[701-0662-00 V] Environmental Impacts, Threshold Levels ...701-0662-00L]Lecture08-Brink-Noise-Slides.pdf · D-USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 3 Physical

D-USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 1

[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/

http://www.noise.ethz.ch/ei/


• 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

Topics covered in the previous lecture


► Physical and subjective description of sound

► Sound pressure level measurement

► The measures SPL, Leq, Lmax, SEL (LE)

► 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

Lecture overview for today


Physical and subjective

description of sound


Physical and subjective descriptions of "sound volume"

Soundpressurelevel – Unit: dB

Soundpowerlevel – Unit: dB

Soundintensitylevel – Unit: dB

Soundpressure

– Unit: Pa

Soundpower

– Unit: W

Soundintensity

– Unit: Wm-2

Physical description Subjective description

Loudness– Unit: sone

Loudness level– Unit: Phon

Sound


Sound p

ressure

level at th

e e

ar

[dB

]

Dyn

am

ic r

an

ge

0 dB = 0.00002 Pa

Auditory sensation area

Musical perception

Speech perception

Threshold of pain


Equal loudness curves (German "Kurven gleicher Lautstärke")

Hearing threshold


Sound pressure level:

common measures


Sound pressure level measurement

Sound level meter (SLM) Calculation (sonBASE noise map)


Most common measures

SPL (Current) Sound pressure level (over time)

Lmax Maximum level within measurement period

LE (also called „SEL“) Sound Exposure Level (Total energy of

a defined sound event)

Leq Equivalent Continuous Sound Level (energetic average)

time

SP

L in d

B

Measurement period

LE/SEL

Lmax

LAeq


Statistical Measures L10, L50, L90

Note that L10 > L50 > L90


Frequency weighting filters

Att

en

uati

on

[d

B]

Frequency [Hz]

+20

+0

-20

-40

-60

10 100 1'000 10'000

A

B

C

→ "dB(A)" always means: A-weighted measurement


Time constants (FAST and SLOW)

→ LAF means: A-weighted, FAST

→ LAS means: A-weighted, SLOW

FAST (125 ms)

SLOW (1 sec)


Demonstrations with sound level meter


Noise exposure


... lets start with road traffic noise

Road traffic is the single most

dominant noise source worldwide!


Course of 1h-Leq of road traffic noise over a week

1h-Leq

Vehicles per hour

% trucks


Diurnal variation of annual average daily traffic AADT in CH

H00

H01

H02

H03

H04

H05

H06

H07

H08

H09

H10

H11

H12

H13

H14

H15

H16

H17

H18

H19

H20

H21

H22

H23

Hour of the day

_

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Pe

rce

nt

of

AA

DT

[%

]

Median

25%-75%

Min-Max

average at 307 automatic traffic counting stations


Number of vehicles per hour

LeqdB(A)

25 50 75 100 125 150 175 200 225 250

30

35

40

45

50

55

60

65

70

1

3 dB

Doubling the number of events leads to an increase of 3 dB


Range of maximum sound pressure levels Lmax

(at a distance of 7.5 m)

Car

Pickup/Van

Bus

Light truck

Heavy truck

Motorbike


0 dB

35 dB

40 dB

15 dB

5 dB

25 dB

30 dB

20 dB

10 dB

Encasing/encapsulation ( > 30dB )

4 m noise barrier (10 - 15dB )

2 m noise barrier (5 - 10dB )

Low noise pavement (1 - 5dB )

Cut traffic by half (3 dB)Speed reductions (up to 3dB)

Effectiveness of noise abatement measures


Sound attenuation outdoors – indoors


Sound attenuation outdoors – indoors

Sound-proof windows

30-40 dB attenuation


TiresEngine vibrations

Fan

Air intake and muffler

Power train

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

Road traffic as noise source


Ripples on rails

Railways as noise source


Railways as noise source

Cast iron brake pad Synthetic brake pads Disk brake


Flaps

Landing gear

Engines

Aircraft as noise source


Noise footprints at landing and take off


Brüel&Kjaer 2236 Integrating

precision sound level meterCADNA-A calculation of exposure

contours on the computer

Measurement and calculation of noise exposure


LW Distance source-receiver

LAE

ReceiverSource

Traffic figures,

Radar tracks etc..

LAeq

Calculation of noise exposureBasic principles

Emission Immission


Measurement of sources with microphone arrays

acoustic camera


Measurement of sources with microphone arrays


Influence of wind and temperature gradient

cold

warm

warm

cold

Day

Night

Sound propagation

http://upload.wikimedia.org/wikipedia/de/2/2f/Refraktion_dh.png


Airport

Temperature ± 1 dB

Wind ± 5 dBHumidity ± 1 dB

Throttle pos. ± 1 dB

Attenuation

ReflectionsSituational conditions

Influencing factors in sound propagation


• Leq This is the basic measure: Average level over a certain time period

• Leq,24 h Average level over 24 hours, 00-24 h

• LDay Leq in the period 07-23 h (Switzerland 06-22 h)

• LNight Leq in the period 23-07 h (Switzerland 22-06 h)

Most frequently used average measures of noise exposureused in noise legislation in CH (partly), the EU, the US...

• LDN (DNL) Day-Night Level:

L07-22h + 0 dB

L22-07h + 10 dB penalty

• LDEN (DENL) Day-Evening-Night Level:

L07-19h + 0 dB



"Noise metrics"


Most frequently used average measures of noise exposureFormulas for Leq,24 h , LDN , and LDEN

( ) ( )

07-22h 22-07h0.1 Leq +0 0.1 Leq +10

DN

15 9L =10 lg 10 + 10

24 24

( ) ( ) ( )

eq,07-19h eq,19-23h eq,23-07h0.1 L +0 0.1 L +5 0.1 L +10

DEN

12 4 8L =10 lg 10 + 10 + ×10

24 24 24

( ) ( )Day Night0.1 L 0.1 L

eq,24 h

16 8L =10 lg 10 + 10

24 24

used in USA

used in EU


0

50'000

100'000

150'000

200'000

250'000

300'000

350'000

400'000

40 45 50 55 60 65 70 75 80

Number of people

Exposure in dB(A)

L_day

L_night

L_den

L_dn

Distribution of noise levels in Switzerland

(Year 2010)Road traffic noise


Distribution of noise levels in Switzerland

(Year 2010)Railway noise

0

20'000

40'000

60'000

80'000

100'000

120'000

140'000

160'000

180'000

200'000

40 45 50 55 60 65 70 75 80

Number of people

Exposure in dB(A)

L_day

L_night

L_den

L_dn


1-Stunden-Leq von 55 dBN

Noise exposure contours on a mapAuckland, NZ

Auckland, NZ


Road traffic noise mapSursee, Kanton Luzern


Road traffic noise mapBrussels, Belgium


Road traffic noise during day

sonBASE (Swiss noise mapping database)

80 dB(A)

0 dB(A)


Rail traffic noise during day


80 dB(A)

0 dB(A)


Aircraft noise


Zurich Airport

Euro Airport Basel

Geneva Airport

Payerne (Air Force)

Sion (Air Force)

Meiringen (Air Force)

Documents

[701-0662-00 V] Environmental Impacts, Threshold Levels ...701-0662-00L]Lecture08-Brink-Noise-Slides.pdf · D-USYS • M. Brink • Environmental Impacts - Noise Part 2 Slide 3 Physical