air and noise pollution

2. Understanding the Basics of Acoustics
• Definition and Scope: Acoustics is the physics branch dedicated to studying sound,
covering its production, transmission, and effects across different mediums.
• Fundamental Concepts: Sound, a mechanical wave, involves compressions and
rarefactions. Key parameters include frequency, wavelength, amplitude, and velocity.
• Components of Sound: Compressions and rarefactions characterize sound waves,
with frequency determining pitch and amplitude correlating with volume.
• Speed of Sound: The speed of sound varies with the medium, approximately 343
meters per second in air at room temperature.
• Acoustic Energy and Applications: Sound carries energy measured in decibels.
Acoustics finds applications in music, communication, medical imaging, and
architectural design.

3. Principles of Acoustic Design and Control
• Room Acoustics: Designing spaces for optimal sound quality
involves considering factors like room shape, size, and surface
materials.
• Importance in Audio Engineering: Acoustics significantly
influences audio engineering, impacting the recording,
mixing, and reproduction of sound in various media. Ongoing
innovations include active noise control and advancements in
virtual acoustics.
• Reflection, Absorption, and Transmission: Acoustic principles include reflection,
absorption, and transmission, crucial for designing sound-favorable spaces.
• Reverberation: Managing reverberation is essential in spaces like auditoriums for
ensuring clarity and intelligibility of sound.
• Noise Control: Noise, unwanted sound, is mitigated through techniques like
soundproofing and noise barriers.

4. The Basics of Sound
• Definition of Sound:
⚬ Sound is the result of vibrating objects that create waves,
which our ears interpret.
⚬ It can travel through air, water, or solids.
• Components of Sound:
⚬ Frequency: Measured in Hertz (Hz), it determines pitch.
⚬ Amplitude: Measured in decibels (dB), it indicates the
loudness of a sound.
• Speed of Sound:
⚬ The speed at which sound waves travel; approximately 343
meters per second in air.
• Wavelength:
⚬ The distance between two points in a sound wave, inversely
related to frequency.

5. Exploring Sound Elements
Frequency Range:
• Describes the span of frequencies a system can reproduce.
• Human hearing range: 20 Hz to 20,000 Hz.
Impedance:
• Measures opposition to current flow, expressed in ohms.
• Matching impedance enhances performance.
Sensitivity:
• Measures how effectively a device converts power into sound
(dB/mW).
Total Harmonic Distortion (THD):
• Indicates distortion during sound reproduction.
• Lower THD values indicate cleaner sound.

6. Parameters for Sound Evaluation
Signal-to-Noise Ratio (SNR)
Higher SNR values mean better
quality
Dynamic Range
Difference between the
loudest and softest sounds
Directionality (for Speakers)
Describes how well a speaker
directs sound to the listener

7. Choosing Audio
Equipment
Consider frequency range, impedance,
sensitivity, and directionality.
Designing Audio
Systems
Optimize dynamic range and
SNR for specific environments
Personal Audio
Preferences
Customize setups for optimal
listening experiences
Environmental Factors
Consider the acoustic properties of the
environment where sound will be experienced
A C
B D

8. What is Sound
Intensity?

9. IntroductiontoSoundWaves
Sound waves are atype of mechanical wave that travels through amedium,such as air or water.They are created by
vibrations that cause pressure changes in the medium,which propagate as waves.The properties of sound waves
include frequency,wavelength, amplitude, and intensity.
• Frequency is the number of waves that pass agiven point in asecond,measured in Hertz (Hz).It determines the
pitch of the sound,with higher frequencies corresponding to higher pitches.
• Wavelength is the distance between two consecutive points on awave that are in phase,measured in meters.It
determines the spatial extent of the wave,with longer wavelengths corresponding to lower frequencies.
• Amplitude is the maximum displacement of awave from its equilibrium position, measured in decibels (dB).It
determines the loudness of the sound,with higher amplitudes corresponding to louder sounds.
• Intensity is the amount of energy that asound wave carries per unit area,measured in watts per square meter
(W/m²).It determines the perceived loudness of the sound,with higher intensities corresponding to louder sounds.

10. Measurement ofSound Intensity
Sound intensity is ameasure of the amount of sound energy that passes through aspecific area in agiven amount of
time.It is also known as sound power per unit area or acoustic intensity.
Units of Sound Intensity
The most common unit used to express sound intensity is the decibel (dB).The decibel scale is logarithmic,which
means that asmall increase in decibel level represents alarge increase in actual sound intensity.
Other units that are sometimes used to express sound intensity include:Watts per square meter (W/m²)Pascals (Pa)Bel
(B)

11. FactorsAffectingSoundIntensity
Sound intensity is affected by several factors, including distance, frequency, and medium.
Distance
The farther away asound source is,
the lower its intensity will be. This is
because sound waves spread out
as they travel, and the energy of the
waves is distributed over alarger
area.As aresult, the sound
becomes quieter as it travels farther
Frequency
The frequency of asound wave also
affects its intensity. Higher
frequency waves tend to be more
intense than lower frequency
waves. This is because higher
frequency waves have more energy
per cycle, which means they can
Medium
Themedium that sound waves
travel through can also affect their
intensity. Sound waves travel faster
and with less resistance through
solids than through liquids or gases.
As aresult, sound waves are
generally more intense in solids

12. SoundIntensity
FactorsAffecting Sound Intensity
Distance:As the distance between the source and the receiver increases,the sound intensity decreases due to the
attenuation of sound waves.
Frequency: Higher frequency sounds have a shorter wavelength and are more easily absorbed by the medium,
resulting in lower sound intensity.
Medium: The properties of the medium,such as density and elasticity, affect the propagation of sound waves and the
resulting sound intensity.

13. UnitsofSoundIntensity
Decibel (dB)
Thedecibel is the most commonly
used unit to express sound
intensity. It is a logarithmic scale
that measures the ratio of the
intensity of asound to areference
level.The higher the decibel value,
the louder the sound.
Advantages:
Disadvantages:
• Easy to understand and use.
• Can be used to compare the
intensity of different sounds.
• Does not take into account the
frequency of the sound.
Bel (B)
Thebel is aunit of sound intensity
that is commonly used in the field of
acoustics.It is defined as the ratio
of the power of asound wave to the
pressure of the sound wave.
Advantages:
Disadvantages:
• Can be used to measure the
intensity of sound waves in
different mediums,such as air,
water,and solids.
• Can be difficult to measure
accurately.
Pascal (Pa)
Thepascal is aunit of pressure,
which can be used to express the
intensity of sound waves.It is
defined as the force exerted per
unit area.
Disadvantages:
Advantages:
• Can be used to measure the
intensity of sound waves in
different mediums,such as air,
water,and solids.
• Can be difficult to measure
accurately.

14. SoundIntensityMeasurement
What is Sound Intensity?
Sound intensity is ameasure of the
power of sound waves per unit area.
It is an important parameter in
various industries, such as
construction, manufacturing, and
healthcare.
Why is Sound Intensity
Measurement Important?
Sound intensity measurement is
important in ensuring the safety and
well-being of workers and the
public. It helps to identify potential
hazards and risks associated with
high levels of sound exposure, such
as hearing loss and tinnitus.
How is Sound Intensity Measured?
Sound intensity is typically
measured using asound level
meter, which is adevice that
converts sound waves into an
electrical signal. The signal is then
analyzed to determine the sound
intensity in decibels per square
meter (dB(A)).

15. ApplicationsofSoundIntensity
Noise Pollution Monitoring
Sound intensity is acrucial factor in measuring and
monitoring noise pollution. This information can be used to
identify areas with excessive noise levels and take
measures to reduce them. Sound intensity meters are
commonly used for this purpose, and they are often
installed in public areas such as parks, schools, and
hospitals.
Acoustic Imaging
Sound intensity can also be used to create images of
sound waves. Acoustic imaging equipment uses sound
intensity data to generate visual representations of sound
waves. This technology has many applications, including in
the medical field for imaging internal organs and in the
automotive industry for testing engine noise and vibration.

16. FutureResearchDirections
 Advancements in Measurement Techniques
Future research in sound intensity could focus on developing new measurement techniques that are more accurate, efficient,
and cost-effective. One potential area of exploration could be the use of machine learning algorithms to improve the
accuracy of measurements, especially in noisy environments. Another area of research could be the development of new
sensors or microphones that are more sensitive and can capture a wider range of frequencies
 Applications in Healthcare and Safety
Sound intensity has important applications in healthcare and safety, and future research could explore
new ways to leverage this technology. For example, researchers could investigate how sound intensity
can be used to monitor the health of patients with respiratory conditions, such as asthma or chronic
obstructive pulmonary disease (COPD). Sound intensity could also be used to improve workplace safety
by detecting and measuring noise levels in industrial settings, helping to prevent hearing loss and other
occupational hazards.

17. Understanding Noise Propagation
•NOISE PROPAGATION REFERS TO HOW SOUND
TRAVELS FROM ITS SOURCE TO THE LISTENER.
•IT CAN BE AFFECTED BY VARIOUS FACTORS,
INCLUDING THE MEDIUM THROUGH WHICH IT
TRAVELS AND THE PRESENCE OF OBSTACLES.

18. Outdoor Noise Propagation
•OUTDOOR NOISE PROPAGATION IS THE
MOVEMENT OF SOUND WAVES THROUGH
THE OUTDOOR ENVIRONMENTS.
•IT CAN BE AFFECTED BY VARIOUS
FACTORS:
A)DISTANCE.
B)WIND.
C)TEMPERATURE.
D)OBSTACLES.

19. Indoor Noise Propagation
INDOOR NOISE PROPAGATION IS THE
MOVEMENT OF SOUND WAVES
THROUGH AN INDOOR ENVIRONMENT.
IT IS INFLUENCED BY:
a) ROOM ACOUSTICS.
b) CONSTRUCTION MATERIAL.
c) SOUND INSULATION MEASURES.
d) SOUND SOURCES .
e) OCCUPANCY.

20. Psychoacoustics & Noise criteria
Psychoacoustics:
Psychoacoustics is the scientific study of how humans perceive and interpret
sound. It involves understanding the psychological and physiological
responses to sound, considering factors such as pitch, loudness, tone, and
duration. The field of psychoacoustics explores the relationship between
physical sound stimuli and the sensations and perceptions they generate in
the human auditory system.

21. Key concepts in psychoacoustics include
1. Loudness Perception: Psychoacoustics examines how the perceived loudness of a
sound corresponds to its physical intensity. The human ear is more sensitive to certain
frequencies, and psychoacoustics helps understand how these frequency sensitivities
contribute to our perception of loudness.
2. Pitch Perception: Psychoacoustics investigates how the frequency of a sound wave
influences our perception of pitch. It considers the tonotopic organization of the
cochlea, where different frequencies are processed in different regions.

22. 3. Masking: This refers to the phenomenon where the presence of one sound (the
masker) makes another sound (the masked signal) less audible. Psychoacoustics
helps analyze how sounds interact and influence each other in terms of perception.
4. Temporal Aspects: Psychoacoustics explores how humans perceive the duration and
timing of sounds, including aspects such as temporal masking and the integration of
auditory information over time.
5. Spatial Hearing: It involves understanding how humans perceive the direction and
location of sounds in space. Binaural hearing and the ability to localize sound sources
are important aspects of spatial hearing.

23. Noise Criteria
Noise Criteria (NC) is a set of curves used to
assess and specify the background noise
levels in a space. The curves are based on
psychoacoustic principles, taking into
account the sensitivity of the human ear to
different frequencies. The purpose of noise
criteria is to provide a standardized method
for evaluating and controlling noise levels in
various environments.

24. Key points regarding Noise Criteria includes
 Standard Curves: The Noise Criteria curves are a set of standardized curves (NC 10 to
NC 80) that represent acceptable levels of background noise in a given space. Each
curve corresponds to a different level of permissible background noise, with higher
numbers indicating greater acceptable noise levels.
 Frequency Bands: The curves are defined for specific one-third octave bands
covering the audible frequency range. This allows for a detailed analysis of the
spectrum of the background noise.
 Application: Noise Criteria are commonly used in the design of buildings and HVAC
(Heating, Ventilation, and Air Conditioning) systems to establish acceptable noise
levels for various types of spaces, such as offices, classrooms, and residential areas.

25.  Occupancy Considerations: The selection of a specific Noise Criteria curve is
influenced by the intended occupancy and use of a space. Different spaces may
have different acceptable levels of background noise based on their function.
By incorporating psychoacoustic principles, Noise Criteria provide a standardized and
human-centered approach to evaluating and controlling background noise levels in
different environments.

26. Annoyance Rating Schemes :
• Annoyance rating schemes are used to measure how annoying a sound is.
• Annoyance ratings are usually given on a scale of 0–10, with higher numbers indicating greater annoyance.
• For example, participants may be asked to rate the annoyance of a sound on a scale of 1–10, where 1 means
"not at all" and 10 means "extremely"
• The annoyance of a sound can depend on the source.
For example, a tram may need to be 3 dBA louder than a bus to have the same annoyance rating.
• Annoyance rating schemes are used to relate the annoyance of noise to the distance between the listener and
the talker.
• They can also include the voice level expected to be used in specific calculated noise levels.
Here are some annoyance rating schemes:
1. 10-point scale :
Participants are asked to rate the annoyance of a stimulus on a scale from 1 (not at all) to 10 (extremely).
2. 7-point scale :
Participants are asked to rate the annoyance of a sound on a scale from 1 (not at all annoying) to 7 (extremely annoying).
3. 100-score graphical rating scale :
Participants are asked to rate the annoyance of a signal on a scale with two poles (not annoying and very annoying) and
three other positions.

27. Noise annoyance can lead to:
The WHO states that noise annoyance leads to anger, disappointment, dissatisfaction, withdrawal,
perceived loss of control or even helplessness, depression, anxiety, distraction, agitation or exhaustion and
sleep disturbance (WHO, 2018).
Difference Between Noise and Annoyance:
• Noise is audible sound that disrupts silence.
• Annoyance is a psychological phenomenon that can be a reaction to noise.
It can also be defined as a feeling of displeasure, nuisance, or irritation.
Annoyance can lead to emotions such as: Frustration, Anger, Slight anger, Irritation, Distraction.
Noise Annoyance Rating Scale

28. NOISE
➢The word noise is derived from the Latin word ‘Nausea’,
which means sickness in which one feels the need to
vomit. Noise is the unpleasant and undesirable sound
which leads to discomfort in human beings. The
intensity of sound is measured in decibels (dB). The
faintest sound that the human ear can hear is 1Db.

29. MEASUREMENT OF NOISE
➢The intensity of sound is measured in terms of sound
pressure level and common unit is decibel.
 Decible (dB) = 10 X
log10(1/Io) I =
Intensity of given
sound
 Io = Intensity of reference sound

30. MEASUREMENT OF NOISE
➢Noise level in decibel is measured with an instrument
called sound level meter (SLM).
➢It is also known as noise meter.

31. MEASUREMENT OF NOISE
➢Noise level in decibel is measured with an instrument
called sound level meter (SLM).
➢It is also known as noise meter.

32. MEASUREMENT OF NOISE
➢SLM Is a digital measuring instrument.
➢It is placed at the place where measurement of noise is
required.
➢The instrument must always be positioned away from direct
source, vibration and from obstruction.
➢After placing it, it gives reading on screen.
➢Once we get the reading then we can compare
them with standards to understand the level of noise.

33. NOISE LEVELS

34. NOISE POLLUTION
➢Due to increasing noise around the civilizations, noise
pollution has become a matter of concern. Some of its
major causes are vehicles, aircraft, industrial machines,
loudspeakers, crackers, etc.
➢When used at high volume, some other appliances
also contribute to noise pollution, like television,
transistor, radio, etc.

35. TYPES OF NOISE POLLUTION
➢Following are the three types of pollution:
➢Transport Noise
➢Neighborhood Noise
➢Industrial Noise

37. Transport Noise
➢It mainly consists of traffic noise which has increased in recent years with the
increase in the number of vehicles. The increase in noise pollution leads to
deafening of older people, headache, hypertension, etc.
Neighborhood Noise
➢The noise from gadgets, household utensils etc. Some of the main sources are
musical instruments, transistors, loudspeakers, etc.
Industrial Noise
➢It is the high-intensity sound which is caused by heavy industrial machines.
According to many researches, industrial noise pollution damages the hearing
ability to around 20%.
TYPES OF NOISE POLLUTION

38. CAUSES AND SOURCES OF NOISE
POLLUTION
➢Following are the causes and sources of noise pollution:
Industrialization: Industrialization has led to an increase in noise pollution
as the use of heavy machinery such as generators, mills, huge exhaust
fans are used, resulting in the production of unwanted noise.
Vehicles: Increased number of vehicles on the roads are the second
reason for noise pollution.
Events: Weddings, public gatherings involve loudspeakers to play music
resulting in the production of unwanted noise in the neighborhood.
Construction sites: Mining, construction of buildings, etc. add to the noise
pollution.

39. NOISE POLLUTION EXAMPLES
Following are the examples of noise pollution:
➢Unnecessary usage of horns
➢Using loudspeakers either for religious functions or for political purposes
➢Unnecessary usage of fireworks
➢Industrial noise
➢Construction noise
➢Noise from transportation such as railway and aircraft

40. EFFECTS OF NOISE POLLUTION ON HUMAN
HEALTH
Noise pollution can be hazardous to human health in the following ways:
➢Hypertension: It is a direct result of noise pollution which is caused due to elevated
blood levels for a longer duration.
➢Hearing loss: Constant exposure of human ears to loud noise that are beyond the
range of sound that human ears can withstand damages the eardrums, resulting in
loss of hearing.
➢Sleeping disorders: Lack of sleep might result in fatigue and low energy level
throughout the day affecting everyday activities. Noise pollution hampers the sleep
cycles leading to irritation and an uncomfortable state of mind.
➢Cardiovascular issues: Heart-related problems such as blood pressure level, stress
and cardiovascular diseases might come up in a normal person and a person
suffering from any of these diseases might feel a sudden shoot up in the level.

41. PREVENTION OF NOISE POLLUTION
 Some noise pollution preventive measures are provided in the points
below.
➢Honking in public places like teaching institutes, hospitals, etc.
should be
 banned.
➢In commercial, hospital, and industrial buildings, adequate
soundproof systems should be installed.
➢Musical instruments’ sound should be controlled to desirable limits.
➢Dense tree cover is useful in noise pollution prevention.
➢Explosives should not be used in forest, mountainous and mining
areas.

42. SPECIAL NOISE ENVIRONMENTS
SPECIAL NOISE ENVIRONMENTS ARE SITUATIONS WHERE THE SOUND
LEVELS OR CHARACTERISTICS ARE UNUSUAL OR EXTREME, AND
MAY POSE A CHALLENGE OR A RISK FOR HUMAN HEALTH AND
WELL-BEING. FOR EG. – UNDERWATER NOISE, TRANSPORTATION
NOISE, RECREATIONAL NOISE AND INDUSTRIAL NOISE.
TYPES OF SPECIAL NOISE ENVIRONMENTS
➢IMPULSIVE SOUND
➢INFRASOUND
➢ULTRASOUND
➢SONIC BOOM

43. Impulsive Sound:
 Impulsive sound is a type of sound that has a very short
duration and a high intensity which usually caused by a
sudden change in pressure or force.
 Common sources include gunshots, hammer strike,
explosions, and industrial processes.
 Prolonged exposure to impulsive noise can lead to
hearing damage and other health issues.
 These sounds often have a high amplitude and can be
significantly louder than the background noise.

44. Infrasound:
 Infrasound is sound that has a frequency below the lower
limit of human hearing, which is generally 20 Hz.
 Infrasound can be produced by natural or human-made
sources, such as earthquakes, volcanoes, thunder,
explosions, aircraft, and machinery.
 Infrasound can have various effects on human health and
well-being, such as nausea, anxiety, fatigue, and hearing
loss.
 We can’t consciously hear Infrasound, it can still affect us
physically and emotionally.
 Infrasound has also been investigated in various fields like
music, where it’s used to create atmospheric effects in
compositions. In scientific studies, it is used to explore its
effect on humans and animals.

45. Ultrasound:
 Ultrasound refers to sound waves with frequencies higher
than the upper limit of human hearing, typically above
20,000 Hz.
 It is widely used in medical imaging for procedures like
ultrasound scans during pregnancy, as well as in industrial
applications for cleaning and measuring distances.
 While humans cannot hear ultrasound, some animals,
such as dogs and bats, can perceive it. This has
applications in animal communication and navigation.
 In industrial and scientific settings, ultrasound is utilized for
non-destructive testing and cleaning delicate items like
jewelry or electronic components.

46. Sonic Boom:
 A sonic boom is a shockwave produced when an object
travels through the air at a speed faster than the speed of
sound.
 It is often associated with supersonic aircraft and can
cause a loud noise similar to an explosion on the ground.
 Sonic booms have led to concerns about their impact on
human health, wildlife, and structures. Efforts are made to
mitigate these effects and control the sonic boom
generated by aircraft.
 Research is ongoing to develop technologies that reduce
or eliminate the sonic boom, allowing for supersonic flight
over land without causing disruptive noise.

47. What Are Noise Standards?
Noise Standards: Guidelines that tell us how much noise is okay in different places.
Purpose:
•Why do we need them?
• Set acceptable noise levels to keep people healthy.
• Make sure our surroundings are safe.
• Protect the environment from too much noise.
Importance in Different Industries:
•How do they help?
• In workplaces: Keep employees safe from loud noises.
• In neighborhoods: Make sure everyone can enjoy a peaceful environment.
• For the planet: Reduce noise pollution to help nature thrive.

48. 1. Workplace Noise Standards - OSHA:
•Example: Occupational Safety and Health Administration (OSHA) sets noise standards for
workplaces.
•Parameters:
• Decibel Levels: For example, OSHA's permissible exposure limit is 90 decibels (dB) for an
8-hour workday.
• Duration: Protects workers from prolonged exposure to loud noise.
2. Community Noise Limits:
•Example: Many communities have specific noise limits to maintain a peaceful environment.
•Parameters:
• Decibel Levels: For instance, residential areas may have nighttime noise limits of 55 dB.
• Duration: Enforced to ensure quiet during sensitive hours.
3. Other Industry-Specific Standards:
•Examples: Explore industry-specific standards relevant to your audience (e.g., construction,
manufacturing).
•Parameters: Highlight specific parameters applicable to those industries.
4. International Standards (Optional):
•Examples: Mention global standards like ISO 1996 for consistent noise measurement.
•Parameters: Show how international standards align with or differ from local regulations.

49. Permissible Limit Values
Central Pollution Control Board (CPCB)
• CPCB of India is an organization under
the Government of India responsible for
Noise quality Monitoring as well setting the
limits of noise which is acceptable for
humans .
• Grades of ambient noise pollution are on
the right according to noise pollution
control and regulation Rules 2000-:

50. Category of Area-:
1. Industrial Areas
• Day time (6:00 AM to 10:00 PM):
• Permissible Limit: 75 dB(A)
• Industrial areas often involve machinery and operations contributing to elevated noise levels.
The permissible limit during the daytime is set to balance industrial activities with the need
for a healthy soundscape.
• Night time (10:00 PM to 6:00 AM):
• Permissible Limit: 70 dB(A)
• Nighttime standards are slightly lower to mitigate the impact on the surrounding residential
areas and promote a quieter environment during rest hours.

51. 2. Commercial Areas
•Day time:
• Permissible Limit: 65 dB(A)
• Commercial areas, with diverse activities and traffic, have a set limit to maintain a balance
between economic activities and the well-being of residents.
•Night time:
• Permissible Limit: 55 dB(A)
• Nighttime standards for commercial zones aim to minimize disturbances during the quieter
hours, fostering a more peaceful environment for nearby residents.
3. Residential Areas
•Day time:
• Permissible Limit: 55 dB(A)
• Residential areas have lower permissible limits during the day to ensure a tranquil living
environment for residents.
•Night time:
• Permissible Limit: 45 dB(A)
• Nighttime standards for residential zones are even lower to promote a restful and peaceful
atmosphere during sleep hours.

52. 4. Silence Zone (e.g., Around Hospitals, Educational Institutions)
•Day time:
• Permissible Limit: 50 dB(A)
• Silence zones, around places like hospitals and educational institutions, have stricter
standards to maintain a calm and conducive environment for healing and learning.
•Night time:
• Permissible Limit: 40 dB(A)
• Lower nighttime standards ensure a quieter atmosphere for essential functions during
nighttime hours
Decibels (dB) often with reference to a standard level. In the context of sound and noise,
decibels are commonly used to measure the intensity or loudness of a sound.
Db(A)-weighting is commonly applied to sound measurements to account for the varying
sensitivity of the human ear to different frequencies. This results in dB(A) measurements, which
are often used in noise regulations and assessments.

53. Noise Measurement Instrumentation
Sound Level Meter (SLM):
● A sound level meter is a primary tool for measuring the intensity of sound in
a given environment. It typically consists of a microphone to capture sound,
an electronic circuit to process the signal, and a display to show the
measured sound levels in decibels (dB).
Noise Dosimeter:
● Unlike a sound level meter, which provides instant measurements, a
noise dosimeter is worn by an individual to assess their personal
exposure to noise over time. It calculates metrics such as equivalent
continuous noise level (Leq) and peak noise levels.
Octave and Frequency Analysis:
○ Some noise measurement instruments provide frequency analysis
capabilities, breaking down the sound into different frequency bands.
This is crucial for identifying the specific frequencies contributing to

55. Noise monitoring procedure

56. • Noise Monitoring is frequently conducted on construction projects ,
industrial sites , and at entertainment venues where there is a risk of
noise pollution to employers or the wider community. All sound that is
harmful to human health or is annoying is considered noise .
• It is important to monitor noise to minimize the impact of your site on
the environment and to demonstrate compliance with the law.
• It is a process to measure the magnitude of noise in industries and
residential area. Data collected from Noise
level monitoring helps us to understand trends and action can be taken
to reduce noise pollution.

57. Noise Measurement and Noise monitoring equipment

58. • Why is Noise Monitoring Important ?
• First and foremost , it safeguards human health.
Prolonged exposure to high levels of noise can lead to hearing loss and
various physiological and psychological disorders, such as stress , sleep
disturbances etc. Noise Monitoring helps ensure compliance with legal
regulations .

59. Noise is Monitored Using a Sound Level Meter(SLM)
This is to measure changes in air pressure , recorded in decibels.
Noise is typically measured by adjusting how a human ear
responds to sound. A sound level meter can measure sound at
different frequencies and record sound clips to determine the
source of noise pollution.

60. Monitoring Procedure
● Install noise monitoring equipment in the area to be
monitored.
● Calibrate the equipment to ensure accurate readings.
● Collect data over a period of time, typically 24-48 hours.
● Analyze the data to determine the level and type of noise
pollution present.

61. Equipment Required
● Sound level meter
● Microphone
● Windscreen
● Calibrator
● Data logging equipment
● Computer with noise analysis software

62. Noise control
 Noise control refers to a set of methods, techniques, and technologies that allows obtaining acceptable
noise levels in a given place, according to economic and operational considerations.
 Noise control does not necessarily imply the reduction of noise emissions—it refers to making
acceptable sound pressure levels of immission (i.e., the signal reaching the receiver).
 When faced with a situation in which the sound pressure levels (SPL) are too high according to the
intended use of a certain place, there are several options for enhancing its acoustic quality. Noise
control solutions can be passive or active

64. 1. ANC refers to a technique that aims to reduce the SPL through the
emission of sound signals in the counter phase with those that occur
in the system to control. Then, destructive interference is generated
between both signals. This method involves adding acoustic energy
to a system that already has an excess of acoustic energy; thus, it
should be applied very carefully. On the other hand, active silencers
are more accurate and versatile than passive ones.
2. Passive control is the most used solution; it aims to dissipate the
excess acoustic energy through absorption, transmission, or
diffusion

65.  There are four basic types of noise control. They are sound insulation, sound absorption, vibration
damping, and vibration isolation.
Sound
Insulation
Vibration
Damping
NOISE CONTROL
Vibration
Damping
Sound
absorbtion

66. • Sound insulation
 This occurs when a solid barrier is introduced to a workspace in an effort to mitigate the amount of
noise and vibration inherent to that environment. This solid barrier helps reduce the reverberation of
the offending sound waves by blocking them.
 The more difficult the solid barrier is to penetrate, the great its efficiency as a form of noise control will
be. As a result, very dense materials such as concrete and steel are often used for this purpose.

67. • Sound absorption
 With this form of noise control, the energy found in sound waves is simply transformed
into heat. A reduction in noise is a natural by-product of this process because the
conversion of sound wave energy into heat energy drastically reduces the amount of
ambient noise left in the environment
 Porous materials are the most effective choice for this process. Like a sponge, these
materials are actually able to absorb the excess sound in the surrounding air

68. • Vibration damping
 It is used to control excess noise and vibration associated with solid surfaces, rather than from actual
sound waves. This process works by extracting the vibration energy from the surface material and
converting it into heat energy. This method of noise control is similar to sound absorption in that it
relies upon energy conversion rather than obstruction.

69. • Vibration isolation
 As the name implies, this method involves
protecting an area or its inhabitants from
the source of unwanted noise or
vibration. Adding a physical barrier to the
workspace is the most common method
of accomplishing this and can be quite
effective as long as the barrier is able to
adequately block the area to be
protected from the source of the
offending noise.