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Abstract

Telecommunications Industry Association TR41.3.3-07-11-005-M. Abstract

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Abstract

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  1. Telecommunications Industry Association TR41.3.3-07-11-005-M Abstract Based on IEEE STIT’s discussion at its Santa Cruz meeting, STIT created a PowerPoint slides for Allen Woo to present it at ETSI STQ meeting in last September. The presentation was further submitted to ITU-T SG12’s October meeting as a formal contribution.

  2. WB Loudness Ratings Confusion The use of WB LRs is causing confusion for designing, testing and manufacturing. Unresolved questions exist for WB LRs, scaling and relationship to narrow band ratings

  3. The Problems • With a same loudness level for both WB and NB systems the user experience of the WB system is significantly quieter than NB (more than 6 dB) • If the end-to-end WB and NB loudness levels are calculated from a same response level the difference is about 10 dB

  4. e.g. of LRs from a Same Response The LRs in the table below are calculated from the Nominal WB Send and Receive frequency response in the Annex of 810B

  5. TIA 810B Nominal Send Frequency Response

  6. TIA 810B Nominal Receive Frequency Response

  7. IEEE STIT Recommendation IEEE STIT recommends use the band# 1 to 20 loudness ratings in Table A.2 of Annex A of P.79 for wide-band applications in place of the “new” WB loudness ratings in Table G.1 of Annex G of P.79, 2001. This will likely be adopted by TIA TR 41.3.3 for the TIA 920-A digital WB standard This facilitates testing, and eliminates confusion with small compromise.

  8. Pros … • Avoids poor correlation between WB LRs with perceived loudness • Simplifies network loss planning considers mix of NB and WB conference connections • Less confusion improves confidence, broadens use of standard

  9. Cons … • The WB LR in Table G.1 has been issued for more than 5 years, it has been referenced by many • It still has slight perceivable end-to-end WB vs. NB loudness difference, NB can be about 2 dB louder than WB

  10. Comparison of Send Weighting Factors

  11. Comparison of Send Weighting Factors cont’d

  12. Comparison of Receive Weighting Factors

  13. Comparison of Receive Weighting Factors cont’d

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