Table of Contents

 1     Scope          
 2     References               
 3     Terms and definitions           
 4     Abbreviations and acronyms             
 5     Characteristics of VEDs         
        5.1     General            
        5.2     Acoustic echo control (AEC)    
        5.3     Noise reduction (NR) 
        5.4     Tandem free operation (TFO)
        5.5     Interworking functions (IWF) 
 6     Test signals
        6.1     General            
        6.2     Measuring input and output signal levels          
        6.3     Gaussian white noise 
 7     Tests            
        7.1     Overall VED tests         
        7.2     Noise reduction tests 
        7.3     Acoustic echo control tests      
 8     Conformance and interoperability  
        8.1     Mandatory tests          
        8.2     Optional tests
        8.3     Interoperability            
Appendix I – Information on the function and location of VEDs in mobile networks    
        I.1                   VED functionality            
        I.2                   VED location      
        I.3                   CTM operation 
Appendix II – Objective measures for the characterization of the basic functioning of noise reduction algorithms    
       II.1     Introduction   
       II.2     Notations         
       II.3     Test signals      
       II.4     Objective measures for characterization of NR algorithm effect              
       II.5     Recommendation values for SNRI, TNLR and DSN         
       II.6     Reference software    
Appendix III – Properties of level measurement devices    
      III.1     Introduction   
      III.2     Measurement of signal level   
      III.3     Transition time for measurement device with exponential averaging   
      III.4     Transition time for RMS measurement device
      III.5     Comparing the levels of two signals (exponential averaging)    
      III.6     Comparing the levels of two signals (RMS method)      
      III.7     Artificial speech signal in noise               
      III.8     Conclusions    
Appendix IV – One-octave filters for the AEC comfort noise test    
       IV.1     Introduction  
       IV.2     IIR realization
       IV.3     FIR realization