I-Acoustics
Module 01 Basic theory & Reverberation time .........................................................................................1
1. Basic theory ...................................................................................................................................................1
1.1. What is sound? .................................................................................................................................................................1
1.2. Wavelength and frequency ...............................................................................................................................................3
1.3. Octave and third octave bands .........................................................................................................................................5
2. Sound pressure ..............................................................................................................................................8
2.1. Decibel [dB] ......................................................................................................................................................................8
2.2. Sound pressure (P) and sound pressure level (Lp) ..........................................................................................................12
2.3. Adding sound levels ........................................................................................................................................................17
2.4. Equal loudness level contours.........................................................................................................................................24
2.5. Weighted sound levels ....................................................................................................................................................26
2.6. Psychoacoustics ..............................................................................................................................................................26
3. Disturbing noise ...........................................................................................................................................27
3.1. Noise Rating (ISO R 1996) ...............................................................................................................................................27
3.2. Equivalent Continuous Sound Level ................................................................................................................................27
3.3. Statistical Noise Levels ....................................................................................................................................................28
4. Types of sound waves ..................................................................................................................................29
4.1. Point source: spherical sound waves ..............................................................................................................................29
4.2. Plane source: plane sound waves ...................................................................................................................................29
4.3. Line source: cylindrical sound waves ..............................................................................................................................29
4.4. Plane, line and point sources ..........................................................................................................................................30
4.5. SPL and distance to the source .......................................................................................................................................30
5. Nature of the sound .....................................................................................................................................30
5.1. Fourier transformation ...................................................................................................................................................31
5.2. Doppler effect .................................................................................................................................................................31
5.3. Sonic boom (sound barrier) ............................................................................................................................................32
5.4. Directivity ........................................................................................................................................................................32
5.5. Localization of sound ......................................................................................................................................................34
6. Reverberation time ......................................................................................................................................34
6.1. Cocktail party effect vs. Lombard effect..........................................................................................................................35
6.2. Which factors influence the acoustical quality of a room? .............................................................................................35
6.3. Propagation of sound......................................................................................................................................................37
6.4. Direct sound and early reflections ..................................................................................................................................37
6.5. Shape of the room and materials ...................................................................................................................................38
7. Reverberation ..............................................................................................................................................39
7.1. Flutter echo .....................................................................................................................................................................40
7.2. Reverberation time .........................................................................................................................................................42
7.3. Measurement of reverberation time ..............................................................................................................................47
Module 02 Sound Absorption .................................................................................................................52
1. Introduction .................................................................................................................................................52
2. Measurement principles ..............................................................................................................................53
2.1. Reverberation room method ..........................................................................................................................................53
2.2. Impedance tube method ................................................................................................................................................55
3. Classification of sound absorbing system......................................................................................................59
3.1. Principle of sound absorption .........................................................................................................................................60
3.2. Porous absorbers ............................................................................................................................................................60
3.3. Helmholtz resonators .....................................................................................................................................................67
3.4. Panel absorber ................................................................................................................................................................71
3.5. People and furniture .......................................................................................................................................................72
, 4. Other absorbing surfaces .............................................................................................................................73
5. Conclusions ..................................................................................................................................................74
Module 03 Concert Hall acoustics ...........................................................................................................76
1. Introduction .................................................................................................................................................76
2. Architectural criteria ....................................................................................................................................77
2.1. Most important architectural criteria .............................................................................................................................77
3. Acoustical criteria.........................................................................................................................................86
3.1. Overview .........................................................................................................................................................................86
3.2. Correlation with reverberation time? .............................................................................................................................89
3.3. Summary .........................................................................................................................................................................89
3.4. Measurement example ...................................................................................................................................................90
4. Diffusers & variable acoustics .......................................................................................................................90
4.1. Diffusers ..........................................................................................................................................................................90
4.2. Variable acoustics ...........................................................................................................................................................93
5. Some examples of concert halls ...................................................................................................................94
5.1. Acoustics defects ............................................................................................................................................................94
5.2. Evaluation of concert hall acoustics ................................................................................................................................96
5.3. Stage terminology ...........................................................................................................................................................98
5.4. Best concert halls ............................................................................................................................................................99
6. Acoustical studies .......................................................................................................................................102
6.1. Examples .......................................................................................................................................................................103
7. Case study including variable acoustics & acoustic modelling .....................................................................105
8. Some Belgian concert halls .........................................................................................................................112
Module 04 Airborne Sound insulation ..................................................................................................115
1. Introduction to Building Acoustics ..............................................................................................................115
1.1. Sound insulation, a necessity? ......................................................................................................................................115
1.2. Standardisation .............................................................................................................................................................116
1.3. General contemplations ...............................................................................................................................................116
1.4. Why airborne sound insulation? ...................................................................................................................................116
2. Transfer of sound in buildings .....................................................................................................................117
2.1. Airborne vs. Structure borne sounds ............................................................................................................................117
3. Airborne sound insulation of building elements .........................................................................................119
3.1. Measurement of the sound reduction index R .............................................................................................................120
3.2. Acoustical laboratory ....................................................................................................................................................122
3.3. Acoustical standards for sound insulation ....................................................................................................................122
3.4. Conversion of R ➔ Rw...................................................................................................................................................123
3.5. Spectrum adaptation terms C and Ctr ..........................................................................................................................123
3.6. How to measure STC? ...................................................................................................................................................127
3.7. Subjective resulting effect of Rw...................................................................................................................................130
3.8. Weighted sound reduction index of a composite building element .............................................................................130
4. Airborne sound insulation of building constructions ...................................................................................131
4.1. Apparent sound reduction R’ ........................................................................................................................................131
4.2. Weighted apparent sound reduction index R’w ...........................................................................................................131
4.3. Increasing the equivalent absorption area? .................................................................................................................131
4.4. Weighted standardized level difference DnT,w .............................................................................................................132
5. prNBN S01-400-1 (2019): Acoustical criteria for dwellings ..........................................................................132
5.1. Old standards ................................................................................................................................................................132
5.2. Updated Belgian standards ...........................................................................................................................................133
5.3. New European descriptors............................................................................................................................................133
5.4. Acoustical criteria for dwellings (prNBN S 01-400-1:2019) ..........................................................................................135
, 6. Airborne sound insulation of single leaf walls .............................................................................................141
6.1. Transmission of airborne sound through a homogeneous single leaf wall ...................................................................141
7. Airborne sound insulation of double leaf walls ...........................................................................................144
7.1. Design of double leaf constructions: ............................................................................................................................146
7.2. Gyproc plasterboard walls ............................................................................................................................................147
7.3. Timber frame walls .......................................................................................................................................................150
8. Building guidelines .....................................................................................................................................152
8.1. Anchorless cavity wall ...................................................................................................................................................152
8.2. Detailing ........................................................................................................................................................................153
8.3. GypBox-system..............................................................................................................................................................153
8.4. Example of a layout.......................................................................................................................................................155
8.5. Conclusion ....................................................................................................................................................................155
Module 05a Structure borne sound insulation ......................................................................................155
1. Introduction ...............................................................................................................................................155
1.1. Measurement principle ..................................................................................................................................................155
2. Impact sound insulation: Demands from Belgian standard NBN S01-400-1 .................................................157
2.1. Acoustical criteria for dwellings NBN S 01-400-1:2008 & prNBN S 01-400-1:2019 .....................................................157
2.2. Direct hit in contact with the structure ........................................................................................................................161
2.3. Improvement of the structure borne sound transmission in dwellings: intervention at the source: mass-spring systems
(Floating screed) ...........................................................................................................................................................164
2.4. Working principle mass-spring system .........................................................................................................................167
2.5. Determination of the structure borne sound insulation in laboratory conditions .......................................................169
3. Calculations................................................................................................................................................170
3.1. Predictive calculations according to EN 12354-2 ..........................................................................................................170
4. Guidelines ..................................................................................................................................................177
5. Case study ..................................................................................................................................................180
5.1. Case study 1 ..................................................................................................................................................................180
5.2. Case study 2 ..................................................................................................................................................................183
5.3. Case study 3 ..................................................................................................................................................................185
5.4. Stairs & platforms .........................................................................................................................................................185
6. Wooden floors ...........................................................................................................................................186
6.1. Timber frame floors ......................................................................................................................................................186
6.2. CLT floors: cross laminated timber ................................................................................................................................188
6.3. How to reach class A? ...................................................................................................................................................191
7. Conclusions ................................................................................................................................................191
Module 05b Service equipment noise ...................................................................................................192
1. Demands for service equipment noise in dwellings ....................................................................................192
1.1. Acoustical criteria for dwellings NBN S 01-400-1: 2008 ................................................................................................192
1.2. Acoustical criteria for dwellings prNBN S 01-400-1:2019 .............................................................................................196
2. Calculation .................................................................................................................................................198
3. Building guidelines .....................................................................................................................................198
3.1. Limiting service equipment noise in dwellings .............................................................................................................199
3.2. Often appearing complaints … ......................................................................................................................................200
3.3. Other possible equipment noise...................................................................................................................................210
Module 06 Human hearing & Noise on the workplace ..........................................................................211
1. Introduction ...............................................................................................................................................211
1.1. Motivation ....................................................................................................................................................................211
2. Human hearing: Working principle .............................................................................................................213
2.1. Introduction ..................................................................................................................................................................213
2.2. The middle ear ..............................................................................................................................................................214
, 2.3. The inner ear.................................................................................................................................................................215
3. Human hearing: Pathology – what can go wrong? ......................................................................................218
3.1. How can we test it? ......................................................................................................................................................218
3.2. Audiograms ...................................................................................................................................................................219
3.3. Hearing loss ? ................................................................................................................................................................220
3.4. Reality check .................................................................................................................................................................221
3.5. When can you expect hearing loss?..............................................................................................................................221
3.6. Tinniwhatus? ................................................................................................................................................................222
3.7. Tips................................................................................................................................................................................223
4. Human hearing: (individual) hearing protection .........................................................................................223
4.1. Hearing protection ........................................................................................................................................................223
5. Legislation concerning noise on the workplace ...........................................................................................228
5.1. Noise emission by equipment used outdoors ..............................................................................................................228
5.2. Noise on the workplace ................................................................................................................................................230
Module 01 Basic theory & Reverberation time .........................................................................................1
1. Basic theory ...................................................................................................................................................1
1.1. What is sound? .................................................................................................................................................................1
1.2. Wavelength and frequency ...............................................................................................................................................3
1.3. Octave and third octave bands .........................................................................................................................................5
2. Sound pressure ..............................................................................................................................................8
2.1. Decibel [dB] ......................................................................................................................................................................8
2.2. Sound pressure (P) and sound pressure level (Lp) ..........................................................................................................12
2.3. Adding sound levels ........................................................................................................................................................17
2.4. Equal loudness level contours.........................................................................................................................................24
2.5. Weighted sound levels ....................................................................................................................................................26
2.6. Psychoacoustics ..............................................................................................................................................................26
3. Disturbing noise ...........................................................................................................................................27
3.1. Noise Rating (ISO R 1996) ...............................................................................................................................................27
3.2. Equivalent Continuous Sound Level ................................................................................................................................27
3.3. Statistical Noise Levels ....................................................................................................................................................28
4. Types of sound waves ..................................................................................................................................29
4.1. Point source: spherical sound waves ..............................................................................................................................29
4.2. Plane source: plane sound waves ...................................................................................................................................29
4.3. Line source: cylindrical sound waves ..............................................................................................................................29
4.4. Plane, line and point sources ..........................................................................................................................................30
4.5. SPL and distance to the source .......................................................................................................................................30
5. Nature of the sound .....................................................................................................................................30
5.1. Fourier transformation ...................................................................................................................................................31
5.2. Doppler effect .................................................................................................................................................................31
5.3. Sonic boom (sound barrier) ............................................................................................................................................32
5.4. Directivity ........................................................................................................................................................................32
5.5. Localization of sound ......................................................................................................................................................34
6. Reverberation time ......................................................................................................................................34
6.1. Cocktail party effect vs. Lombard effect..........................................................................................................................35
6.2. Which factors influence the acoustical quality of a room? .............................................................................................35
6.3. Propagation of sound......................................................................................................................................................37
6.4. Direct sound and early reflections ..................................................................................................................................37
6.5. Shape of the room and materials ...................................................................................................................................38
7. Reverberation ..............................................................................................................................................39
7.1. Flutter echo .....................................................................................................................................................................40
7.2. Reverberation time .........................................................................................................................................................42
7.3. Measurement of reverberation time ..............................................................................................................................47
Module 02 Sound Absorption .................................................................................................................52
1. Introduction .................................................................................................................................................52
2. Measurement principles ..............................................................................................................................53
2.1. Reverberation room method ..........................................................................................................................................53
2.2. Impedance tube method ................................................................................................................................................55
3. Classification of sound absorbing system......................................................................................................59
3.1. Principle of sound absorption .........................................................................................................................................60
3.2. Porous absorbers ............................................................................................................................................................60
3.3. Helmholtz resonators .....................................................................................................................................................67
3.4. Panel absorber ................................................................................................................................................................71
3.5. People and furniture .......................................................................................................................................................72
, 4. Other absorbing surfaces .............................................................................................................................73
5. Conclusions ..................................................................................................................................................74
Module 03 Concert Hall acoustics ...........................................................................................................76
1. Introduction .................................................................................................................................................76
2. Architectural criteria ....................................................................................................................................77
2.1. Most important architectural criteria .............................................................................................................................77
3. Acoustical criteria.........................................................................................................................................86
3.1. Overview .........................................................................................................................................................................86
3.2. Correlation with reverberation time? .............................................................................................................................89
3.3. Summary .........................................................................................................................................................................89
3.4. Measurement example ...................................................................................................................................................90
4. Diffusers & variable acoustics .......................................................................................................................90
4.1. Diffusers ..........................................................................................................................................................................90
4.2. Variable acoustics ...........................................................................................................................................................93
5. Some examples of concert halls ...................................................................................................................94
5.1. Acoustics defects ............................................................................................................................................................94
5.2. Evaluation of concert hall acoustics ................................................................................................................................96
5.3. Stage terminology ...........................................................................................................................................................98
5.4. Best concert halls ............................................................................................................................................................99
6. Acoustical studies .......................................................................................................................................102
6.1. Examples .......................................................................................................................................................................103
7. Case study including variable acoustics & acoustic modelling .....................................................................105
8. Some Belgian concert halls .........................................................................................................................112
Module 04 Airborne Sound insulation ..................................................................................................115
1. Introduction to Building Acoustics ..............................................................................................................115
1.1. Sound insulation, a necessity? ......................................................................................................................................115
1.2. Standardisation .............................................................................................................................................................116
1.3. General contemplations ...............................................................................................................................................116
1.4. Why airborne sound insulation? ...................................................................................................................................116
2. Transfer of sound in buildings .....................................................................................................................117
2.1. Airborne vs. Structure borne sounds ............................................................................................................................117
3. Airborne sound insulation of building elements .........................................................................................119
3.1. Measurement of the sound reduction index R .............................................................................................................120
3.2. Acoustical laboratory ....................................................................................................................................................122
3.3. Acoustical standards for sound insulation ....................................................................................................................122
3.4. Conversion of R ➔ Rw...................................................................................................................................................123
3.5. Spectrum adaptation terms C and Ctr ..........................................................................................................................123
3.6. How to measure STC? ...................................................................................................................................................127
3.7. Subjective resulting effect of Rw...................................................................................................................................130
3.8. Weighted sound reduction index of a composite building element .............................................................................130
4. Airborne sound insulation of building constructions ...................................................................................131
4.1. Apparent sound reduction R’ ........................................................................................................................................131
4.2. Weighted apparent sound reduction index R’w ...........................................................................................................131
4.3. Increasing the equivalent absorption area? .................................................................................................................131
4.4. Weighted standardized level difference DnT,w .............................................................................................................132
5. prNBN S01-400-1 (2019): Acoustical criteria for dwellings ..........................................................................132
5.1. Old standards ................................................................................................................................................................132
5.2. Updated Belgian standards ...........................................................................................................................................133
5.3. New European descriptors............................................................................................................................................133
5.4. Acoustical criteria for dwellings (prNBN S 01-400-1:2019) ..........................................................................................135
, 6. Airborne sound insulation of single leaf walls .............................................................................................141
6.1. Transmission of airborne sound through a homogeneous single leaf wall ...................................................................141
7. Airborne sound insulation of double leaf walls ...........................................................................................144
7.1. Design of double leaf constructions: ............................................................................................................................146
7.2. Gyproc plasterboard walls ............................................................................................................................................147
7.3. Timber frame walls .......................................................................................................................................................150
8. Building guidelines .....................................................................................................................................152
8.1. Anchorless cavity wall ...................................................................................................................................................152
8.2. Detailing ........................................................................................................................................................................153
8.3. GypBox-system..............................................................................................................................................................153
8.4. Example of a layout.......................................................................................................................................................155
8.5. Conclusion ....................................................................................................................................................................155
Module 05a Structure borne sound insulation ......................................................................................155
1. Introduction ...............................................................................................................................................155
1.1. Measurement principle ..................................................................................................................................................155
2. Impact sound insulation: Demands from Belgian standard NBN S01-400-1 .................................................157
2.1. Acoustical criteria for dwellings NBN S 01-400-1:2008 & prNBN S 01-400-1:2019 .....................................................157
2.2. Direct hit in contact with the structure ........................................................................................................................161
2.3. Improvement of the structure borne sound transmission in dwellings: intervention at the source: mass-spring systems
(Floating screed) ...........................................................................................................................................................164
2.4. Working principle mass-spring system .........................................................................................................................167
2.5. Determination of the structure borne sound insulation in laboratory conditions .......................................................169
3. Calculations................................................................................................................................................170
3.1. Predictive calculations according to EN 12354-2 ..........................................................................................................170
4. Guidelines ..................................................................................................................................................177
5. Case study ..................................................................................................................................................180
5.1. Case study 1 ..................................................................................................................................................................180
5.2. Case study 2 ..................................................................................................................................................................183
5.3. Case study 3 ..................................................................................................................................................................185
5.4. Stairs & platforms .........................................................................................................................................................185
6. Wooden floors ...........................................................................................................................................186
6.1. Timber frame floors ......................................................................................................................................................186
6.2. CLT floors: cross laminated timber ................................................................................................................................188
6.3. How to reach class A? ...................................................................................................................................................191
7. Conclusions ................................................................................................................................................191
Module 05b Service equipment noise ...................................................................................................192
1. Demands for service equipment noise in dwellings ....................................................................................192
1.1. Acoustical criteria for dwellings NBN S 01-400-1: 2008 ................................................................................................192
1.2. Acoustical criteria for dwellings prNBN S 01-400-1:2019 .............................................................................................196
2. Calculation .................................................................................................................................................198
3. Building guidelines .....................................................................................................................................198
3.1. Limiting service equipment noise in dwellings .............................................................................................................199
3.2. Often appearing complaints … ......................................................................................................................................200
3.3. Other possible equipment noise...................................................................................................................................210
Module 06 Human hearing & Noise on the workplace ..........................................................................211
1. Introduction ...............................................................................................................................................211
1.1. Motivation ....................................................................................................................................................................211
2. Human hearing: Working principle .............................................................................................................213
2.1. Introduction ..................................................................................................................................................................213
2.2. The middle ear ..............................................................................................................................................................214
, 2.3. The inner ear.................................................................................................................................................................215
3. Human hearing: Pathology – what can go wrong? ......................................................................................218
3.1. How can we test it? ......................................................................................................................................................218
3.2. Audiograms ...................................................................................................................................................................219
3.3. Hearing loss ? ................................................................................................................................................................220
3.4. Reality check .................................................................................................................................................................221
3.5. When can you expect hearing loss?..............................................................................................................................221
3.6. Tinniwhatus? ................................................................................................................................................................222
3.7. Tips................................................................................................................................................................................223
4. Human hearing: (individual) hearing protection .........................................................................................223
4.1. Hearing protection ........................................................................................................................................................223
5. Legislation concerning noise on the workplace ...........................................................................................228
5.1. Noise emission by equipment used outdoors ..............................................................................................................228
5.2. Noise on the workplace ................................................................................................................................................230
