-based experiments, but little is known about their validity compared to real-world experiments. To this end, an experiment was carried out which compares responses given in a real-world environment to responses given in a VR environment. In the experiment, thirty participants rated the overall listening experience of music excerpts while sitting in a cinema and a listening booth being in a real-world environment and in a VR environment. In addition, the VR system that was used to carry out the sessions in the VR environment is presented in detail. Results indicate that there are only minor statistically significant differences between the two environments when the overall listening experience is rated. Furthermore, in the real-world environment, the ratings given in the listening booth were slightly higher than in the cinema.

Evaluation of Spatial/3D Audio: Basic Audio Quality Versus Quality of Experience

During the past decades, spatial reproduction of audio signals has evolved from simple two-channel stereo to surround sound (e.g., 5.1 or 7.1) and, more recently, to three-dimensional (3D) sound including height speakers, such as 9.1 or 22.2. With increasing number of speakers, increasing spatial fidelity and listener envelopment are expected. This paper reviews popular methods for subjective assessment of audio. Moreover, it provides an experimental evaluation of the subjective quality provided by these formats, contrasting the well-known basic audio quality (BAQ) type of evaluation with the more recent evaluation of overall listening experience (OLE). Commonalities and differences in findings between both assessment approaches are discussed. The results of the evaluation indicate that 3D audio enhances BAQ as well as OLE over both stereo and surround sound. Furthermore, the BAQ- and OLE-based assessments turned out to deliver consistent and reliable results.

The Influence of Audio Quality on the Popularity of Music Videos: A YouTube Case Study

Video-sharing websites like YouTube contain many music videos. On such websites, the audio quality of these music videos can differ from poor to very good since the content is uploaded by users. The results of a previous study indicated that music videos are very popular in general among the users. This paper addresses the question whether the audio quality of music videos has an influence on user ratings. A generic system for measuring the audio quality on video-sharing websites is described. The system has been implemented and was deployed for evaluating the relationship between audio quality and video ratings on YouTube. The analysis of the results indicate that, contrary to popular expectation, the audio quality of music videos has surprisingly little influence on its appreciation by the YouTube user.

Chapter 28 – Perceptual Audio Coding

Abstract Audio Coding has proliferated as a mainstream enabling digital technology for all types of applications that provide audio and multimedia to consumers using transmission or storage channels with limited capacity. Since its infancies in the eighties and early nineties, the technology behind low bitrate audio coding has developed rapidly until today. Nonetheless, the technology generations seen to date follow several common themes, including the use of time/frequency-domain processing, redundancy reduction (entropy coding), and irrelevancy removal through the pronounced exploitation of perceptual effects. The latter aspect is of paramount importance to the understanding and the performance of the coding systems and has gained more and more in importance over time. Starting from basic principles, this article provides an overview of methods for low bitrate perceptual audio coding and its evolution over time along with some related coding standards (e.g., “mp3”) and typical applications.