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The Song of Glasses: A Study of Harmony in Acoustical Criteria

Explore the harmony of glasses through acoustical criteria, sound analysis, and subjective approaches. Discuss the strike note, timbre, consonance, and dissonance in glass sound. Test listening experiences and analyze the harmonic and inharmonic partials using string instruments and cylindrical pipes. Discover the impact of shape, materials, and manufacturing on glass sound quality. Conclude with insights on pitch, timbre, time decay, and new glass design possibilities.

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The Song of Glasses: A Study of Harmony in Acoustical Criteria

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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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