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THE SONG OF GLASSES

THE SONG OF GLASSES. LAIN - UMR CNRS 5011 Univ. Montpellier 2 - cc 82 34095 MONTPELLIER cedex 5 FRANCE. Ing. Jean-Yves Ferrandis Pr. Gerard Leveque Pr. Jacques Attal. GOAL: STUDY OF THE HARMONY OF GLASSES  Acoustical criteria  the strike note : pitch and sound decay  timbre

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THE SONG OF GLASSES

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  1. THE SONG OF GLASSES LAIN - UMR CNRS 5011 Univ. Montpellier 2 - cc 82 34095 MONTPELLIER cedex 5 FRANCE Ing. Jean-Yves Ferrandis Pr. Gerard Leveque Pr. Jacques Attal

  2. GOAL: STUDY OF THE HARMONY OF GLASSES Acoustical criteria  the strike note : pitch and sound decay  timbre  consonance and dissonance Subjective approach

  3. I. Sound analysis : theoretical background • II. Experiences on glasses and crystal glasses • III. Discussion • IV. Test of listening • V. Conclusions FRAME WORK

  4. Harmonic partials : string instruments • Inharmonic partials : infinite cylindrical pipes • Spectral analysis • Circular plates • Vibration of bells • Consonance intervals I. Sound analysis : theoreticalbackgrond

  5. Harmonic partials : string instruments z • String equation Solutions T T x r density S cross-area T strain force n order of the mode frequency n = 1, 2, 3, 4 ….

  6. Inharmonic partials : infinite cylindrical pipes • Infinite cylindrical pipes z : axis of the pipe q : angle in the shear cut e : thickness of the pipe e, n : Young modulus, Poisson coefficient R : radius of the pipe r : density The partial mode are not harmonic frequency intervals [1, 8/3, 5, 8, 35/3 …]

  7. Spectral analysis Cylinders 8 1 2 3 4 5 6 7 Fondamental frequency m=2 m=3 m=4 m=5 String vibrations m = 2 m = 1 8/3

  8. Circular plates • Chladni ’s law (empirical relation ship) where c is the sound velocity (n,m) is the mode numbers • for flat plates p = 2 • for non flat plates (cymbals, bells) p < 2

  9. Vibration of bells • The bells can be tuned on harmonic partials

  10. Consonance intervals for bells

  11. Pitch • Sound decay • Warble II. Experiences on glasses and crystal glasses

  12. Sound analysis : Typical response

  13. Sound decay t :Time constant for a decay  0.368

  14. Warble A B B A A B B Beats due to a dissimetry of the sample Tea cup

  15. Shape • Materials • Manufacturing III. Discussion : Effects of

  16. Shape dependance ELLIPTICAL CONICAL f2/f1 = 2.35 (tenth = 2.4 ) can be adjusted from 2 to 2.5 according to ellipticity f2/f1 = 1.48 f3/f1 = 2.01 (quint = 1.5) can be adjusted with the opening angle • The thicker the glass the higher the pitch

  17. Materials dependance Verre blanc Cristal • The time constant of the decay is four times as large for the crystal glass with same shape. • The pitch and the timbre are correctly appreciated when the decay is small.

  18. Manufacturing Repeatability on a serial of identical glasses Spreading of the measurements (fundamental and first harmonic)

  19. Test procedure • Collect opinion from an audience of 25 people • Listening to synthetic sounds which simulates glass strikes : effect of pitch, timbre, time decay ... • Note : This test has been performed on non informed audience, but is dependant on the musical background of each one IV.Testof listeing

  20. Q : PITCH EFFECT : thickness and shapeA1 B1 A : Preference for bass tones Q : TIME DECAYA2 B2 A : Large agreement for long decay : crystal glass is unanimously appreciated Q : RATIO f2/f1A4 B4 B5 B6 A : Audience can make difference between consonance and dissonance but does not agree on the appreciation Q : NUMBER OF PARTIALSA7 B7 A : Slight preference for few partials V. Test and results

  21. Conclusions • PSYCHOLOGICAL IMPACT OF THE SONG OF THE GLASS • PITCH • TIMBRE • TIME DECAY • MANUFACTURING QUALITY CONTROL • NEW DESIGN OF GLASS CONSONANT SERIALS NEW SHAPES WHICH ENHANCE SPECIFIC MODES

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