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VQT - Voice Quality Testing

Call quality can be affected by noise, distortion, too high or low signal volume, echo, gaps in speech, and a variety of other problems. The emutel™ Harmony measures voice quality indicators (PESQ, MOS and R-factor) along with the impairments which can affect these (delay, packet loss, signal level, noise level and SNR) capturing the data for each call to gain further insight into voice quality issues.

Measurements taken are compliant with ITU-T P.862.x, giving the ability to test narrowband as well as wideband audio signals. Our Voice Quality Tester provides accurate and repeatable measurements of speech quality through a network, whether telephony or IP based. It compares the audio signal inputted into a network with the corresponding, degraded, audio signal outputted from the network.

Main Features

  • ITU-T P.862.x Perceptual Evaluation of Speech Quality, with mapping to MOS scale
  • Narrowband and Wideband operation
  • Delay measurement and statistics - min, max, average delay along with delay vs. Time, on a per call basis
  • Spectrum Analysis for the dB levels of Narrowband and wideband signals
  • Inbuilt IRS filtering
  • Exhaustive statistics, call records, graphs
  • Ability to listen to the source and recorded audio files
  • Remote access to results via web-browser or command line interface
  • Ability to play custom wav file


ETSI Standard Measurements and Reports

We are measuring end to end quality according to ETSI measurement standards:

  • Setup Through
  • Setup Connection time
  • Setup Acknowledge
  • Wait for Ring
  • One Way Delay
  • SNR
  • Narrowband MOS and PESQ
  • Dropouts
  • Connect Through
  • Disconnect Through
  • Clear Down
  • Duration
  • Delays
  • V.17 & V.34 Fax quality
  • POLQA (P.863)
  • Jitter
  • Alert Through
  • Setup Confirm
  • Wait for Answer
  • Post pickup and dial delay
  • PESQ (ITU-T rec. P.862.2)
  • MOS - LQO (ITU-T rec. P.862.1)
  • R-factor (g.107)
  • Wideband E-model (G.107.1)

Reports can be generated for each test carried out on the Harmony.

All the results are available as Excel and CSV file via Command Line Interface and web-browser.

Error messages can be send as SNMP traps to your Network Overview Server whenever outside parameters.

PESQ worldwide recognized standard

Any device used in speech telecommunication, whether ISDN, PSTN, VoIP or mobile, needs to have good voice quality for it to be a successful product in the marketplace. But how do we determine good, or bad, voice quality?

The emutel™|Harmony uses the PESQ algorithm for quality measurements which adheres to the ITU-T P.862.1 and P.862.2 standards.

PESQ is a full-reference algorithm which analyses the speech signal sample-by-sample after a temporal alignment of corresponding excerpts of the reference and test signal. PESQ can be applied to provide an end-to-end (E2E) quality assessment for a network, or characterize individual network components.

PESQ results principally model mean opinion scores (MOS) that cover a scale from 1 (bad) to 5 (excellent). A mapping function to MOS-LQO is outlined under P.862.1.