ACOUSTICS IN SPORTS HALLSresearch on the acoustical behaviour of perforated panels                                        ...
ACOUSTICS IN SPORTS HALLS                                   Yvonne Wattez 1360809 graduation projectresearch on the acoust...
ACOUSTICS IN SPORTS HALLS                                   Yvonne Wattez 1360809 graduation projectresearch on the acoust...
ACOUSTICS IN SPORTS HALLS                                    Yvonne Wattez 1360809 graduation projectresearch on the acous...
seconds, the average reverberation time will be automatically less. E.L. Nesselaar used the standard for       her researc...
ACOUSTICS IN SPORTS HALLS                                                                      Yvonne Wattez 1360809 gradu...
ACOUSTICS IN SPORTS HALLS                                                              Yvonne Wattez 1360809 graduation pr...
ACOUSTICS IN SPORTS HALLS                                                     Yvonne Wattez 1360809 graduation projectrese...
– Norm: Tgem = 1,9 s; Tmax/fb = 2,7 s                                  EDT      T10     T20   T30      T15   normACOUSTICS...
ACOUSTICS IN SPORTS HALLS                                                                                                 ...
ACOUSTICS IN SPORTS HALLS                                   Yvonne Wattez 1360809 graduation project        research on th...
ACOUSTICS IN SPORTS HALLS                                                                 Yvonne Wattez 1360809 graduation...
ACOUSTICS IN SPORTS HALLS                                                      Yvonne Wattez 1360809 graduation projectres...
ACOUSTICS IN SPORTS HALLS                                                                   Yvonne Wattez 1360809 graduati...
ACOUSTICS IN SPORTS HALLS                                                                 Yvonne Wattez 1360809 graduation...
ACOUSTICS IN SPORTS HALLS                                       Yvonne Wattez 1360809 graduation projectresearch on the ac...
ACOUSTICS IN SPORTS HALLS                                                                                       Yvonne Wat...
ACOUSTICS IN SPORTS HALLS                                                                                        Yvonne Wa...
ACOUSTICS IN SPORTS HALLS                                                                                            Yvonn...
ACOUSTICS IN SPORTS HALLS                                                         Yvonne Wattez 1360809 graduation project...
ACOUSTICS IN SPORTS HALLS                                                     Yvonne Wattez 1360809 graduation projectrese...
Date                                                                                                                      ...
ACOUSTICS IN SPORTS HALLS                                   Yvonne Wattez 1360809 graduation projectresearch on the acoust...
2.5 ACOUSTICS IN SPORTS HALLS                                                                                             ...
ACOUSTICS IN SPORTS HALLS                                   Yvonne Wattez 1360809 graduation projectresearch on the acoust...
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P2 presentation Yvonne Wattez

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P2 presentation of Yvonne Wattez on Acoustics in sports halls. TU Delft, January 25th 2012.

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P2 presentation Yvonne Wattez

  1. 1. ACOUSTICS IN SPORTS HALLSresearch on the acoustical behaviour of perforated panels Presentation P2 25/01/2012 Graduation project of Yvonne Wattez Student nr. 1360809 Building Technology | Green Building Innovation Faculty of Architecture | TU Delft Mentor 1: Martin Tenpierik Mentor 2: Peter van Swieten
  2. 2. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Introduction1. Graduation so farProblem description- Legislation & standards- Parameters of acoustics in sports hallsReverberation time- Calculations vs. measurements- Porous materials vs. perforated panels- Possible explainations for the differencesSound absorption- Sound absorbing principles- Helmholtz resonator2. Graduation research- Standard measuremtents- Laboratory measurements- Scale model measurements3. Design4. Timeline 2
  3. 3. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012 Why? I like sports. I like acoustics. 3
  4. 4. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012 Problem description Complaints of PE teachers: - voice problems, (- hearing problems,) - tiredness. Mainly caused by bad acoustics of sports halls. Teachers need to shout to make themselves heard. Measurements show that the reverberation time is often too long. Pictures: Protest action in Rijssen - Holten. [source: tcturbantia 27 sept 2010] 4
  5. 5. seconds, the average reverberation time will be automatically less. E.L. Nesselaar used the standard for her research, not the recommendation. In this report the newest version of the standard of ISA-SportACOUSTICS IN SPORTS HALLS (NOC*NSF) will be used. Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012 Standard ISA-Sport 2005 Since 2005 the newest version of the standard: ‘Standards gymnastics and sports halls and parts of sports halls with educational use.’ is used in The Netherlands. This standard is also called: ISA-US1-BF1. The standard is still based on the reverberation time because a better option is not found yet. With the help and advice of some experts, the reverberation time is defined per volume of the hall. This is Legislation & important, because a sports hall twice the size should not have twice the reverberation time. The very big sports halls may have a very long reverberation time in that case. The acoustical quality is not linear with the volume. Besides the advise to introduce the volume in the standard for reverberation time, the Standards average absorption coefficient was advised to be at least 0,25. (Nijs 2004) Based on reverberation time [RT] The ISA-Sports standard includes: information on the location, the sports equipment, dressing rooms, and backgound noise level. and acoustics of the sports facility: • The average absorption coefficient [α] of the materials in the sports hall has to be at least 0,25. • The reverberation time depends on volume and absorbing behaviour of the room. The average Limits depend on size and volume. reverberation time in frequency band of 125-4000Hz may not be higher than 1,0 seconds for a [source: ISA Sport, ISA-N/A 1.1 ] sports hall of 14 x 22 x 5.5 m. • The reverberation time per frequency band (Tmax/fb) is calculated by Tav divided by Tmax/fb. This has to be ≥ 0,7. • The background noise level must not be higher than 40 dB(A). This applies to external sounds like outdoor traffic and internal sound sources like installation systems. • The noise insulation index between rooms for physical education and other residences/ classrooms should be 10 dB(A), preferably 15dB(A). Kind of room Size [m] (w x l x h) Reverberation time [s] A.1 Gymnastics ≤ 14 x 22 x 5.5 ≤ 1,0 A.2 Gym 13 x 22 x 7 ≤ 1,1 A.3 1/3 sports hall /gym 14 x 24 x 7 ≤ 1,2 B.1 Gym 16 x 28 x 7 ≤ 1,3 B.2 Gym 22 x 28 ≤ 1,4 B.3 2/3 sports hall 32 x 28 ≤ 1,5 C.1 Sports hall 24 x 44 ≤ 1,6 C.2 Sports hall 28 x 48 x 7 ≤ 1,7 C.3 Sports hall 28 x 48 x 9 ≤ 1,9 D.1 Sports hall 28 x 88 x 7 ≤ 2,0 picture: sports hall in Amstelveen D.2 Sports hall 35 x 80 x 10 ≤ 2,3 [source:www.sportbedrijfamstelveen.nl] 5 Conclusion
  6. 6. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Reverberation Time ParametersThe reverberation time is defined as the time that expires before a sound pressure Reverberation Time (RT):has decayed by 60 dB after the sound source has been swiched off. Sabine’s formulaT15 (blue), T20, T30 (black) Sabine 1 V 1 VRT= ⋅ RT = 6A 6 A + 4mV with: RT= reverberation time [s] V= volume of room [m3] A= total absorption of materials in room =  (α S ) i i with: αi = absorption coefficient of element i [-] Si = surface of element i [m2] 4mV = correction for air attenuation Sabine correction of Lau Nijs This correction is made because Sabine is based on a cube. Sports halls shape. By replacing the surface factor S by a certain part of the volume realistic. 1 V RT = 6 α ⋅ 6V 2/3 with: RT= reverberation time [s] V= volume of room [m3] α = average absorption coefficient Eyring_1 This formula of Eyring works with the mean value of all absorption coe 1 V RT = 6 S ⋅ ln (1 − α )−1  6  
  7. 7. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Absorption coefficient ParametersAbsorption coefficient a is a measure of the efficiency of a surface or material in Waabsorbing sound. α= WiReflected sound (A, B, C) rTransmitted sound (D) t absorption coefficient a=Absorbed sound (E, F, G, H, I, J, K) a absorbed energy/incident energy r+t+a = 1 Sports hall: a= 1-r SRC diagram: Everest 2001 7
  8. 8. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Speech Intelligibility ParametersDepends on:- background noise- reverberation time- shape of the roomParameters to measure speech intelligibility:- Speech Transmission Index STI- RApid Speech Transmission Index RASTI(mostly used in Europe)Based on a comparison of the outgoing and incoming sound.Between 0 and 1.0.8 or higher is excellent, 0.3 is the lower limit to understand sentences. 8
  9. 9. – Norm: Tgem = 1,9 s; Tmax/fb = 2,7 s EDT T10 T20 T30 T15 normACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Flutter echo Parameters De nagalmtijd als te berekenen parameter in between Reflecting sound in het ontwerp parallel walls. 90 m = 2 x zaallengte Sportzaal (32x24x7,8 m) – Norm: Tgem = 1,5 s; Tmax/fb = 2,1 s 3 [source: Vugts, J. (2008) LBP|SIGHT via nvbv.org] [source: www.ecophon.nl] 9
  10. 10. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Formulas compared: Reverberation TimeBig differences found in comparison of different formulas,computer programmes and measurements.Schijndel Calculations vs. measurements. Method frequency average 500Hz 2000Hz Standard ISA Sport 1.6 1.6 1.6 Standard ISA Sport max 2.3 2.3 2.3 L.Nijs & Sabine 2.22 1.62 2.24 Sabine 1.84 1.34 1.85 Eyring 1.62 1.09 1.62 Fitzroy 1.64 1.36 1.63 ODEON T30 1.79 1.83 1.66 CATT ACOUSTIC T15 1.77 1.86 1.64 CATT ACOUSTIC T30 2.01 2.2 1.77 Measurement T20 2.14 2.64 1.82 RT: methods vs. measurement Schijndel 3 2.5 L.Nijs & Sabine Sabine Reverberation Time [s] 2 Eyring Fitzroy 1.5 ODEON T30 1 CATT ACOUSTIC T15 CATT ACOUSTIC T30 0.5 Measurement T20 Standard ISA Sport 0 Standard ISA Sport max average 500Hz 2000Hz Frequency [Hz] sports hall Schijndel: perforated steel panels on walls 10
  11. 11. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation project research on the acoustical behaviour of perforated panels P2 presentation 25/01/2012 Different halls D1 T20 Sporthal compared: Reverberation Time 4.0 Porous materials vs. perforated steel panels. The reverberation is much shorter 3.0 than expected at low frequencies in a sports hall constructed with perforated panels. The perforated panels seem toT [s] 2.0 behave differently than expected from laboratory results. (Especially at low frequencies.) 1.0 0.0 125 250 500 1000 2000 4000 f [Hz] S1 S2 S3 AVERAGE Expected and measured RT; porous materials SRC: LBP|SIGHT 11
  12. 12. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012So, the panels seem to behave differently in practice than in a laboratory situation.Goal of this research:Determine why a difference in sound absorption behaviour ofperforated steel panels exists between practical applications and lab situations. Next, some theory... 12
  13. 13. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Sound absorbing principles- Friction and airflow resistance through a material. Porous materials (Air)- Resonance Plate resonator Helmholtz resonator: perforated panels friction porous materials sound absorption plate resonators resonance Helmholtz resonators perforated panel 13
  14. 14. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Plate resonatorsA mass-spring system exists of a specific oscillation value. When the mass starts moving,it will start oscillating in a specific speed; the resonant frequency.The absorption coefficient can be calculated with the use of acoustical impedance. 14
  15. 15. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Acoustical impedance p (t )Acoustical impedance is the ratio of the sound pressure at a boundary surface to the sound Za =flux (flow velocity of the particles or volume velocity, times area) through the surface. v(t ) ⋅ SSpecific acoustical impedance is the ratio of the sound pressure at a point to the sound flux p (t )through that point. Zs = v(t ) 15
  16. 16. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Helmholtz resonators, perforated panel Z 1 Z1 = ZR/hAbsorption coefficient total ZR = ZM/ZV 4 Z1 Z 0 ZVα= ( Z + Z 0 ) 2 + Z12 ZMFor Helmholtz resonators can be calculated from: Z 0 airZ0= the characteristic impedance of airZ1= the impedance of the resonator in total = ZR/h ZR= ZV+ZM h h= the percentage perforations ZV = impedance of the air cavity ZM = impedance of the air in the perforationZ’ =Z’M+ Z’V = the real component of the complex number of ZRZ1’’ =Z’’M+ Z’’V = the imaginary component of the complexnumber of ZRZ= impedance, a complex number (z)Z’= the real component of the impedance (a)Z’’= the imaginary component of the impedance (i*b)z= a+i*b or Z=Z’+Z’’ 16
  17. 17. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012 83Helmholtz resonators, important factorsPercentage perforation The more perforations, the higher the resonance frequency.Thickness of facing The thicker, the higher the frequency of the maximal absorption peak. Fig,2. Absorption coefficient versus frequency graphs Fig,3. Absorption coefficient versus frequency graphs for for a perforated faced sound absorber system for different a perforated faced sound absorber system using different percentage perforations of the facing. (Davern 1977) thickness of facing with the same percentage perforations. (Davern 1977) 17
  18. 18. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Helmholtz resonators, important factors 85Density of the porous backing material The denser, the broader the tuning of the system.Air space between the facing and backingmaterial Gives an overall decrease of absorbing properties of the system. Fig,4. Absorption coefficient versus frequency graphs for Fig,5. Absorption coefficient versus frequency graphs for a perforated faced sound absorber system using porous a perforated faced sound absorber system with and without backing materials of different densities. (Davern 1977) an air space between facing and porous backing with the same facing perforations but different facing thickness. (Davern 1977) 18
  19. 19. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Helmholtz resonators, important factors 87Impervious layer between the facing andbacking material Gives a huge overall decrease of absorbing properties of the system. Fig,6. Absorption coefficient versus frequency graphs for Fig,7. As in figure 13. but with different facing perforations a perforated faced sound absorber system with and without and the same facing thickness. (Davern 1977) an impervious layer between facing and porous backing with the same facing perforations but different facing thickness. (Davern 1977) 19
  20. 20. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Fundamental data: standard measurements in sports halls: RT andbackground noise. Research to doTesting hypothese:A perforated steel panel behaves differently in practice than in a laboratory Test method: scale modelsituation on absorption coefficient because the shape of the panels causes S Ra better sound absorption of parallel striking sound than on sound with anormal incidence, based on a phase shift principle. This principle increases S Rthe absorption coefficient results of the measurement in practice since thereis more specific parallel striking sound than in a reverberation room (like the S Rlaboratory).A perforated steel panel behaves differently in practice than in a laboratory Test method: laboratorysituation on absorption coefficient because the different placement of the measurementpanel in the laboratory than in practice has influence on the result. a b 20
  21. 21. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012Results and design: Research to doWhen the shape of the panels and so the phase shift seems to have goodinfluence on the sound absorbing behaviour, the design could adapt on thisresult by using panels with other dimensions.When the height / different placement of the panels in the laboratory gives Test method: scale modeldifferent sound absorbing results, the design of the backing constructioncould be adapted in a way that the sound absorbing behaviour is optimized. S R S R S R Test method: laboratory measurement a b 21
  22. 22. Date Week Friday Acvity Tuesday Monday Deadline Thursday Weekend Wednesday Presentaons Literature, theory 12-Dec 50 Thursday: Zalen bekend (materiaal bekend) fabrikant benaderen Literature, theory, organize material 19-Dec 51 Timeline: Literature, theory 26-Dec 52 geen onderwijs Second mentor known 02-Jan 1 Prepare tests, prepare P2 09-Jan 2 Timeline version 19-01-2012 Prepare tests, prepare P2 16-Dec 3 P2 Prepare tests, prepare P2 23-Dec 4 afwezig Report (not a lot) 30-Jan 5 Tests scale model 06-Feb 6 Marterial available Tests scale model 13-Feb 7 Tests sports halls done Tests scale model 20-Feb 8 ACOUSTICS IN SPORTS HALLS Tests sports hall 27-Feb 9 research on the acoustical behaviour of perforated panels P3 Tests sports hall 05-Mar 10 Tests laboratory 12-Mar 11 aanvraag P4 Tests laboratory done Tests laboratory 19-Mar 12 Tests laboratory 26-Mar 13 Report 02-Apr 14 In situ measurements done Report 09-Apr 15 Design 16-Apr 16 Design 23-Apr 17 Design, Presentaon 18 P4 Presentaon 30-Apr 07-May 19 Presentaon 14-May 20 Presentaon 21-May 21 aanvraag P5 Most conclusions finished 28-May 22 Report 04-Jun 23 Report 11-Jun 24 Report, Prepare presentaon 18-Jun 25 Prepare presentaon 25-Jun 26 P2 presentation 25/01/2012 Yvonne Wattez 1360809 graduation project P522 02-Jul Prepare presentaon 27
  23. 23. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012 Questions? 23
  24. 24. 2.5 ACOUSTICS IN SPORTS HALLS 2.0 Yvonne Wattez 1360809 graduation project research on the acoustical behaviour of perforated panels P2 presentation 25/01/2012 1.5 RT [s] 1.0 0.5 Example RT to a Nagalmtijd 0.0 125 250 500 1000 Gymzaal (21 x 12 x 6 m) f [Hz] Meting vs berek ening Gymzaal (21x12x6 m) T20-meting T-Sabine – Norm: Tgem = 1,0 s; Tmax/fb = 1,4 s 2.5 2.0 Tgem = 1,6 s 1.5 RT [s] Tgem = 1,0 s 1.0 0.5 Tgem = 0,8 s 0.0 125 250 500 1000 2000 4000 f [Hz] T20-meting T-Sabine norm ‘Berekende’ geluidabsorptiecoëfficiënt De nagalmtijd in relatie tot de v Gymzaal (21 x 12 x 6 m) van de geluidabsorptie Meting vs berek ening Sporthal (48x28x9 m) 0.6 α ‘aanwezig’ - Norm: Tgem = 1,9 s; Tmax/fb = 2,7 s 0.5 0.4 α ‘norm’ α [-] 0.3 0.2 α ‘gemeten’De nagalmtijd in relatie tot de verdeling 0.1van de geluidabsorptie 0.0 125 250 500 1000 2000 4000 3 varianten met gelijke hoeveelheid geluidabsorptieSporthal (48x28x9 m) f [Hz] • Variant 1: Wandabsorptie rondom bovenste vlakken • Variant 2: Wandabsorptie rondom onderste vlakken- Norm: Tgem = 1,9 s; Tmax/fb = 2,7 s T20-meting T-Sabine norm • Variant 3: Wandabsorptie twee hele wanden 24
  25. 25. ACOUSTICS IN SPORTS HALLS Yvonne Wattez 1360809 graduation projectresearch on the acoustical behaviour of perforated panels P2 presentation 25/01/2012absorption coefficient calculation porousmaterialsZs,material= specific impedance of the material Z 1 Z1 = ZR/h total ZR = ZM/ZV α= 1− (1 − Z / Z 0 s , material ) ZV (1 + Z / Z ) 2 ZM 0 s , material Z 0 air h 25
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