1. AN INTRODUCTION TO SOUND AND NOISE
Comenius Project
Torino, October 4° 2012
AN INTRODUCTION TO SOUND AND NOISE
J. Fogola, D. Grasso
Regional Agency for the Protection of the Environment of Piedmont (Arpa Piemonte) 1

2. INTRO Everyday our world is filled with a multitude of sounds
Sound can let us communicate with others or let others communicate with us
It can be a warning of danger or simply an enjoyable experience 2

3. Sound is produced when something vibrates….
WHAT IS SOUND?
Sound is produced when something vibrates…. 3

4. WHAT IS SOUND?
….and generates a sequence of waves of pressure that propagates through compressible media 4

5.    ACOUSTICS SOURCE PROPAGATION RECEIVER
Term derived form Ancient Greek akoustikòs (akoùo, “I hear”)
It’s the branch of physics that deals with the study of the sound
SOURCE 
PROPAGATION  
RECEIVER 5

6. Different physical phenomenon
SOURCES
Different physical phenomenon
Mechanical (bell ringing, explosions,…)
Fluid dynamics (sound from fan,…)
Electromagnetic (magnetostriction in the core of a transformer)
Thermic (boiler combustion,…) 6

7. Sound can propagate through solid, liquid or gas
PROPAGATION
Sound can propagate through solid, liquid or gas
BUT WHAT IS PROPAGATING?
Just energy! 7

8. Speed of sound changes with temperature
PROPAGATION
Speed of sound changes with temperature
Temperature [°C]
-10 10 20 30 40
Speed of sound [m/s]
325
331
337
343
349
355

9. ….and it changes with medium
PROPAGATION
….and it changes with medium
Medium
Steel
Aluminum
Concrete
Rubber
Marble
Wood
Lead
Glass
Density [kg/m3]
7800
2700
2600
11300
Speed of sound [m/s]
5000
5820
35-230
3800
3300
1260

10. Not only human being, but any living form (ecosystem)
RECEIVER
Not only human being, but any living form (ecosystem) 10

11. ACOUSTICS IS MULTIDISCIPLINARY
The combination of different sources, means of propagation and receivers makes the acoustics a multidisciplinary science 11

12. ACOUSTICS APPLICATIONS
HEALTH IN WORKING PLACE
ARCHITECTURE
(theaters, concert halls, buildings,..)
ENGINEERING
(automotive, industry….)
DIAGNOSTICS
(medicine, structural)
ELECTROACUSTIC
(loudspeakers, elect. devices,…)
ACOUSTICS
APPLICATIONS
TELECOMMUNICATION
MILITARY APPLICATIONS
JUSTICE
(phone tapping, identification of the speaker,…
MUSIC
ENVIROMENT 12

13. PROPRIETIES OF SOUND Intensity or Volume (dB)
proportional to the energy of the sound
expressed in a logaritmic scale (dB)
defined ad Sound Pressure Level or SPL
Far from the source
Getting closer 13

14. INTESITY SCALE 14

15. It’s measured in hertz (Hz)
FREQUENCY
Frequency refers to the number of vibrations that an individual particle of the mean of propagation makes in a a second
It’s measured in hertz (Hz) 15

16. FREQUENCY Ecosystem A2 (110 Hz) A3 (220 Hz) A4 (440 Hz) A5 (880 Hz)16

17. FREQUENCY
Each natural or anthropic sound can be decomposed in all the frequencies of the range of human hearing (20 – Hz), such as the natural light can be decomposed in all the visible colors of the rainbow 17

18. Sound pressure level vs Frequency18

19. The sensitivity of the ear changes for the different frequencies
A2 (110 Hz)
A5 (880 Hz)
To take into account of the response of the ear, the dB(A) is introduced dB
dB (A)
SPL is weighed in frequency with the so called “A” curve 19

20. ….but dB(A) is not enough!20 20

21. The human hearing: from a sound event to a hearing event
psychology
physics
psychoacoustics
Sound Event 21

22. Psychoacoustical Aspect
Level, lin.,
A-, B-, C-weighted
Spectral
Contribution
Duration Time
Energy
Subjective
Attitude
Classification
of Sound Event
Temporal
Structure
Signal
Information
Spatial
Distribution
Quantity
Position
Cognitive Aspect
Binaural Aspect
Psychoacoustical Aspect
Physical Aspect
Sound Content 22 22

23. Disturbance within any communication system
SOUND OR NOISE?
Etymologically, the word “noise” can be traced back to the high French period term noyse and to the eleventh century provencal terms, noysa, nosa, nausa, but its origin is still uncertain. The term has a variety of meanings and nuances, the most important are the following:
Unwanted sound
Not musical sound
High intensity sound
Disturbance within any communication system 23

24. SOUND OR NOISE? NOISE = unwanted sound SUBJECTIVE Sound Please
Unplease 24

25. ….it depends from specific culture25

26. ….it depends from specific culture
NOISE = unwanted sound
SUBJECTIVE
The society can fix wanted and unwanted sounds, in relationship to the consensus of the people
The language can show the attitude of a nation to consider a sound as noise or not
(in France the term bruit in used both for the emission of a jet and for the rastle of birds) 26

27. CONTEX is IMPORTANT At 11.00 PM in a concert hall At 11.00 PM
in the bed trying to sleep with the neighbors that listen to music
In the middle of a busy area
In the middle of a park 27

28. EFFECTS OF NOISE Auditory effects > 80 dB(A)
Non-auditory effects < 80 dB(A) 28

29. Aging produces hearing loss!
AUDITORY EFFECTS
Aging produces hearing loss! 29

30. Working and leisure activities can produce hearing loss
AUDITORY EFFECTS
Working and leisure activities can produce hearing loss 30

31. HEARING LOSS IS NOT DEPENDENT ON THE PLEASURE OF LISTENING31

32. …from a scientific study…
AUDITORY EFFECTS
…from a scientific study…
An exposure to 105 dB(A) for 5 years and 4 hours per week, tipical in disco, is comparable to an exposure to 85 dB(A) for 30 years and 40 hours per week, maximum tolerable exposure in a working place for Italian regulation 32

33. AUDITORY EFFECTS
Normal hearing
Hearing loss 33

34. Prevention and protection
SOLUTIONS
In the working places
Prevention and protection 34

35. Keeping low the volume in Limiting exposition in disco and pub
For other activities
Keeping low the volume in
the headphones
Limiting exposition in disco and pub 35

36. Produced by environmental noise
NON-AUDITORY EFFECTS
Produced by environmental noise 36

37. (the example of air traffic noise)
NON-AUDITORY EFFECTS
Influence on sleep
(the example of air traffic noise)
Change of stage (EEG)
Mean motility
Motility after single event
Unconscious awakening (EEG)
Conscious awakening 37

38. Self reported sleep disturbance
NON-AUDITORY EFFECTS
Self reported sleep disturbance 38

39. Reduction of cognitive performance
NON-AUDITORY EFFECTS
Reduction of cognitive performance
A reduction of exposure levels of 5 dB(A), in the range between 65 and 80 dB(A), increases the cognitive performance up to 10% and the attention and the memory up to 2-3% 39

40. NON-AUDITORY EFFECTS Long term effects Cardiovascoular Biological
Mental health 40

41. Bruno Bozzetto presents NEURO41