[701-0662-00 V] Environmental Impacts, Threshold Levels and Health Effects Lecture 8: Noise - Part 2 (08.04.2020) Mark Brink ETH Zürich D-USYS Homepage: http://www.noise.ethz.ch/ei/ D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 1
Topics covered in the previous lecture • Overview over Part 2 ("Noise") of the lecture • Physical basics: Sound pressure and sound pressure level • The Decibel scale, Decibel arithmetic • Perceivable changes of sound pressure level • Anatomy of the ear • Principles of auditory perception • Basilar membrane, hair cells • Gestalt-principles of auditory perception D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 2
Lecture overview for today ► Physical and subjective description of sound ► Sound pressure level measurement ► The measures SPL, L eq , L max , SEL (L E ) Frequency weighting filters and Time constants ► ► Demonstration with Sound Level Meter ► Noise – introduction ► Transportation noise situation in Switzerland Noise exposure statistics in the Canton of Zurich ► ► Time variation of road traffic noise exposure ► Effectiveness of noise abatement measures ► Measurement and calculation of (transportation) noise Measurement and calculation of noise exposure ► ► Sound propagation and attenuation ► Noise maps / noise contours D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 3
Physical and subjective description of sound D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 4
Physical and subjective descriptions of "sound volume" Sound Physical description Subjective description Sound Sound Sound Loudness pressure power intensity – Unit: sone – Unit: Pa – Unit: W – Unit: Wm -2 Sound Sound Sound Loudness level pressure power intensity – Unit: Phon level – Unit: dB level – Unit: dB level – Unit: dB D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 5
Auditory sensation area Sound pressure level at the ear [dB] Threshold of pain Dynamic range Musical perception Speech perception 0 dB = 0.00002 Pa D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 6
Equal loudness curves (German "Kurven gleicher Lautstärke") Hearing threshold D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 7
Sound pressure level: common measures D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 8
Sound pressure level measurement Sound level meter (SLM) Calculation (sonBASE noise map) D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 9
Most common measures SPL (Current) Sound pressure level (over time) L max Maximum level within measurement period (also called „SEL“) Sound Exposure Level (Total energy of L E a defined sound event) L eq Equivalent Continuous Sound Level (energetic average) L E /SEL SPL in dB L max L Aeq time Measurement period D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 10
Statistical Measures L 10 , L 50 , L 90 Note that L 10 > L 50 > L 90 D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 11
Frequency weighting filters +20 +0 Attenuation [dB] C -20 B -40 A -60 10 100 1'000 10'000 Frequency [Hz] → "dB(A)" always means: A -weighted measurement D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 12
Time constants (FAST and SLOW) FAST (125 ms) SLOW (1 sec) → L AF means: A-weighted, FAST → L AS means: A-weighted, SLOW D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 13
Demonstrations with sound level meter D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 14
Noise exposure D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 15
... lets start with road traffic noise Road traffic is the single most dominant noise source worldwide! D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 16
Course of 1h-Leq of road traffic noise over a week 1h-Leq Vehicles per hour % trucks D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 17
Diurnal variation of annual average daily traffic AADT in CH average at 307 automatic traffic counting stations 15 14 Median 25%-75% 13 Min-Max 12 11 Percent of AADT [%] 10 9 8 7 6 5 4 3 2 1 0 _ H00 H02 H04 H06 H08 H10 H12 H14 H16 H18 H20 H22 H01 H03 H05 H07 H09 H11 H13 H15 H17 H19 H21 H23 Hour of the day D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 18
Doubling the number of events leads to an increase of 3 dB Leq 70 dB(A) 65 60 3 dB 55 50 45 40 35 30 1 25 50 75 100 125 150 175 200 225 250 Number of vehicles per hour D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 19
Range of maximum sound pressure levels L max (at a distance of 7.5 m) Car Pickup/Van Bus Light truck Heavy truck Motorbike D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 20
Effectiveness of noise abatement measures 0 dB Cut traffic by half (3 dB) Speed reductions (up to 3dB) 5 dB Low noise pavement (1 - 5dB ) 2 m noise barrier (5 - 10dB ) 10 dB 4 m noise barrier (10 - 15dB ) 15 dB 20 dB 25 dB 30 dB Encasing/encapsulation ( > 30dB ) 35 dB 40 dB D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 21
Sound attenuation outdoors – indoors D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 22
Sound attenuation outdoors – indoors Sound-proof windows 30-40 dB attenuation D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 23
Road traffic as noise source Tires Engine vibrations Power train Fan Air intake and muffler Three types of sources: - Engine and transmission noise: dominant during acceleration, in low gears - Tire/road noise: dominates on community roads and highways - Aerodynamic noise: only at high speeds D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 24
Railways as noise source Ripples on rails D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 25
Railways as noise source Cast iron brake pad Synthetic brake pads Disk brake D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 26
Aircraft as noise source Engines Flaps Landing gear D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 27
Noise footprints at landing and take off D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 28
Measurement and calculation of noise exposure Brüel&Kjaer 2236 Integrating CADNA-A calculation of exposure precision sound level meter contours on the computer D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 29
Calculation of noise exposure Basic principles L W Distance source-receiver L AE Emission Immission Traffic figures, Radar tracks etc.. L Aeq Source Receiver D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 30
Measurement of sources with microphone arrays acoustic camera D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 31
Measurement of sources with microphone arrays D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 32
Sound propagation Influence of wind and temperature gradient cold Day warm warm Night cold D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 33
Influencing factors in sound propagation Temperature ± 1 dB Throttle pos. ± 1 dB Humidity ± 1 dB Wind ± 5 dB Reflections Situational conditions Attenuation Airport D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 34
Most frequently used average measures of noise exposure used in noise legislation in CH (partly), the EU, the US... • L eq This is the basic measure: Average level over a certain time period • L eq,24 h Average level over 24 hours, 00-24 h • L Day Leq in the period 07-23 h (Switzerland 06-22 h) • L Night Leq in the period 23-07 h (Switzerland 22-06 h) "Noise metrics" • L DN (DNL) Day-Night Level: L 07-22h + 0 dB L 22-07h + 10 dB penalty • L DEN (DENL) Day-Evening-Night Level: L 07-19h + 0 dB L 19-23h + 5 dB penalty L 23-07h + 10 dB penalty D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 35
Most frequently used average measures of noise exposure Formulas for L eq,24 h , L DN , and L DEN ( ) ( ) 16 8 0.1 L 0.1 L L =10 lg 10 Day + 10 Night eq,24 h 24 24 used in USA 15 9 ( ) ( ) 0.1 Leq +0 0.1 Leq +10 L =10 lg 10 + 10 07-22h 22-07h DN 24 24 used in EU ( ) ( ) ( ) 12 4 8 0.1 L +0 0.1 L +5 0.1 L +10 L =10 lg 10 eq,07-19h + 10 eq,19-23h + ×10 eq,23-07h DEN 24 24 24 D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 36
Distribution of noise levels in Switzerland (Year 2010) Road traffic noise Number of people 400'000 L_day L_night 350'000 L_den L_dn 300'000 250'000 200'000 150'000 100'000 50'000 0 40 45 50 55 60 65 70 75 80 Exposure in dB(A) D- USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 37
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