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Past, Present and Future of STI Herman J. M. Steeneken (www.steeneken.com)

Past, Present and Future of STI Herman J. M. Steeneken (www.steeneken.com).

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Past, Present and Future of STI Herman J. M. Steeneken (www.steeneken.com)

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  1. Past, Present and Future of STI Herman J. M. Steeneken (www.steeneken.com) Ecophon Seminar, Sept. 2006

  2. Past: STI (1971, 1980), Envelope Spectrum (1972), MTF (1975), RASTI (1979), prediction by ray-tracing(1981), IEC 60268-16 (1988, 1998)Present: Revised STI (1992, 1999, 2002), STIPA (2001), IEC 60268-16 (2003), ISO 9921 (2003)New and Future: Binaural STI, improvement measurement STI from speech signal, non-native speech, vocoders Ecophon Seminar, Sept. 2006

  3. Signal-to-Noise ratio !!! Ecophon Seminar, Sept. 2006

  4. Assessment Methods • Subjective assessment with subjects (speakers and listeners): representative, limited reproduction, no diagnostics, laborious • Objective assessment based on physical properties (measurements): reproducible, diagnostic, fast • Objective methods allow prediction of system performance: design tool Ecophon Seminar, Sept. 2006

  5. Speech and Noise Ecophon Seminar, Sept. 2006

  6. Speech envelope function and envelope spectrum Ecophon Seminar, Sept. 2006

  7. Spatial line frequency equivalent to MTF Ecophon Seminar, Sept. 2006

  8. Distortion of Speech Envelope Ecophon Seminar, Sept. 2006

  9. Dynamic measurement of SNR Ecophon Seminar, Sept. 2006

  10. Matrix for seven MTF’s 1 Hz 3 Hz 10 Hz X Ecophon Seminar, Sept. 2006

  11. CALCULATION of STI Ecophon Seminar, Sept. 2006

  12. Calculation scheme Ecophon Seminar, Sept. 2006

  13. Frequency weightings (various studies) Ecophon Seminar, Sept. 2006

  14. Redundancy with image detection Ecophon Seminar, Sept. 2006

  15. Frequency weightings (CVC words) Ecophon Seminar, Sept. 2006

  16. Relation Noise and Band-pass limiting S.d.= 4.4% Male speech Ecophon Seminar, Sept. 2006

  17. Listening test with four subjects Ecophon Seminar, Sept. 2006

  18. Embedded CVC words: versta des over en nu fijs uit het woord zek einde noteer lal punt “Semi random” combination of: 17 initial consonants 15 vowels 11 final consonants Ecophon Seminar, Sept. 2006

  19. Relation AGC and echoes S.d.= 6.9 % Male speech Ecophon Seminar, Sept. 2006

  20. Qualification of STI (Acustica, 1984) Ecophon Seminar, Sept. 2006

  21. Performance cabin public address Ecophon Seminar, Sept. 2006

  22. Iso-STI contours Ecophon Seminar, Sept. 2006

  23. Effective gain of a PA-system Ecophon Seminar, Sept. 2006

  24. Field measurement Ecophon Seminar, Sept. 2006

  25. Full STI (STI-14 and limited modulation frequency range STI-3) • STI-14 • Seven octave bands • 14 Modulation frequencies • Random envelope for octaves • not under test • STI-3 • Seven octaves • 3 Modulation frequencies • (1.0, 3.15, and 10 Hz) • Random envelope for octaves • not under test Ecophon Seminar, Sept. 2006

  26. RASTI (Room Acoustics STI,1979) Only for person-to-person communication assessment Two octave bands (500Hz and 2 kHz) Complex envelope (4 and 5 mod. freq.) see Acustica 1984, IEC 60268-16 Ecophon Seminar, Sept. 2006

  27. STI-PA (STI Public Address, 2001) Assessment of Public Address including: acoustic environment, band-pass limiting, overload dis- tortion Seven octave bands (125 Hz and 250 Hz merged) Complex envelope (2 simultaneous modulation frequencies per band) see IEC 60268-16 Ecophon Seminar, Sept. 2006

  28. Future • Binaural STI • Improvement using Speech as test signal • Non-native talkers and listeners Ecophon Seminar, Sept. 2006

  29. Future: Binaural STI (I) Use artificial head and perform simultaneous measurement on both ears Select highest performance (best ear selection) Use cross correlation approach for 500, 1000, and 2000 Hz. Ecophon Seminar, Sept. 2006

  30. Future: Binaural STI (II) Ecophon Seminar, Sept. 2006

  31. Future: improvement Speech Signal as test signal Ecophon Seminar, Sept. 2006

  32. Future: non-native talkers and listeners Ecophon Seminar, Sept. 2006

  33. Conclusions • STI predicts the speech intelligibility for many types of distortion: noise, band-pass limiting, non-linearity's, temporal, vocoding, non-native speech, and binaural hearing. • Improvements (measuring methods or scope) of STI will not change the qualification ranges. • STI is an international standardized method (ISO9921, IEC 60268-16) and used for many national standards. Ecophon Seminar, Sept. 2006

  34. Questions? Ecophon Seminar, Sept. 2006

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