PROPAGATION, NOISE CRITERIA

Transcription

1 2 ZVUKOVÁ INDOOR AND IZOLACE OUTDOOR V BUDOVÁCH SOUND PROPAGATION, NOISE CRITERIA kročejový zvuk Course: Building Physics AKUSTIKA V BUDOVÁCH - seminář ČKAIT (03/2017) JIŘÍ NOVÁČEK Department of Building Structures, CTU in Prague Jiří Nováček November 2017 INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 1 40

2 CONTENTS Outdoor Sound Propagation Geometrical Spreading Atmospheric Absorption Ground Reflection x Ground Absorption Attenuation Due to Vegetation Noise Barriers Sound in Enclosed Space Noise Criteria and Limiting Quantities INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 2 40

3 OUTDOOR SOUND PROPAGATION Geometrical Spreading Atmospheric Absorption Effects of Wind and Temperature Gradient Ground Reflection x Absorption Attenuation Due to Vegetation Noise Barriers gradients atmospheric absorption source receiver ground reflection vegetation INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 3 40

4 GEOMETRICAL SPREADING Attenuation depends on a character of sound source: - point sources (mechanical equipment, other at large distances) - line sources (roads) - planar sources (building facades), distance from the source, directivity and source position: FACADE SOURCES* ROOF SOURCES* *or noise sources placed on facades or roofs INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 4 40

5 ATMOSPHERIC ABSORPTION - for long distances r between source and receiver positions - depends on temperature, humidity, atmospheric pressure and frequency A atm r. m - m is an atmospheric absorption rate in db.m -1 or db.km -1 - ISO values of m INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 5 40

6 EFFECTS OF WIND AND TEMPERATURE GRADIENT - vertical gradients bend sound waves upward or downward Wind - the wind speed has no effect on sound propagation in contrast to gradient - acoustic shadow x sound amplification - propagation of sound is not influenced in the perpendicular direction shadow amplification amplification shadow positive gradient negative gradient INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 6 40

7 EFFECTS OF WIND AND TEMPERATURE GRADIENT Temperature amplification hot amplification cool shadow shadow cool hot positive gradient negative gradient INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 7 40

8 height height GROUND REFLECTION X ABSORPTION - reflected sound ray causes either attenuation or amplification - depends on a frequency and a ground character (reflective e. g. water, alphat x absorptive e. g. grass) - common simplification total reflection + 3 db (Q 2) Source direct Receiver reflective ground attenuation reflected attenuation absorptive ground distance distance INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 8 40

9 ATTENUATION DUE TO VEGETATION - trees and forests have no significant attenuating effect - scattering from trunks, limbs and leaves attenuation - wooden area: a) minimum width of 20 meters b) trees staggered close to each other c) dense underbrush - change in attenuation during the winter season! D veg b 19,8log 10 A-weighted correction INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 9 40

10 NOISE BARRIERS Christian Huygens ( ) Dutch mathematician and astronomer INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 10 40

11 NOISE BARRIERS Christian Huygens ( ) Dutch mathematician and astronomer INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 11 40

12 NOISE BARRIERS Augustin Jean Fresnel ( ) French physicist INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 12 40

13 NOISE BARRIERS Augustin Jean Fresnel ( ) French physicist INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 13 40

14 NOISE BARRIERS Augustin Jean Fresnel ( ) French physicist INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 14 40

15 NOISE BARRIERS Augustin Jean Fresnel ( ) French physicist INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 15 40

16 clear shadow fuzzy shadow NOISE BARRIERS source source light sound INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 16 40

17 NOISE BARRIERS INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 17 40

18 NOISE BARRIERS INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 18 40

19 NOISE BARRIERS doc. Čechura INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 19 40

20 NOISE BARRIERS pro pro N. f D100 10log f f 100Hz 1, N Hz 1, N ,5 db D log doc. Čechura ,7 db INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 20 40

21 NOISE BARRIERS pro pro f f N. f Hz N 1000Hz N 0, , ,001 0, ,009 0, ,6 db D100 10log ,6 0,09 0, ,8 db D log doc. Čechura INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 21 40

22 NOISE BARRIERS D ,5 db D ,7 db doc. Čechura D 100 5,6 db D ,8 db D D B D T 16,5 5,6 10,9 db D D B D T 25,7 4,8 20,9 db INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 22 40

23 SOUND IN ENCLOSED SPACES Sound Pressure Level in a Room Cross Section acoustic lining L 1 without acoustic lining sound source L 2 with acoustic lining reverberant sound field direct sound field INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 23 40

24 SOUND IN ENCLOSED SPACES Definition of Diffuse Sound Field - energy is incident from all directions with equal intensities at any position in the room - the intensity of the sound field does not vary with receiver position these simplifications: - allow easy predictions of the sound field characteristics - restrict the use of the model - energy balance in enclosed space: Emitted Sound Power P e I diff,inc Absorbed Sound Power P a I inc p 2 diff 4c INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 24 40

25 SOUND IN ENCLOSED SPACES Steady State - sound pressure does not change with time (continuous sound source after some time) Ceiling Walls P P e a P a Floor Iinc, floors floor floor Iinc, wall1s wall1 wall p diff Iinc Sii 4c i i S i i INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 25 40

26 SOUND IN ENCLOSED SPACES Absorption Coefficient α [-] - the ratio of absorbed sound power P a to the incident sound power P 0 - takes values between 0 and 1 P a P 0 Equivalent Absorption Area A [m 2 ] - the area of a surface with α=1 which gives the same absorbed energy as the surface material under consideration A S S S... i i i S tot m mean absorption coefficient INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 26 40

27 SOUND IN ENCLOSED SPACES Absorption Coefficients of Common Surface Materials Surface - i Frequency f [Hz] Lime plaster on a brick wall 0,030 0,030 0,030 0,040 0,050 0,080 Face brickwork 0,024 0,025 0,032 0,042 0,049 0,070 Wallpaper on a lime plaster on a brick wall 0,02 0,03 0,04 0,05 0,07 0,08 Concrete 0,02 0,02 0,02 0,03 0,04 0,04 Concrete with smooth surface 0,010 0,012 0,015 0,019 0,023 0,035 Gypsum plaster on a brick wall 0,013 0,015 0,020 0,028 0,040 0,050 Marble, granite and other burnished finish 0,010 0,010 0,010-0,015 - Wooden lining 0,010 0,11 0,10 0,08 0,08 0,11 Single glass plate 3 mm thick 0,08 0,04 0,03 0,03 0,02 0,02 Double glass plates 3 mm thick 0,15 0,05 0,03 0,03 0,02 0,02 Wooden floor 0,098 0,110 0,100 0,087 0,082 0,110 PVC floor on hard ground 0,020 0,030 0,030 0,040 0,060 0,050 Carpet Jekor 0,05 0,08 0,10 0,09 0,25 0,38 Water level 0,008 0,008 0,013 0,015 0,020 0,025 Chair with hard backrest 0,020 0,018 0,019 0,021 0,20 0,20 INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 27 40

28 SOUND IN ENCLOSED SPACES Absorptive Objects in Enclosed Space - people, seats, furniture, - must be included in total absorption area of the room: A i S i i j A j - S tot without the surface area of acoustic objects (only boundaries of the room) - acoustic objects closely spaced A j is not the sum of the individual objects - objects with low absorption have scattering effect S tot m diffuse field absorption area of an acoustic object Diffuse reflection INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 28 40

29 SOUND IN ENCLOSED SPACES Energy Balance in Room P e P a p 2 diff 4c i S tot m p 2 diff i 4c S 2 p diff 0,0025 4c Pe 10log 10log Stot m 10 i L L W 10log i 4 S tot m tot m P e INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 29 40

30 SOUND IN ENCLOSED SPACES Complete diffuse field theory - Sabine: L L W Q 10log 2 4r direct field component - rooms with higher values of α m (less reverberant field): L L W Q 10log 2 4r 4 A 4 1 A reverberant field component m - reverberation distance r k [m]: r k AQ 16 1 m INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 30 40

31 SOUND IN ENCLOSED SPACES Computer modelling - image source method source direct receiver 1st reflection image source surface absorption - ray tracing method - the rays radiated from a source are followed, being attenuated, reflected, scattered INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 31 40

32 ENVIRONMENTAL NOISE LEVEL CRITERIA Negative impact of noise on human being - direct and cumulative health effects (annoyance, stress, disturbances communication, relaxation, sleeping) - indirect effects on next generations (disturbed home, social and educational environment) - economic effects (price fall of buildings) - and many others (often problem hidden context with noise) INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 32 40

33 NOISE CRITERIA AND LIMITING QUANTITIES DOMINANT SOUND SOURCES IN BUILT ENVIRONMENT OUTDOOR INDOOR INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 33 40

34 domácí spotřebiče household equipment shodiště stairs bouchání door dveří slams hra na hudební nástroje playing music instruments radio and TV rádia a TV quarrels hádky Rušivost % of annoyed v % dotázaných occupants NOISE CRITERIA AND LIMITING QUANTITIES - noise annoyance in residential buildings Noise sources Charakter zdroje hluku - noise levels of household equipment are not limited by law - some appliances have to be signed with noise data INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 34 40

35 NOISE CRITERIA AND LIMITING QUANTITIES NOISE PREDICTABLE RANDOM e. g. TRAFFIC NOISE EQUIPMENT NOISE e. g. LOUD SPEECH FOOTSTEPS environmental noise level criteria - L Aeq daytime, night-time - L Amax sound insulation criteria - R w - L nw INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 35 40

36 ENVIRONMENTAL NOISE LEVEL CRITERIA Noise Impact on Human Being - objective (intensity, frequency, time) x subjective (information character) - less disturbing are sounds coming into the building from the outside - most disturbing are sounds caused by neighbours - informative character of sound catches the attention of people - three basic limiting values: L Aeq = 85 db L Aeq = 65 db L Aeq = 35 db hearing damage speech communication disturbances sleeping disturbances INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 36 40

37 response response ENVIRONMENTAL NOISE LEVEL CRITERIA L Aeq = 85 db - referes to the time of working period - when exceeded the workplace is classified as risk regarding to noise - if no chance to lower the noise at acceptable level, than workers have to: a) use self-protecting facilities against noise b) have breaks at some quiet place during their working shift c) attend periodic aural medicals noise stimulus stimulus INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 37 40

38 ENVIRONMENTAL NOISE LEVEL CRITERIA INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 38 40

39 SOUND INSULATION - characteristic for indoor environment - types of noise in buildings: a) airborne noise (e. g. loud speech, TV, radio, playing the music instruments, equipment), b) structureborne noise (e. g. footsteps, slammed doors, dropped objects, equipment). Airborne noise is radiated by sources directly into the air. Structureborne noise is produced by sources in mechanical contact with building structures INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 39 40

40 SOUND INSULATION Country CZ Denmark Finland France Netherla nd Germany Portugal Austria Sweden UK R w,walls [db] 53 R w,slabs [db] 53 REQUIREMENTS FOR THE SOUND REDUCTION INDEX BETWEEN DWELLINGS - classes of increased sound insulation of dwellings (CZ): TZZI I. TZZI II. R w 55 db R w 59 db INDOOR AND OUTDOOR SOUND PROPAGATION Jiří Nováček 40 40