Beyond "Basic Audio Quality": Evaluating the perceived quality of spatial audio codecs
Research Student: Dr Paulo Marins
Principal Supervisor: Prof Francis Rumsey
Co-Supervisor: Dr Slawek Zielinski
Supported by: CAPES, Ministry of Education of Brazil
Start date: 2005
End date: 2009
The main aim of this project was to characterize the perceptual effects introduced by low bit rate spatial audio codecs. The existing methodologies used to evaluate spatial audio codecs were reviewed and the most important studies conducted to assess the perceived quality of spatial audio coding systems were compared. It was found that spatial audio codecs have been evaluated according to ITU-R standards BS.1116 and BS.1534. These tests evaluate the performance of audio codecs using one perceptual attribute – basic audio quality (BAQ). This approach, although effective in terms of the assessment of the overall performance of codecs, does not quantify the contribution of typical codec distortions to the perceived BAQ of the codecs or allow for the identification of independent perceptual attributes that describe the artefacts introduced by spatial audio coding systems.
A series of experiments was carried out aiming to characterize the perceptual effects introduced by low bit rate spatial audio codecs. Two initial studies were conducted with the intention of investigating the contribution of selected attributes to the BAQ of low bit rate spatial codecs. Furthermore, another two experiments were performed in order to identify the perceptually salient dimensions or the independent perceptual attributes related to the artefacts introduced by low bit rate spatial audio coding systems.
It was found that impairments related to timbral features of the sound are the ones that affect the most the perceived basic audio quality of the codecs. Additionally, two perceptually salient dimensions and four independent perceptual attributes were uncovered providing a description of the perceptual effects introduced by low bit rate spatial audio codecs.
- P. Marins, F. Rumsey, and S. Zielinski. Uncovering the multidimensional perceptual space of low-bit rate multi-channel audio codecs. Presented at the Reproduced Sound 24/Institute of Acoustics Conference, Brighton, United Kingdom, 20-21 Nov 2008.
- P.Marins, F.Rumsey, S.Zielinski "Unravelling the Relationship Between Basic Audio Quality and Fidelity Attributes in Low Bit-Rate Multi-Channel Audio Codecs", AES 124 Convention (May 2008)
- P.Marins, F.Rumsey, S.Zielinski, "The Relationship between Basic Audio Quality and Selected Artefacts in Perceptual Audio Codecs - Part II: Validation Experiment", AES 122 Convention (May 2007)
- P.Marins, F.Rumsey, S.Zielinski,
"The Relationship between Selected Artifacts and Basic Audio Quality in Perceptual Audio Codecs",
AES 120 Convention (May 2006)
Full text available at: epubs.surrey.ac.uk/544