SlideShare a Scribd company logo
Environmental Acoustics:
Noise
Decibels and levels
dB Scales
Acoustic power
Intensity and Pressure
Dr. Priyanka Tabhane
Department of Physics
Rashtrasant Tukadoji Maharaja Nagpur
University, Nagpur
Noise
• Noise is the unpitched sound.
• Noise is made of combined output of a great number of sound
sources of widely different frequencies.
Noise can be objectionable in several ways-
• It causes loss of intelligibility in the conversation because of
lack of attention.
• It may cause masking of desired sounds.
• It may cause hearing damage.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
What are Decibels (dB)?
• Decibel deci (1/10th) + bel (Alexander Graham Bell)
• A decibel (dB) is a ratio between two quantities that has been
reported on a logarithmic scale.
• dB allows a realistic modeling of human auditory perception,
since the ear reacts to relative changes in noise level.
• It is used to express the ratio of one value of a power or root-
power quantity to another, on a logarithmic scale.
• A logarithmic quantity in decibels is called a level.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
dB Scales in acoustics
• Sound is measured in units called decibels (dB).
• The higher the decibel level, the louder the noise.
• On the decibel scale, the level increase of 10 means that a
sound is actually 10 times more intense, or powerful.
• The ear mechanism is able to respond to both very small and
very large pressure waves by virtue of being nonlinear.
• Ear responds much more efficiently to sounds of very small
amplitude than to sounds of very large amplitude.
• Because of the enormous nonlinearity of the ear in sensing
pressure waves, a nonlinear scale is convenient in describing
the intensity of sound waves.
• Such a scale is provided by the decibel level of a sound wave.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
• The human ear is more sensitive to the sound in the frequency
range 1kHz to 4kHz.
• The knowledge about the human ear is important in acoustic
design and sound measurements.
• To compensate for human hearing, sound meters are normally
fitted with filters that adapts the measured sound response to
human sense of sound. The common filters are dB(A), dB(B)
and dB(C).
‘A’ Weighting-
• The decibel A filter roughly corresponds to inverse of 40 dB
(at 1kHz) equal loudness curve for human ear.
• With dB(A) filter, the sound level meter is less sensitive to
very high and very low frequencies.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
• The measurement made with this scale is called as dB(A).
• ‘A’ Weighting is standard weighting of the audible frequencies
designed to reflect the response of the human ear to noise.
• At low and high frequencies, the human ear is not very sensitive,
but between 500 Hz and 6 kHz the ear is much more sensitive.
• The ‘A’ weighting filter covers the full frequency range of 20 Hz
to 20 kHz, but the shape approximates to the frequency
sensitivity of the human ear.
• So the A-weighted value of a noise source is an approximation
to how the human ear perceives the noise.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
‘C’ Weighting-
• The decibel C filter is linear over several octaves
and is suitable for subjective measurements at
very high sound pressure levels.
• Measurements made using ‘C’ weighting are
usually shown with dB(C) to show that the
information is ‘C’ weighted decibels.
‘B’ Weighting-
• The decibel B filter is between C and A. The B
and C filters are seldom used.
• ‘B’ weighting is a flat frequency response
between 10Hz and 20kHz.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
• Compared with dB, A-weighted measurements underestimate the
perceived loudness, annoyance factor and stress-inducing capability
of noises with low frequency components, especially at moderate
and high volumes of noise.
• A fundamental feature of this type of logarithmic scale is that each
unit of increase in the decibel scale corresponds to an increase in
absolute intensity. Thus, an increase in absolute intensity from 10−12
to 10−11W/𝑚2 corresponds to an increase of 10 decibels, as does an
increase from 10−1 to 1 W/𝑚2.
• The correlation between the absolute intensity of a sound wave and
its decibel level along with examples of sounds at each level is
shown in Table.
• When the defining level of 0 decibel (10−12W/𝑚2) is taken to be at
the threshold of hearing for a sound wave with a frequency of 1kHz,
then 130 decibels (10 W/𝑚2) corresponds to the threshold of feeling,
or the threshold of pain.
• Although the decibel scale is nonlinear, it is directly measurable, and
sound-level meters are available for that purpose.
• Sound levels for audio systems, architectural acoustics, and other
industrial applications are most often quoted in decibels.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
Sound Power or Acoustic Power
• Sound power is the energy rate, or energy of sound per unit of time (W
in SI-units) - emitted by a source.
• Sound power can more practically be expressed in a logarithmic scale
named Sound Power Level as the ratio of sound power to the sound
power at the threshold of hearing:
where,
𝐿𝑁= Sound Power Level (decibel , dB)
N = sound power (W)
𝑁𝑟𝑒𝑓= reference sound power (10−12𝑊)
The lowest sound power persons with excellent hearing can listen is
about10-12W - defined as 0 dB in the decibel scale
The loudest sound power generally possible to encounter is that of a jet
aircraft with a sound power of 105W - 170 dB
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
Sound Intensity or Acoustic Intensity
• Sound intensity is defined as the power carried by sound waves per
unit area in the direction perpendicular to that area. The unit is watts
per square meter W/𝑚2.
• Human hearing is directly sensitive to sound pressure which is
related to sound intensity. Sound intensity level is a logarithmic
expression of sound intensity relative to a reference intensity.
• Sound intensity I is
𝐼=𝑃𝑣
where, P is the sound pressure and v is the particle velocity.
• The sound intensity level is given by the formula
Where, 𝐼𝑟𝑒𝑓=10−12 𝑊/𝑚2 which is also audible to human ear.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
Sound Pressure or Acoustic Pressure
• The sound pressure is the force of a sound on a surface area
perpendicular to the direction of the sound. The SI-unit for the
Sound Pressure is Pa.
• A variation in pressure above and below atmospheric pressure
at the ear is called sound pressure.
• The normal ear is most sensitive at frequencies between 1kHz
to 4kHz, and a young person can detect pressures as low as
about 20𝜇Pa, which, when compared to the normal
atmospheric pressure (101.3×103𝑃𝑎) around which it varies, is
a fractional variation of 2×10−10.
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur
The Sound Pressure Level in decibel can be expressed as
Where,
𝐿𝑝= sound pressure level (dB)
p = sound pressure (Pa)
𝑝𝑟𝑒𝑓=2×10−5 - reference sound pressure (Pa)
Dr. Priyanka Tabhane
Department of Physics
RTM Nagpur University, Nagpur

More Related Content

What's hot

Remote sensing
Remote sensingRemote sensing
Remote sensing
Siva Rajah
 
From filtered back-projection to statistical tomography reconstruction
From filtered back-projection to statistical tomography reconstructionFrom filtered back-projection to statistical tomography reconstruction
From filtered back-projection to statistical tomography reconstruction
Daniel Pelliccia
 
Physics of Ultrasound Imaging
Physics of Ultrasound ImagingPhysics of Ultrasound Imaging
Physics of Ultrasound Imaging
u.surgery
 
Noise
NoiseNoise
Echo cancellation
Echo cancellationEcho cancellation
Echo cancellation
Ahmed Shelbaya
 
Artifacts and Bioeffects
Artifacts and Bioeffects Artifacts and Bioeffects
Artifacts and Bioeffects
Nusirat Adedewe
 
Basics of MRI Physics
Basics of MRI PhysicsBasics of MRI Physics
Basics of MRI Physics
yasna kibria
 
Part1and 2 Mri Registry Review
Part1and 2 Mri Registry ReviewPart1and 2 Mri Registry Review
Part1and 2 Mri Registry Review
woor6j
 
Radioactivity and nuclear transformation
Radioactivity and nuclear transformationRadioactivity and nuclear transformation
Radioactivity and nuclear transformation
Shahid Younas
 
Noise Performance of CW system
Noise Performance of CW systemNoise Performance of CW system
Noise Performance of CW system
Dr Naim R Kidwai
 
MicroStrip Patch Antenna
MicroStrip Patch AntennaMicroStrip Patch Antenna
MicroStrip Patch Antenna
Amit Kirti saran
 
Basics of mri
Basics of mriBasics of mri
Basics of mri
Ganesh Nair
 
Nuclear Medicine Procedures-3
Nuclear Medicine Procedures-3Nuclear Medicine Procedures-3
Nuclear Medicine Procedures-3
Ashraf Zytoon
 
Biograph mCT-PET - SIEMENS
Biograph mCT-PET - SIEMENSBiograph mCT-PET - SIEMENS
Biograph mCT-PET - SIEMENS
Jhon Arriaga Cordova
 
Gamma Camera Image Quality
Gamma Camera Image QualityGamma Camera Image Quality
Gamma Camera Image Quality
David Graff
 
Mri safety
Mri safetyMri safety
Mri safety
shokoofeh mousavi
 
Mri hardware
Mri hardwareMri hardware
Mri hardware
Shail Padmani
 
BIS CHAPTER ONE.pptx
BIS CHAPTER ONE.pptxBIS CHAPTER ONE.pptx
BIS CHAPTER ONE.pptx
Tirusew1
 
PHYSICS OF ULTRASOUND AND KNOBOLOGY
PHYSICS OF ULTRASOUND AND KNOBOLOGYPHYSICS OF ULTRASOUND AND KNOBOLOGY
PHYSICS OF ULTRASOUND AND KNOBOLOGY
Arun Babu
 
FACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptx
FACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptxFACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptx
FACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptx
Rohit Bansal
 

What's hot (20)

Remote sensing
Remote sensingRemote sensing
Remote sensing
 
From filtered back-projection to statistical tomography reconstruction
From filtered back-projection to statistical tomography reconstructionFrom filtered back-projection to statistical tomography reconstruction
From filtered back-projection to statistical tomography reconstruction
 
Physics of Ultrasound Imaging
Physics of Ultrasound ImagingPhysics of Ultrasound Imaging
Physics of Ultrasound Imaging
 
Noise
NoiseNoise
Noise
 
Echo cancellation
Echo cancellationEcho cancellation
Echo cancellation
 
Artifacts and Bioeffects
Artifacts and Bioeffects Artifacts and Bioeffects
Artifacts and Bioeffects
 
Basics of MRI Physics
Basics of MRI PhysicsBasics of MRI Physics
Basics of MRI Physics
 
Part1and 2 Mri Registry Review
Part1and 2 Mri Registry ReviewPart1and 2 Mri Registry Review
Part1and 2 Mri Registry Review
 
Radioactivity and nuclear transformation
Radioactivity and nuclear transformationRadioactivity and nuclear transformation
Radioactivity and nuclear transformation
 
Noise Performance of CW system
Noise Performance of CW systemNoise Performance of CW system
Noise Performance of CW system
 
MicroStrip Patch Antenna
MicroStrip Patch AntennaMicroStrip Patch Antenna
MicroStrip Patch Antenna
 
Basics of mri
Basics of mriBasics of mri
Basics of mri
 
Nuclear Medicine Procedures-3
Nuclear Medicine Procedures-3Nuclear Medicine Procedures-3
Nuclear Medicine Procedures-3
 
Biograph mCT-PET - SIEMENS
Biograph mCT-PET - SIEMENSBiograph mCT-PET - SIEMENS
Biograph mCT-PET - SIEMENS
 
Gamma Camera Image Quality
Gamma Camera Image QualityGamma Camera Image Quality
Gamma Camera Image Quality
 
Mri safety
Mri safetyMri safety
Mri safety
 
Mri hardware
Mri hardwareMri hardware
Mri hardware
 
BIS CHAPTER ONE.pptx
BIS CHAPTER ONE.pptxBIS CHAPTER ONE.pptx
BIS CHAPTER ONE.pptx
 
PHYSICS OF ULTRASOUND AND KNOBOLOGY
PHYSICS OF ULTRASOUND AND KNOBOLOGYPHYSICS OF ULTRASOUND AND KNOBOLOGY
PHYSICS OF ULTRASOUND AND KNOBOLOGY
 
FACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptx
FACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptxFACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptx
FACTORS AFFECTING THE SIGNAL-TO-NOISE RATIO.pptx
 

Similar to Environmental Acoustics- noise decible scale intensity pressure

Speech, hearing, noise, intelligibility.pptx
Speech, hearing, noise, intelligibility.pptxSpeech, hearing, noise, intelligibility.pptx
Speech, hearing, noise, intelligibility.pptx
priyankatabhane
 
audiology.pptx
audiology.pptxaudiology.pptx
audiology.pptx
Dr vivek Malpani
 
Environmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptxEnvironmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptx
priyankatabhane
 
LECT 4 - SOUND, ACOUSTIC AND NOISE.pptx
LECT 4 -  SOUND, ACOUSTIC AND NOISE.pptxLECT 4 -  SOUND, ACOUSTIC AND NOISE.pptx
LECT 4 - SOUND, ACOUSTIC AND NOISE.pptx
julaidakaliwon
 
Noise pollution_2.ppt
Noise pollution_2.pptNoise pollution_2.ppt
Noise pollution_2.ppt
PapuKumarNaik1
 
unit 4.pdf
unit 4.pdfunit 4.pdf
unit 4.pdf
Jaideep491
 
Audiometry class by Dr. Kavitha Ashok Kumar MSU Malaysia
Audiometry class by Dr. Kavitha Ashok Kumar MSU MalaysiaAudiometry class by Dr. Kavitha Ashok Kumar MSU Malaysia
Audiometry class by Dr. Kavitha Ashok Kumar MSU Malaysia
Kavitha Ashokb
 
Acoustic, audiology
Acoustic, audiologyAcoustic, audiology
Acoustic, audiology
Tarun Kumar Dwibedi
 
Pure tone audiometry
Pure tone audiometryPure tone audiometry
Pure tone audiometry
drdhiman2
 
Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...
Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...
Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...
ajengpuspitasari1992
 
Comfort and loudness measures
Comfort and loudness measuresComfort and loudness measures
Comfort and loudness measures
bethfernandezaud
 
Octave band.pptx
Octave band.pptxOctave band.pptx
Octave band.pptx
Chandu794921
 
Pure tone audiometry
Pure tone audiometryPure tone audiometry
Pure tone audiometry
Balasubramanian Thiagarajan
 
Sound and hearing
Sound and hearingSound and hearing
Sound and hearing
dessyjoy25
 
Brainstem Auditory Evoked Potentials Part II
Brainstem Auditory Evoked Potentials Part IIBrainstem Auditory Evoked Potentials Part II
Brainstem Auditory Evoked Potentials Part II
Anurag Tewari MD
 
Audiometry Ashly
Audiometry  AshlyAudiometry  Ashly
Audiometry Ashly
ashlyalexanderkiran
 
Noise_its_control.ppt
Noise_its_control.pptNoise_its_control.ppt
Noise_its_control.ppt
DevendraSingh673501
 
Audiological tests of hearing assessment
Audiological tests of hearing assessmentAudiological tests of hearing assessment
Audiological tests of hearing assessment
DRRamendrakumarSingh
 
7. Audiometry Dr. Krishna Koirala
7. Audiometry Dr. Krishna Koirala7. Audiometry Dr. Krishna Koirala
7. Audiometry Dr. Krishna Koirala
krishnakoirala4
 
Audiometry for Undergraduate and postgraduate ENT students
Audiometry for Undergraduate and postgraduate ENT students Audiometry for Undergraduate and postgraduate ENT students
Audiometry for Undergraduate and postgraduate ENT students
Dr Krishna Koirala
 

Similar to Environmental Acoustics- noise decible scale intensity pressure (20)

Speech, hearing, noise, intelligibility.pptx
Speech, hearing, noise, intelligibility.pptxSpeech, hearing, noise, intelligibility.pptx
Speech, hearing, noise, intelligibility.pptx
 
audiology.pptx
audiology.pptxaudiology.pptx
audiology.pptx
 
Environmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptxEnvironmental Acoustics- Speech interference level, acoustics calibrator.pptx
Environmental Acoustics- Speech interference level, acoustics calibrator.pptx
 
LECT 4 - SOUND, ACOUSTIC AND NOISE.pptx
LECT 4 -  SOUND, ACOUSTIC AND NOISE.pptxLECT 4 -  SOUND, ACOUSTIC AND NOISE.pptx
LECT 4 - SOUND, ACOUSTIC AND NOISE.pptx
 
Noise pollution_2.ppt
Noise pollution_2.pptNoise pollution_2.ppt
Noise pollution_2.ppt
 
unit 4.pdf
unit 4.pdfunit 4.pdf
unit 4.pdf
 
Audiometry class by Dr. Kavitha Ashok Kumar MSU Malaysia
Audiometry class by Dr. Kavitha Ashok Kumar MSU MalaysiaAudiometry class by Dr. Kavitha Ashok Kumar MSU Malaysia
Audiometry class by Dr. Kavitha Ashok Kumar MSU Malaysia
 
Acoustic, audiology
Acoustic, audiologyAcoustic, audiology
Acoustic, audiology
 
Pure tone audiometry
Pure tone audiometryPure tone audiometry
Pure tone audiometry
 
Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...
Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...
Sound Level Meters.pptx Sound Level Meters.pptx Sound Level Meters.pptx Sound...
 
Comfort and loudness measures
Comfort and loudness measuresComfort and loudness measures
Comfort and loudness measures
 
Octave band.pptx
Octave band.pptxOctave band.pptx
Octave band.pptx
 
Pure tone audiometry
Pure tone audiometryPure tone audiometry
Pure tone audiometry
 
Sound and hearing
Sound and hearingSound and hearing
Sound and hearing
 
Brainstem Auditory Evoked Potentials Part II
Brainstem Auditory Evoked Potentials Part IIBrainstem Auditory Evoked Potentials Part II
Brainstem Auditory Evoked Potentials Part II
 
Audiometry Ashly
Audiometry  AshlyAudiometry  Ashly
Audiometry Ashly
 
Noise_its_control.ppt
Noise_its_control.pptNoise_its_control.ppt
Noise_its_control.ppt
 
Audiological tests of hearing assessment
Audiological tests of hearing assessmentAudiological tests of hearing assessment
Audiological tests of hearing assessment
 
7. Audiometry Dr. Krishna Koirala
7. Audiometry Dr. Krishna Koirala7. Audiometry Dr. Krishna Koirala
7. Audiometry Dr. Krishna Koirala
 
Audiometry for Undergraduate and postgraduate ENT students
Audiometry for Undergraduate and postgraduate ENT students Audiometry for Undergraduate and postgraduate ENT students
Audiometry for Undergraduate and postgraduate ENT students
 

More from priyankatabhane

Microphone- characteristics,carbon microphone, dynamic microphone.pptx
Microphone- characteristics,carbon microphone, dynamic microphone.pptxMicrophone- characteristics,carbon microphone, dynamic microphone.pptx
Microphone- characteristics,carbon microphone, dynamic microphone.pptx
priyankatabhane
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptx
priyankatabhane
 
Environmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxEnvironmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptx
priyankatabhane
 
Architectural acoustics, underwater acoustics
Architectural acoustics, underwater acousticsArchitectural acoustics, underwater acoustics
Architectural acoustics, underwater acoustics
priyankatabhane
 
Fundamentals of Ultrasonic waves and applications
Fundamentals of Ultrasonic waves and applicationsFundamentals of Ultrasonic waves and applications
Fundamentals of Ultrasonic waves and applications
priyankatabhane
 
Lec 4 digital electronics - interated circuit technology -characteristics o...
Lec 4   digital electronics - interated circuit technology -characteristics o...Lec 4   digital electronics - interated circuit technology -characteristics o...
Lec 4 digital electronics - interated circuit technology -characteristics o...
priyankatabhane
 
Lec 3 digital electronics- read only memory
Lec 3  digital electronics- read only memoryLec 3  digital electronics- read only memory
Lec 3 digital electronics- read only memory
priyankatabhane
 
Lec 2 digital electronics - random access memory
Lec 2  digital electronics - random access memoryLec 2  digital electronics - random access memory
Lec 2 digital electronics - random access memory
priyankatabhane
 
Lec 1 digital electroinics - memory array, write read operations
Lec 1   digital electroinics - memory array, write read operationsLec 1   digital electroinics - memory array, write read operations
Lec 1 digital electroinics - memory array, write read operations
priyankatabhane
 

More from priyankatabhane (9)

Microphone- characteristics,carbon microphone, dynamic microphone.pptx
Microphone- characteristics,carbon microphone, dynamic microphone.pptxMicrophone- characteristics,carbon microphone, dynamic microphone.pptx
Microphone- characteristics,carbon microphone, dynamic microphone.pptx
 
Loudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptxLoudspeaker- direct radiating type and horn type.pptx
Loudspeaker- direct radiating type and horn type.pptx
 
Environmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptxEnvironmental acoustics- noise criteria.pptx
Environmental acoustics- noise criteria.pptx
 
Architectural acoustics, underwater acoustics
Architectural acoustics, underwater acousticsArchitectural acoustics, underwater acoustics
Architectural acoustics, underwater acoustics
 
Fundamentals of Ultrasonic waves and applications
Fundamentals of Ultrasonic waves and applicationsFundamentals of Ultrasonic waves and applications
Fundamentals of Ultrasonic waves and applications
 
Lec 4 digital electronics - interated circuit technology -characteristics o...
Lec 4   digital electronics - interated circuit technology -characteristics o...Lec 4   digital electronics - interated circuit technology -characteristics o...
Lec 4 digital electronics - interated circuit technology -characteristics o...
 
Lec 3 digital electronics- read only memory
Lec 3  digital electronics- read only memoryLec 3  digital electronics- read only memory
Lec 3 digital electronics- read only memory
 
Lec 2 digital electronics - random access memory
Lec 2  digital electronics - random access memoryLec 2  digital electronics - random access memory
Lec 2 digital electronics - random access memory
 
Lec 1 digital electroinics - memory array, write read operations
Lec 1   digital electroinics - memory array, write read operationsLec 1   digital electroinics - memory array, write read operations
Lec 1 digital electroinics - memory array, write read operations
 

Recently uploaded

Embracing Deep Variability For Reproducibility and Replicability
Embracing Deep Variability For Reproducibility and ReplicabilityEmbracing Deep Variability For Reproducibility and Replicability
Embracing Deep Variability For Reproducibility and Replicability
University of Rennes, INSA Rennes, Inria/IRISA, CNRS
 
Synopsis presentation VDR gene polymorphism and anemia (2).pptx
Synopsis presentation VDR gene polymorphism and anemia (2).pptxSynopsis presentation VDR gene polymorphism and anemia (2).pptx
Synopsis presentation VDR gene polymorphism and anemia (2).pptx
FarhanaHussain18
 
The cost of acquiring information by natural selection
The cost of acquiring information by natural selectionThe cost of acquiring information by natural selection
The cost of acquiring information by natural selection
Carl Bergstrom
 
Nutaceuticsls herbal drug technology CVS, cancer.pptx
Nutaceuticsls herbal drug technology CVS, cancer.pptxNutaceuticsls herbal drug technology CVS, cancer.pptx
Nutaceuticsls herbal drug technology CVS, cancer.pptx
vimalveerammal
 
Physiology of Nervous System presentation.pptx
Physiology of Nervous System presentation.pptxPhysiology of Nervous System presentation.pptx
Physiology of Nervous System presentation.pptx
fatima132662
 
seed production, Nursery & Gardening.pdf
seed production, Nursery & Gardening.pdfseed production, Nursery & Gardening.pdf
seed production, Nursery & Gardening.pdf
Nistarini College, Purulia (W.B) India
 
23PH301 - Optics - Unit 2 - Interference
23PH301 - Optics - Unit 2 - Interference23PH301 - Optics - Unit 2 - Interference
23PH301 - Optics - Unit 2 - Interference
RDhivya6
 
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptx
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptxTOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptx
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptx
shubhijain836
 
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
frank0071
 
Reaching the age of Adolescence- Class 8
Reaching the age of Adolescence- Class 8Reaching the age of Adolescence- Class 8
Reaching the age of Adolescence- Class 8
abhinayakamasamudram
 
Lattice Defects in ionic solid compound.pptx
Lattice Defects in ionic solid compound.pptxLattice Defects in ionic solid compound.pptx
Lattice Defects in ionic solid compound.pptx
DrRajeshDas
 
Polycythemia vera_causes_disorders_treatment.pptx
Polycythemia vera_causes_disorders_treatment.pptxPolycythemia vera_causes_disorders_treatment.pptx
Polycythemia vera_causes_disorders_treatment.pptx
muralinath2
 
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfMending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
Selcen Ozturkcan
 
Male reproduction physiology by Suyash Garg .pptx
Male reproduction physiology by Suyash Garg .pptxMale reproduction physiology by Suyash Garg .pptx
Male reproduction physiology by Suyash Garg .pptx
suyashempire
 
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...
Creative-Biolabs
 
AJAY KUMAR NIET GreNo Guava Project File.pdf
AJAY KUMAR NIET GreNo Guava Project File.pdfAJAY KUMAR NIET GreNo Guava Project File.pdf
AJAY KUMAR NIET GreNo Guava Project File.pdf
AJAY KUMAR
 
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
Sérgio Sacani
 
Quality assurance B.pharm 6th semester BP606T UNIT 5
Quality assurance B.pharm 6th semester BP606T UNIT 5Quality assurance B.pharm 6th semester BP606T UNIT 5
Quality assurance B.pharm 6th semester BP606T UNIT 5
vimalveerammal
 
2001_Book_HumanChromosomes - Genéticapdf
2001_Book_HumanChromosomes - Genéticapdf2001_Book_HumanChromosomes - Genéticapdf
2001_Book_HumanChromosomes - Genéticapdf
lucianamillenium
 
Signatures of wave erosion in Titan’s coasts
Signatures of wave erosion in Titan’s coastsSignatures of wave erosion in Titan’s coasts
Signatures of wave erosion in Titan’s coasts
Sérgio Sacani
 

Recently uploaded (20)

Embracing Deep Variability For Reproducibility and Replicability
Embracing Deep Variability For Reproducibility and ReplicabilityEmbracing Deep Variability For Reproducibility and Replicability
Embracing Deep Variability For Reproducibility and Replicability
 
Synopsis presentation VDR gene polymorphism and anemia (2).pptx
Synopsis presentation VDR gene polymorphism and anemia (2).pptxSynopsis presentation VDR gene polymorphism and anemia (2).pptx
Synopsis presentation VDR gene polymorphism and anemia (2).pptx
 
The cost of acquiring information by natural selection
The cost of acquiring information by natural selectionThe cost of acquiring information by natural selection
The cost of acquiring information by natural selection
 
Nutaceuticsls herbal drug technology CVS, cancer.pptx
Nutaceuticsls herbal drug technology CVS, cancer.pptxNutaceuticsls herbal drug technology CVS, cancer.pptx
Nutaceuticsls herbal drug technology CVS, cancer.pptx
 
Physiology of Nervous System presentation.pptx
Physiology of Nervous System presentation.pptxPhysiology of Nervous System presentation.pptx
Physiology of Nervous System presentation.pptx
 
seed production, Nursery & Gardening.pdf
seed production, Nursery & Gardening.pdfseed production, Nursery & Gardening.pdf
seed production, Nursery & Gardening.pdf
 
23PH301 - Optics - Unit 2 - Interference
23PH301 - Optics - Unit 2 - Interference23PH301 - Optics - Unit 2 - Interference
23PH301 - Optics - Unit 2 - Interference
 
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptx
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptxTOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptx
TOPIC OF DISCUSSION: CENTRIFUGATION SLIDESHARE.pptx
 
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
Juaristi, Jon. - El canon espanol. El legado de la cultura española a la civi...
 
Reaching the age of Adolescence- Class 8
Reaching the age of Adolescence- Class 8Reaching the age of Adolescence- Class 8
Reaching the age of Adolescence- Class 8
 
Lattice Defects in ionic solid compound.pptx
Lattice Defects in ionic solid compound.pptxLattice Defects in ionic solid compound.pptx
Lattice Defects in ionic solid compound.pptx
 
Polycythemia vera_causes_disorders_treatment.pptx
Polycythemia vera_causes_disorders_treatment.pptxPolycythemia vera_causes_disorders_treatment.pptx
Polycythemia vera_causes_disorders_treatment.pptx
 
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfMending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdf
 
Male reproduction physiology by Suyash Garg .pptx
Male reproduction physiology by Suyash Garg .pptxMale reproduction physiology by Suyash Garg .pptx
Male reproduction physiology by Suyash Garg .pptx
 
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...
Mechanisms and Applications of Antiviral Neutralizing Antibodies - Creative B...
 
AJAY KUMAR NIET GreNo Guava Project File.pdf
AJAY KUMAR NIET GreNo Guava Project File.pdfAJAY KUMAR NIET GreNo Guava Project File.pdf
AJAY KUMAR NIET GreNo Guava Project File.pdf
 
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...
 
Quality assurance B.pharm 6th semester BP606T UNIT 5
Quality assurance B.pharm 6th semester BP606T UNIT 5Quality assurance B.pharm 6th semester BP606T UNIT 5
Quality assurance B.pharm 6th semester BP606T UNIT 5
 
2001_Book_HumanChromosomes - Genéticapdf
2001_Book_HumanChromosomes - Genéticapdf2001_Book_HumanChromosomes - Genéticapdf
2001_Book_HumanChromosomes - Genéticapdf
 
Signatures of wave erosion in Titan’s coasts
Signatures of wave erosion in Titan’s coastsSignatures of wave erosion in Titan’s coasts
Signatures of wave erosion in Titan’s coasts
 

Environmental Acoustics- noise decible scale intensity pressure

  • 1. Environmental Acoustics: Noise Decibels and levels dB Scales Acoustic power Intensity and Pressure Dr. Priyanka Tabhane Department of Physics Rashtrasant Tukadoji Maharaja Nagpur University, Nagpur
  • 2. Noise • Noise is the unpitched sound. • Noise is made of combined output of a great number of sound sources of widely different frequencies. Noise can be objectionable in several ways- • It causes loss of intelligibility in the conversation because of lack of attention. • It may cause masking of desired sounds. • It may cause hearing damage. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 3. What are Decibels (dB)? • Decibel deci (1/10th) + bel (Alexander Graham Bell) • A decibel (dB) is a ratio between two quantities that has been reported on a logarithmic scale. • dB allows a realistic modeling of human auditory perception, since the ear reacts to relative changes in noise level. • It is used to express the ratio of one value of a power or root- power quantity to another, on a logarithmic scale. • A logarithmic quantity in decibels is called a level. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 4. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 5. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 6. dB Scales in acoustics • Sound is measured in units called decibels (dB). • The higher the decibel level, the louder the noise. • On the decibel scale, the level increase of 10 means that a sound is actually 10 times more intense, or powerful. • The ear mechanism is able to respond to both very small and very large pressure waves by virtue of being nonlinear. • Ear responds much more efficiently to sounds of very small amplitude than to sounds of very large amplitude. • Because of the enormous nonlinearity of the ear in sensing pressure waves, a nonlinear scale is convenient in describing the intensity of sound waves. • Such a scale is provided by the decibel level of a sound wave. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 7. • The human ear is more sensitive to the sound in the frequency range 1kHz to 4kHz. • The knowledge about the human ear is important in acoustic design and sound measurements. • To compensate for human hearing, sound meters are normally fitted with filters that adapts the measured sound response to human sense of sound. The common filters are dB(A), dB(B) and dB(C). ‘A’ Weighting- • The decibel A filter roughly corresponds to inverse of 40 dB (at 1kHz) equal loudness curve for human ear. • With dB(A) filter, the sound level meter is less sensitive to very high and very low frequencies. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 8. • The measurement made with this scale is called as dB(A). • ‘A’ Weighting is standard weighting of the audible frequencies designed to reflect the response of the human ear to noise. • At low and high frequencies, the human ear is not very sensitive, but between 500 Hz and 6 kHz the ear is much more sensitive. • The ‘A’ weighting filter covers the full frequency range of 20 Hz to 20 kHz, but the shape approximates to the frequency sensitivity of the human ear. • So the A-weighted value of a noise source is an approximation to how the human ear perceives the noise. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 9. ‘C’ Weighting- • The decibel C filter is linear over several octaves and is suitable for subjective measurements at very high sound pressure levels. • Measurements made using ‘C’ weighting are usually shown with dB(C) to show that the information is ‘C’ weighted decibels. ‘B’ Weighting- • The decibel B filter is between C and A. The B and C filters are seldom used. • ‘B’ weighting is a flat frequency response between 10Hz and 20kHz. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 10. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 11. • Compared with dB, A-weighted measurements underestimate the perceived loudness, annoyance factor and stress-inducing capability of noises with low frequency components, especially at moderate and high volumes of noise. • A fundamental feature of this type of logarithmic scale is that each unit of increase in the decibel scale corresponds to an increase in absolute intensity. Thus, an increase in absolute intensity from 10−12 to 10−11W/𝑚2 corresponds to an increase of 10 decibels, as does an increase from 10−1 to 1 W/𝑚2. • The correlation between the absolute intensity of a sound wave and its decibel level along with examples of sounds at each level is shown in Table. • When the defining level of 0 decibel (10−12W/𝑚2) is taken to be at the threshold of hearing for a sound wave with a frequency of 1kHz, then 130 decibels (10 W/𝑚2) corresponds to the threshold of feeling, or the threshold of pain. • Although the decibel scale is nonlinear, it is directly measurable, and sound-level meters are available for that purpose. • Sound levels for audio systems, architectural acoustics, and other industrial applications are most often quoted in decibels. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 12. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 13. Sound Power or Acoustic Power • Sound power is the energy rate, or energy of sound per unit of time (W in SI-units) - emitted by a source. • Sound power can more practically be expressed in a logarithmic scale named Sound Power Level as the ratio of sound power to the sound power at the threshold of hearing: where, 𝐿𝑁= Sound Power Level (decibel , dB) N = sound power (W) 𝑁𝑟𝑒𝑓= reference sound power (10−12𝑊) The lowest sound power persons with excellent hearing can listen is about10-12W - defined as 0 dB in the decibel scale The loudest sound power generally possible to encounter is that of a jet aircraft with a sound power of 105W - 170 dB Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 14. Sound Intensity or Acoustic Intensity • Sound intensity is defined as the power carried by sound waves per unit area in the direction perpendicular to that area. The unit is watts per square meter W/𝑚2. • Human hearing is directly sensitive to sound pressure which is related to sound intensity. Sound intensity level is a logarithmic expression of sound intensity relative to a reference intensity. • Sound intensity I is 𝐼=𝑃𝑣 where, P is the sound pressure and v is the particle velocity. • The sound intensity level is given by the formula Where, 𝐼𝑟𝑒𝑓=10−12 𝑊/𝑚2 which is also audible to human ear. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 15. Sound Pressure or Acoustic Pressure • The sound pressure is the force of a sound on a surface area perpendicular to the direction of the sound. The SI-unit for the Sound Pressure is Pa. • A variation in pressure above and below atmospheric pressure at the ear is called sound pressure. • The normal ear is most sensitive at frequencies between 1kHz to 4kHz, and a young person can detect pressures as low as about 20𝜇Pa, which, when compared to the normal atmospheric pressure (101.3×103𝑃𝑎) around which it varies, is a fractional variation of 2×10−10. Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur
  • 16. The Sound Pressure Level in decibel can be expressed as Where, 𝐿𝑝= sound pressure level (dB) p = sound pressure (Pa) 𝑝𝑟𝑒𝑓=2×10−5 - reference sound pressure (Pa) Dr. Priyanka Tabhane Department of Physics RTM Nagpur University, Nagpur