11,602,207,002,40 11,60 5,60 1,00 1,20 7,80 Practical Limitations of Wideband Terminals Workshop on Wideband Speech Quality in Terminals and Networks: Assessment and Prediction 8 th and 9 th June 2004 – Mainz Germany Dr.-Ing. Carsten Sydow Siemens AG

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 2 Introduction wideband was standardized in the 90s by ETSI for ISDN terminals becomes more popular with the proliferation of PC based IP telephony (Skype) finds it‘s way into conventional telephony systems (Siemens optiPoint 410) high quality wideband codecs G.722, G.722.1, G.722.2, iLBC... are available Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 3 applicable standards (list not complete) main differences between wideband and narrowband standards  frequency response mask  type of artificial ear for handset measurements minor differences  distortion and noise requirements Wideband Standards operating mode countrynarrowbandwideband handsetEuropeTBR8I-ETS USATIA 810ATIA 920 hands freeEuropeI-ETS I-ETS USATIA 810ATIA 920 Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 4 Frequency Response Mask: Handset Sending Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 5 Frequency Response Mask: Handset Receiving Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 6 Frequency Response Mask: Hands-Free Sending Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 7 Frequency Response Mask: Hands-Free Receiving Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 8 Frequency Response Masks: Discussion main differnce: extension of frequency range from 300 Hz 3400 Hz to 160 Hz to 6300 Hz practical problem lies in the low frequency extension significant differences between European and US standards  Europe: higher bandwidth Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 9 Artificial Ear for Wideband Measurements TBR8: type 1 (optional type 3.2 ll) TIA 810A: „suitable“ ear I-ETS : 3.2 ll or 3.3 (depending on handset geometry) TIA 920: not type 1 leakage effect: Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 10 typical handset receiver response frequency response tuned to meet narrowband requirements ( 3 resonances ) closed back volume high mechanical impedance side conditions: cost, robustness, HAC, weight  receiver cannot be easily modified to meet the wideband requirements Suitability of conventional transducers: Receiver Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 11 Suitability of conventional transducers: Speaker typical 50 mm speaker response resonance frequency > 300 Hz stiff membrane suspension, small size (small wight), small magnet Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 12 Suitability of conventional transducers: Speaker for Mobile Terminal response of a 36 mm diameter speakerIntroduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion

© Siemens, ,602,207,002,40 11,60 5,60 1,00 1,20 7,80 ETSI Wideband Workshop, C.Sydow, Seite 13 Conclusion conventional receivers and speakers cannot transmit the whole „wideband“ frequency range even small extension of the narrowband frequency range lead to significant improvements in speech quality ad intelligibility wideband telephony will only get into the market if additional cost is low  several degrees of wideband (1, 2, 3)  take care of spectral balance !!!  take care of leakage sensitivity  E-model and objective quality measurements have to rate frequency range, spectral balance and leakage sensitivity Introduction Standards Response Masks  Handset sending  Handset receiving  Hands free sending  Hands free receiving  Discussion Artificial Ear Conventional Transducers  Receiver  Speaker  Speaker mobile terminals Conclusion