User's Manual Part 2

Nomad User’s Manual Appendix D – PESQ Tools GUI Case Study
Copyright © Spirent Communications, Inc. 2013 151
The Reference and Degraded Signal spectrums available in the PESQ Tools GUI provide another
means of analysis. These figures can be used to visually compare the reference to the degraded
frequency response. Note that although this example exhibits frequency fade above 3.5 kHz, this is
a normal response for mobiles calling the Audio Server and is not expected to affect the MOS
outcome.
Figure D-6 - Reference and Degraded Signal Spectrums
The buzzing, clipping and frequency response characteristics are all apparent upon comparison of
the Reference Spectrogram to the Degraded Spectrogram. The Spectrogram graphs provide
frequency spectra information over the duration of the sample.
Figure D-7 - Reference Spectrogram