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Digital Speech Level Analyser. The information you need about speech performance. What is the DSLA? Artificial Speech Test Stimulus – Phonytalk ™ Scripting Speech Quality Assessment Sample Results DSLA Users Support. What is the DSLA?
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Digital Speech LevelAnalyser The informationyou need about speech performance
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
A precision analogue instrument Purpose-designed (not a PC soundcard) 24-bit A-D & D-A Noise floor below -80dBm Better than 110dB dynamic range Advanced analysis software Digital connection add-ons for ISDN and VoIP What is the DSLA? “The best quality platform available”
Analysis Software • Voice measurement • Signal analysis • User task scripting • Task scheduling • Graphical output • Data logging • And much more…
Using DSLA Analogue Ports Digital Speech Level Analyser A RAM D/A Network B DSP A/D
Network Under Test PBX DSLA DSLA temporarily replaces the telephone. DSLA Ethernet Analysis of Speech Quality in a Network via Analogue PBX Ports • Speech Quality Score(s) • Mean, Max, Min Delay • Echo Level, TERL • Speech Level • Noise Level • etc. FXS ports
IP Network DSLA temporarily replaces the handset. DSLA DSLA Application: End to End Testing of Speech Performance via Handset or Headset Ports PC
IP Network Another Network Remote testing between two sites
VN Using one Analogue Port and one VN Digital Speech Level Analyser A RAM D/A (IP) Network DSP A/D “B”
VN VN “A” Using two VN’s Digital Speech Level Analyser RAM D/A (IP) Network DSP A/D “B”
ISDN Using one Analogue Port and one ISDN Port Digital Speech Level Analyser Telephony Network A RAM D/A DSP A/D Data (IP) Network “B”
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
Artificial Speech Test Stimulus • Representative sounds and transitions between sounds from a conversational database • Efficiency by elimination of redundancy • Spectral and temporal properties are speechlike
A linguistically motivated artificial speech test • signal in different languages American English Female Male British English Female Male
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
Using speech signals, measure in real-time: • delay • echo level, • TERL • noise
A Scheduler automates complex test routines …. • Avoids tedious • manual repetition • Permits unattended • operation • facilitates remote • testing
…. and gives you full control Each task defines: • Either one or two playlists • and the channel settings • When execution takes place • How many times
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
Measure, repeatably, the mean active speech level • - ITU Recommendation P.56 Method B Instantaneous peak signal level Test duration Noise measured in silent intervals True RMS average level over test duration Percentage of time mean active speech level is exceeded, i.e. speech is present Mean active speech level Input signal source Selected units
What call quality do you get before and after voice/data integration? Why not ask the users…?
“It sounds a bit distorted” “… sounds alright to me” “There’s more delay before you hear the reply” “It was OK last week, but this week it’s been terrible” “Sometimes there are bits missing” “It sounds awful” “All that money and it’s worse than before” “What’s that buzzing noise?” “I can hear my own voice echoing” “I’m sure it used to be clearer” “Well, it’s better than GSM” “There’s this sort of warbling sound” “You wait ages for the call to go through”
Comparison of IP phone performance Mean PESQ-LQ score Mean delay A-B (ms) Stddev. of PESQ-LQ scores Mean delay B-A (ms) Brand A G.711 Brand B G.711 Brand B G.729
Speech Quality Assessment • PAMS • PSQM / PSQM+ • PESQ (ITU-T Recommendation P.862) • PESQ LQO extension P.862.1
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
DSLA Speech Quality Display MOS prediction Reference surface – transmitted signal Degraded surface – received signal Error surface
G.729 8k bps G.711 64k bps G.723 5k3 bps G.723 6k3 bps Effects of Compression
LAN with no load. Speech quality moderate LAN with data load. Speech quality poor. Packet loss visible as negative excursions in the error surface; loss of synchronisation near end produces loud ‘squeak’ effect Effect of Data Loading on LAN used for VoIP
The zoom view makes clear a 20ms packet loss which has not been concealed. The loss occurs in the fourth utterance This is a packet loss of 100ms duration. Again, there is no concealment Other Common VoIP Problems
Utterance marker #5 appears in a segment of active speech. This indicates that jitter buffer re-sizing has occurred The utterance offset (delay) histogram shows that the jitter buffer was increased in size by about 6ms Other Common VoIP Problems
The 2-D view shows some disturbance at the beginning of the second utterance The corresponding utterance histogram shows the jitter buffer has been re-sized in increments of 10ms, then a decrement of 20ms Other Common VoIP Problems
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
3COM Acoustic Technologies Acterna Zurich AG Advanced Fiber Communications Advanced TelCom Group Agere Systems Airbiquity Inc Alcatel Alcatel Bell Ambit Microsystems Corp Ameritec Corporation Analog Devices AOL Arkon Technologies Arthur Andersen Askey International Astrium AT & T Atlinks ATMEL AudioCodes Avaya AVM Barclays Global Investors BCM Computers Belgacom Bell Atlantic Mobile BellSouth Binatone Birch Telecom Broadcom BT Cable & Wireless Cablevision Cambridge Silicon Radio Carleton University CCT Telecom Centillium Cetacean Networks Cetecom Cisco Systems Clarity Clarus Systems Comdial Comverse Concert Communications Conexant Consumer Union CT Labs Data Connection/MetaSwitch Dataflow Systems DBTEL International Denso International DFS (German Air Traffic Control) Dilithium Dolphin Telecommunications Doro Audioline Dynamicsoft EADS Defence & Security Networks Efficient Networks Ericsson eStara Finnish Air Force FirstMark Communications France Telecom G3 Nova General Bandwidth General Instrument GL Communications Global China Technology Global Crossing Global One Goldman Sachs GTE Internetworking Honeywell Hughes Network Systems ICF Consulting IDT InnoMedia Intel Corporation Intelsat IP Axess Iridium ITO ITS Ixia Jetstream KTL Kingston inbusiness Latitude Communications Legerity Lernout & Hauspie Level 3 LSI Logic Corporation Lucent Technologies Macronix Marconi Matra Nortel Médiatrix Mentor Graphics Milgo Solutions Mindspeed Technologies Ministry of the Interior, France Ministry of Defence, UK Mitel Motorola National Air Traffic Services Net2Phone Netergy Network Equipment Technologies Next Level Communications Nexus Telecom NMS Communications Nokia Nortel Networks Octasic Inc OnStar Opuswave Panasonic Plantronics Polycom PrairieCom Racal Rockwell Collins RSI Sagem Salix Sentito Sepura Siemens Simoco Europe Smiths Industries South West Research Inst Sprint Sun Corp Swisscom Symbol Technologies T-Mobile (UK) Team Concepts Tecom Telesync, Inc Tellabs Telmax Telogy Telspec Telstra Telus Mobility Texas Instruments Thales Group The Mitre Corporporation Thomson Multi Media Inc Tollbridge Networks University of Ghent University of Ottawa U.S. Department of Defence U.S. Department of State UTStarcom Verizon Virata VocalData Vodafone VodTel VTech Communications Worldwide Data Systems Speech Performance Measurement System Users
What is the DSLA? • Artificial Speech Test Stimulus – Phonytalk™ • Scripting • Speech Quality Assessment • Sample Results • DSLA Users • Support
Digital Speech Level Analyser Technical Support – Free of charge, without time limit, by email or telephone Software Updates – Free of charge, no need for contract, without time limit Malden Electronics holds ISO 9000: 2000 certification