Recommendation ITU-T P.835 (07/2026) Subjective test methodology for evaluating speech communication systems andterminals providing noise suppression functionality
Summary
History
FOREWORD
Table of Contents
Introduction
1 Scope
2 References
3 Definitions
     3.1 Terms defined elsewhere
     3.2 Terms defined in this Recommendation
4 Abbreviations and acronyms
5 Conventions
6 Experimental design
     6.1 Overview
     6.2 Speech material
     6.3 Assessment of test conditions
          6.3.1 General
          6.3.2 Acoustical insertion (Terminals)
          6.3.3 Electrical insertion
          6.3.4 Offline simulation
          6.3.5 Sample calibration strategies
     6.4 Reference conditions
     6.5 Listening test sessions
          6.5.1 Listeners
          6.5.2 Audio presentation
          6.5.3 Instructions and rating scales
          6.5.4 Speech sample presentation
          6.5.5 Voting process and data collection
     6.6 Reporting of test results
          6.6.1 Summary results
          6.6.2 Score profiles
          6.6.3 Analysis methods
Annex A  Reference conditions
     A.1 General
     A.2 Reference conditions based on MNRU
     A.3 Reference conditions based on spectral subtraction
Annex B  Spectral subtraction method for controlled musical tone degradations
     B.1 Introduction
     B.2 Processing steps
     B.3 Relation between quality and processing parameters
Appendix I  Procedure for proper mixing of speech and noise samples
     I.1 General
     I.2 Parameters
     I.3 Speech and background noise files
     I.4 Speech and noise input filters
     I.5 ITU-T P.56 speech level adjustment
     I.6 Basic noise level adjustment
Appendix II  Example of instructions to subjects
     II.1 Instructions
Appendix III  Additional provisions for nonstationary noise suppressors
     III.1 General
     III.2 Usage mode
     III.3 General recording properties
     III.4 Speech source recordings
     III.5 Noise source recordings
     III.6 Signal-to-noise ratios
     III.7 Post-processing by voice codec
     III.8 Initial convergence time
     III.9 Test types
     III.10 Example: Acceptance test format recommendations
Bibliography