Acoustic Testing Model - Perceived Spatial Quality of Sound Processing and Reproducing Equipment




Current models of audio testing measure `basic audio quality', using subjects to judge any difference. This leads to a perceived magnitude of distortions and a subjective acceptability.


The QESTRAL acoustic testing model looks at any and all difference in the spatial attributes.



  • Reduce the number of listening tests, which are resource intensive.
  • Evaluate the effects of different forms of spatial rendering
  • Algorithms for optimisation of sound reproduction systems
  • Measure the spatial impairment introduced by audio processors, transmission systems or codecs.
  • Extend existing standard quality models
  • Increase efficiency of industrial development process
  • Online check of broadcast quality


  • Audio Standards


Available for licence

Demonstrator Available


IP status

Patent Pending



This has been developed over a 3 year period in collaboration between the University of Surrey, BBC R&D and Bang & Olufsen.


Two multi-stimulus listening tests were used to collect listeners┬┐ judgements of spatial quality to calibrate the regression model. The test used 31 listeners, 43 degradations, 3 types of programme material and 2 listening positions.


The model was calibrated using least-squares regression, with a fixed constraint at the top of the scale. A leave-one-out cross-validation gave R2 = 0.78 and a root-mean-squared error of prediction (RMSEP) of 12.0%.

Patent Information:
For Information, Contact:
Uduak Koka
University of Surrey
Uduak Koka
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