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Speech Quality Measurement Systems

Malden. Electronics. Speech Quality Measurement Systems. 1. Malden Electronics. Privately-owned, specialising in the development of speech performance measurement equipment Established over 30 years Located in South West London, UK

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Speech Quality Measurement Systems

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  1. Malden Electronics Speech Quality Measurement Systems 1 Malden Electronics

  2. Privately-owned, specialising in the development of speech performance measurement equipment Established over 30 years Located in South West London, UK 25 years’ experience in speech performance measurements for telecommunications Quality system certified to ISO9001:2008 International customer base includes all major telecommunications equipment manufacturers, operators of telecommunication networks and service providers. Malden Electronics

  3. Users span telecomms industry

  4. Customers - 1

  5. Customers - 2

  6. Control and management software Hardware and software end points interfacing to network or network components What is MultiDSLA?

  7. Server MultiDSLA MultiDSLA MultiDSLA MultiDSLA Architecture Control Speech Network Results Test Interface (“Node”)

  8. New York Paris Madrid São Paulo Seoul Istanbul Hong Kong Mexico City Tokyo London Singapore New York Moscow Athens Tel Aviv Buenos Aires New Delhi Sydney Düsseldorf Toronto MultiDSLA scales to test one segment or the entire speech network A simple map represents real-world locations Each “node” is an analogue, digital or SIP/H.323 test interface

  9. Node Component: Digital Speech Level Analyser (DSLAII) • High Quality Instrument • Proven in many applications • Two analogue channels • High speed Ethernet • Connect to analogue lines, IP phone handset cord, soft phone (PC sound card), mobile phone, etc. • Outputs for control of external devices (mobile “button”, push-to-talk, handset lifter, etc.)

  10. VN Node Component: Virtual Node (VN) • Windows application • Permanent or semi- permanent installation • “Reference soft phone” • SIP & H.323 protocols • Codec support • QoS support • RFC 2833 support

  11. ISDN Node Component: Basic Rate/Primary Rate ISDN • Windows application and cards • Concurrent Speech Quality Measurements on all channels

  12. Node Component: Conference • Phantom node that can have dial-in properties of a conference bridge • Supports passwords for access control • Can also be used for IVR testing

  13. Metrics

  14. Signal Measurements • Speech Level ITU-T Rec. P.56 • Noise • DTMF

  15. DTMF Analysis

  16. Intrusive Metrics

  17. Speech Quality ITU-T Rec. P.862.1/2 • One Way Delay • Echo Level and Delay • Acoustic Performance ITU-T Rec. P.310/311 • E-Model ITU-T Rec. G.107

  18. Echo Level and Delay

  19. The listening quality and listening effort score is based upon a five point category judgement scale defined in ITU-T Rec P.800: Listening Quality Lq Listening Effort Le 5 Excellent Complete relaxation possible; no effort required 4 Good Attention necessary; no appreciable effort required 3 Fair Moderate effort required 2 Poor Considerable effort required 1 Bad No meaning understood with any feasible effort

  20. Objective Listening Test Techniques • PSQM ITU-T Rec. P.861 - designed for codec evaluation. • Assesses error loudness, noise disturbance and asymmetry to predict a PSQM value • Withdrawn February 2001 • PAMS – developed for real world networks • Assesses time aligned, level aligned, spectrally weighted error surface • PESQ - ITU-T Rec. P.862 Perceptual Evaluation of Speech Quality • Combining PAMS and new version of PSQM • PESQ - ITU-T Rec. P.862.1 MOS-LQO Mapping • Improved correlation with MOS • PESQ - ITU-T Rec. P.862.2 Wideband Mapping

  21. Determine the Listening Quality score using PESQ

  22. Auditory Model • Reproduces the gross psychophysical properties of hearing • Sensory Layer • Perceptually relevant comparison • Subjectivity of audible errors • Perceptual Layer • Speech quality metric

  23. Auditory Sensory Model Auditory Stimulus Frequency to pitch Level to sensation Simultaneousmasking Temporal masking Representation as specific loudness pattern

  24. Auditory sensation surface

  25. Audible error surface

  26. Perceptual Evaluation of Speech Quality • PESQ Score • Defined on scale 4.5 to -0.5 • Range 4.5 to 1.0 correlates with Lq or MOS • PESQ-LQ and P.862.1 Score

  27. PESQ • Level alignment • Filter • Time align • Equalise • Transform • 32msec overlapping frames • Bark spectrum for active speech frames • Spectral equalisation of reference signal and elimination of gain variations • Map to Sone loudness scale • Assess disturbance • Evaluate difference accounting for masking, deletion and asymmetry • Aggregate disturbances over time • Realign bad intervals where delay change may have occurred • Model and map to MOS

  28. PESQ Correlation • ITU-T database MOS correlation with PESQMOS 93.5%

  29. Momentary loss of speech in VoIP network

  30. LAN with no load. Speech quality moderate VoIP and Network Load

  31. LAN with no load. Speech quality moderate LAN with load. VoIP and Network Load

  32. Voice activity detector

  33. Delay variations

  34. G.729 8kbps G.711 64kbps G.723 5k3bps G.723 6k3bps Codec Performance

  35. Test Scenarios • Wireline • VoIP • Conference • Network/Enterprise • Mobile

  36. Measuring the Delay in the Speech Path across Networks

  37. Wireless Network Delay = ?

  38. Channel A Channel B Digital Speech Level Analyser II Malden Electronics Ltd MultiDSLA Wireless Network Delay = PESQ time offsetP.862.1 = 3.8 Speech Quality Analysis for Wireless Networkwithout GPS

  39. Channel A Channel A Channel B Channel B Digital Speech Level Analyser II Digital Speech Level Analyser II Malden Electronics Ltd Malden Electronics Ltd MultiDSLA MultiDSLA Wireless Network • Delay Error due to • Synchronisation of PC clocks • Control Path Delay • Windows Speech Quality Analysis for Wireless Networkwithout GPS

  40. Channel A Channel A Channel B Channel B Digital Speech Level Analyser II Digital Speech Level Analyser II Malden Electronics Ltd Malden Electronics Ltd MultiDSLA MultiDSLA Wireless Network E3 delay = 245msPESQ time offset = 477msP.862.1 = 3.8 PESQ time offset = -23msP.862.1 = 3.6 Speech Quality Analysis for Wireless Networkwithout GPS

  41. Channel A Channel A Channel B Channel B Digital Speech Level Analyser II Digital Speech Level Analyser II Malden Electronics Ltd Malden Electronics Ltd MultiDSLA MultiDSLA Wireless Network GPS GPS E3 delay = 245msPESQ time offset = 131msOne-way delay = 131msP.862.1 = 3.8 PESQ time offset = 114msOne-way delay = 114msP.862.1 = 3.6 Speech Quality Analysis for Wireless Networkwith GPS

  42. Test Scenarios • Wireline • Mobile • VoIP • Conference • Network/Enterprise • Acoustic

  43. Results

  44. Connections Report – shows that speech quality problems occurred in one direction of the call only.

  45. Remote Access • Control MultiDSLA using • TCL • Perl • Python • HyperTerminal • TCP/IP tunnel • Providing • User Logon • Node Management • Call Management • Test Management • Results Extraction • Results Analysis • Utility Functions

  46. Result Access – Remote Access • Simple command API • XML output • RESULT GETLIST 3 PESQ, LEVELS, GPS Test Id

  47. KPI – Key Performance Indicators User-defined Measurements

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