Noise Guidelines: Assessing Low Frequency Noise
Noise guidelines: Assessing low frequency noisePublication 1996 June 2021Authorised and published by EPA VictoriaLevel 3, 200 Victoria Street, Carlton VIC 30531300 372 842 (1300 EPA VIC) epa.vic.gov.auThis publication is for general guidance only. You should obtain professional advice if you haveany specific concern. EPA Victoria has made every reasonable effort to ensure accuracy at thetime of publication.This work is licensed under a Creative Commons Attribution 4.0 licence.Give feedback about this publication online: epa.vic.gov.au/publication-feedbackEPA acknowledges Aboriginal people as the first peoples and Traditionalcustodians of the land and water on which we live, work and depend.We pay respect to Aboriginal Elders, past and present.As Victoria's environmental regulator, we pay respect to how Country hasbeen protected and cared for by Aboriginal people over many tens ofthousands of years.We acknowledge the unique spiritual and cultural significance of land, waterand all that is in the environment to Traditional Owners, and recognise theircontinuing connection to, and aspirations for Country.For languages other than English, please call 131 450.Visit epa.vic.gov.au/language-help for next steps.If you need assistance because of a hearing or speech impairment, please visit relayservice.gov.au2
Noise guidelines: Assessing low frequency noiseContentsGlossary . 5Term . 5Definition . 5Introduction . 9When this guideline applies . 9What is low frequency noise? . 9How low frequency noise affects people . 10Characteristics of low frequency noise that can increase its effect . 10How the effect of low frequency noise varies with your location . 10Common sources of low frequency noise. 11Type . 11Noise source . 11Legislative framework .12Understanding unreasonable noise.12How to reduce low frequency noise levels .12Hierarchy of controls .12Elimination . 13Substitution . 13Engineering controls . 13Administrative controls . 13Proposed industry developments and extension of existing premises . 13Review the proposed equipment . 14Review the proposed installation . 14Predicting low frequency noise . 15Using extrapolation in low frequency noise calculations . 15Threshold levels for assessing low frequency noise . 16Indoor low frequency threshold levels . 16Outdoor low frequency threshold criterion . 16Assessing low frequency noise from existing premises . 17Step 1 – Preliminary evaluation . 19Step 2 – Field assessment. 20Step 3 – Decide where to measure the noise. 20Step 4 – Measure the noise . 20Step 5 – Spectral analysis . 20Step 6 – Consider factor for unreasonable noise .21Step 7 – Assess the noise source of low frequency .213
Noise guidelines: Assessing low frequency noiseStep 8 – Recommendations. 22Step 9 – Assessment report . 22Measurement method .23Noise indicator .23Measurement time .23Measurement duration.23Indoor measurement location and procedure . 24Indoor measurement point(s) . 24Optional corner measurement.25Room conditions .25Indoor measurement procedure .25Outdoor measurement location and procedure . 26Outdoor measurement points . 26Outdoor measurement procedure . 26Microphone setup .28Field calibration checks .28Weather conditions .28Extraneous noise . 29Observation records . 29Audio recordings . 29Measuring equipment . 29Assessing when using equipment with a limited frequency range . 30Assessment report . 31Reporting requirements for noise measurements indoors and outdoors . 31References . 33Victorian Government legislation and publications . 33Australian and international standards . 33Other references . 33Further reading . 344
Noise guidelines: Assessing low frequency noiseGlossaryThis glossary defines the terms for the purpose of this guideline.TermDefinitionCommercial, industrial andtrade premisesIs defined the Regulations and includes any premises except thefollowing: residential premises (other than common plant under thecontrol of an owners’ corporation)a street or road, including every carriageway, footpath,reservation and traffic island on any street or roada railway track used by rolling stock in connection with theprovision of a freight service or passenger service:o while travelling on a railway track or tramway track;oro while entering or exiting a siding, yard, depot orworkshopa railway track used by rolling stock in connection with theprovision of a passenger service, while in a siding, yard,depot or workshop and is:o powering up to commence to be used in connectionwith the provision of a passenger service; oro shutting down after being used in connection withthe provision of a passenger servicethe premises situated at Lower Esplanade, St Kilda, LunaPark, and being the whole of the land more particularlydescribed in Certificate of Title Volume 1204 Folio 109.Note: The maintenance, cleaning or loading of rolling stockstabled in a siding, yard, depot or workshop are included withinthe meaning of commercial, industrial and trade premises.ExamplesCommon plant under the control of an owners’ corporation atresidential premises includes: common air conditioning unitscar stackers and lift equipment in apartment buildings.These must be assessed as noise from commercial, industrial andtrade premises in accordance with the Noise Protocol.5
Noise guidelines: Assessing low frequency noiseTermDefinitionC-frequency weightingFrequency weighting, as specified in Australian standard AS IEC61672.1-2019. that gives more emphasis to low frequency soundsthan the A-frequency weighting.Duty holderThe owner, occupier or person in control of the commercial,industrial or trade premises.Engineering calculationmethodCalculation algorithm relying on a combination of acousticprinciples and empirical relationships. A suitable engineeringcalculation method must have been validated against extensivemeasurement. Also, the set of conditions for which it is fit forpurpose must be documented in a verifiable reference, togetherwith the uncertainty of calculation.ExcitedAn element of a structure vibrating, following an impact or acontact with a moving object.Fast (F) time weightingTime weighting characteristic of a sound level meter as specifiedin Australian Standard AS/NZS IEC 61672.1.Free field conditionsNoise measurement conditions where the sound pressure levelsrecorded by the microphone are not affected by the reflection ofsound on surfaces, other than the ground.FrequencyProperty of sound that measures the rate of repetition of thesound wave, in Hertz (Hz) or cycles per second.Frequency spectrum*Distribution of the energy or the magnitude of a sound acrosseach frequency component.LCeq,TOverall equivalent sound pressure level measured using Cfrequency weighting. As an overall level, it combines the soundenergy of all frequencies.Leq,T (also known as LZeq,T)The equivalent continuous sound pressure level. It is the value ofthe linear or Z-weighted sound pressure level of a continuoussteady sound that has the same acoustic energy as a given timevarying linear or Z-weighted sound pressure level whendetermined over the same measurement time interval T.6
Noise guidelines: Assessing low frequency noiseTermDefinitionLow frequency noiseNoise with low frequency components containing significantacoustic energy within a frequency range defined by one-thirdoctave bands 10 Hz to 160 Hz.Narrow-band spectralanalysisA sound analysis approach based on a high resolution in thefrequency domain such as Fourier analysis or 1/12th octave bandanalysis.Octave bandA division of the frequency range that can be used to analyst ehfrequency spectrum of the measured sound. Noise is measured inoctave bands using frequency filters as specified in AustralianStandard AS IEC 61260.1:2019 Electroacoustics—Octave band andfractional-octave-band filters.One-third octave bandA division of the frequency range that can be used when octavebands don’t provide sufficient resolution. Each octave bandcomprises three one-third octave bands. Noise is measured inone-third octave bands using frequency filters as specified inAustralian Standard AS IEC 61260.1:2019 Electroacoustics—Octaveband and fractional-octave-band filters.Percentile level L10,T, L50,T, L90,T Sound pressure level that is exceeded respectively 10%, 50% and90% of the time during a measurement of duration T.Sensitive receiverThat part of the land within the boundary of a parcel of land thatis outside the external walls of any: dwelling (including a residential care facility) or residentialbuildingdormitory, ward, bedroom or living roomclassroom or any other room in which learning occurs.Or, in the case of a rural area only, that part of the land within theboundary of: Spot measurementsa tourist establishmenta campgrounda caravan park.A survey measurement, typically of short duration, that’sconducted using a handheld sound level meter to get anindication of the sound levels, as they vary within thearea surveyed.7
Noise guidelines: Assessing low frequency noiseTermDefinitionStructure-borne noiseNoise caused by the vibration of the elements of a structure.The source of vibration that results in structure-borne noise iswithin the building where it’s perceived or within a structure withcommon elements that transmit vibration.Threshold of hearingThe level at which an individual can hear a sound at agiven frequency.Unreasonable noiseSection 3(1) of the Act defines unreasonable noise as noise that: Z-frequency weightingis unreasonable having regard to the following:o its volume, intensity or durationo its charactero the time, place and other circumstances in which itis emittedo how often it is emittedo any prescribed factors*, oris prescribed to be unreasonable noise.Means the sound pressure level when no frequency weighting isapplied, as specified in Australian standard AS IEC 61672.1-2019.*Frequency spectrum is a prescribed factor in Regulation 120 of the Environment ProtectionRegulations 2021. It applies to noise from commercial, industrial and trade premises only.8
Noise guidelines: Assessing low frequency noiseIntroductionThis guideline is for acoustic consultants and other qualified professionals who assess lowfrequency noise (10 to 160 Hertz (Hz)). This guideline is also for: duty holders at commercial, industrial and trade premises to understand and manage lowfrequency noise emissionsEPA authorised officers to determine whether the emission of low frequency noise fromcommercial, industrial and trade premises is unreasonable under section 166 of theEnvironment Protection Act 2017 (the Act).Use this guideline to: understand the risk of harm from the emission of low frequency noiseassess and address low frequency noise.This guideline should also be used when you’re designing new commercial, industrial and tradepremises or installing new equipment or plant at existing premises.When this guideline appliesThe assessment methods and guidance set out in this guideline only applies to noise emittedfrom commercial, industrial and trade premises.This guideline does not apply to: music noise from entertainment venuesnoise from residential premisesnoise from wind turbines.The New Zealand Standard NZS 6808:2010 Acoustics – Wind farm noise, or its predecessor NZS6808:1998 Acoustics – The assessment and measurement of sound from wind turbine generatorsis used to assess wind turbine noise.The assessment of low frequency noise using this guideline is separate from an assessment forcompliance with the regulatory noise limits. The regulatory noise limits for commercial, industrialand trade premises are set out in the: Environment Protection Regulations 2021Noise limit and assessment protocol for the control of noise from commercial, industrialand trade premises and entertainment venues (publication 1826)What is low frequency noise?Low frequency noise is often described as rumbling or droning noise. It can be generated bymachinery such as pumps, compressors, diesel engines, fans, generators and boilers. Lowfrequency noise can also be produced by natural sources such as surf in coastal areas and wind.Electrical appliances in homes and buildings, such as refrigerators, can emit low-frequency noise.9
Noise guidelines: Assessing low frequency noiseLow frequency noise may also occur when an object or machine transmits vibration to thestructure of a building, generating ‘structure-borne’ noise. This is when a building’s structuralelements, such as walls or floors vibrates and radiates noise following an impact or a contact witha moving object. The noise can be heard inside other rooms to where the object or machineis housed.In this guideline, low frequency noise is defined as noise with significant acoustic energy in onethird octave bands ranging between 10 Hz to 160 Hz.How low frequency noise affects peopleLow frequency noise can affect people in the same way as other types of noise. This can includesleep disturbance, annoyance, impaired task performance, daytime tiredness, and disturbeddaily cortisol pattern due to stress. These effects can cause some people to experience nauseaand headaches.The human range of hearing is often described as being from 20 Hz to 20,000 Hz (20 kHz).However, low frequency sound at frequencies less than 20 Hz can be audible. Its audibilitydepends on the sound pressure level measured in decibels (dB) and the hearing sensitivity ofwhoever can hear it.Sensitivity to sound varies greatly between individuals. The person investigating low frequencynoise may not hear the sound that someone has reported. However, it may be audible by others.The perceived loudness of low frequency sounds increases rapidly with increasing noise level(measured in decibels). This means low frequency sounds only just above the threshold ofhearing can be perceived as loud by some people (Moorhouse, Waddington and Adams 2011).This doesn’t mean that any audible sound is unreasonable.Characteristics of low frequency noise that can increase its effectCharacteristics that can increase the effects of low frequency noise, particularly how disturbing itis, include: the presence of tones (a sound with energy concentrated at one or two single frequencies,often described as a drone or hum)fluctuating noise level (rapid increase and decrease in noise level)frequency modulation (small variations in the frequency of the noise)rattles or vibration caused by low frequency noise.Low frequency noise with tones can induce greater fatigue and can interfere with taskperformance more than low frequency noise without tones or with the tones masked by othernoise (Leventhall, 2003).How the effect of low frequency noise varies with your locationThe effect of the low frequency noise also varies with the location of where it’s heard. Lowfrequency noise is often experienced indoors. Inside a room, low frequency noise levels can varydue to interference caused by sound reflections on the room surfaces. Sound levels can thenincrease or reduce depending on where a person is positioned. This effect depends on thedimensions of the room and the frequency spectrum of the noise.10
Noise guidelines: Assessing low frequency noiseCommon sources of low frequency noiseThe presence of any of these sources at a premises does not necessarily mean that a lowfrequency noise issue will occur.Table 1: Sources of low frequency noiseTypeNoise sourceCommercial/industrial/trade aircraftblastingboilerscooling towerscooling fanscompressorsdiesel engineselectrical installationsextraction fansheavy machinerylarge generatorsloading and unloading activitiesmetal thuddingmotorspower stationspumpsshipping and ships in the harborsteam releasesshakerstransformersventilation plantvibratory screensResidential air conditionerselectric appliancesfish tank pumpsheat pumpsrefrigeratorspa bath pumpsNatural causes sea, including surfseismic activitythunderwindwind effects on structures11
Noise guidelines: Assessing low frequency noiseLegislative frameworkUnder section 166 of the Act, a person must not emit an unreasonable noise or permit anunreasonable noise to be emitted from any place or premises that is not residential premises.Understanding unreasonable noiseNoise is assessed as being unreasonable having regard to the characteristics of the noise andthe circumstances in which it is emitted, as defined under unreasonable noise in section 3(1) ofthe Act.An assessment of unreasonable noise can also include any prescribed factors. Regulation 120 ofthe Environment Protection Regulations 2021 (the Regulations) makes frequency spectrum aprescribed factor when assessing noise from commercial, industrial and trade premises. Thefrequency spectrum from 10 Hz to 160 Hz must be used to assess whether the low frequency noiseis unreasonable.Other factors which may be considered in an assessment include: how often the noise occurshow long the noise continuesits character such as the presence of tones, fluctuations, or pulsing.If an authorised officer reasonably believes that unreasonable noise has been or is being emitted,the officer may issue an improvement or prohibition notice to the duty holder.How to reduce low frequency noise levelsIf a low frequency sound can be traced to a known source, this increases the potential to takeaction to reduce the noise.Hierarchy of controlsThe hierarchy of controls is a step-by-step approach to eliminate or reduce risk, includingcontrols from the highest level of protection, elimination, to the lowest, administrative controls.Figure 1: Hierarchy of controls12
Noise guidelines: Assessing low frequency noiseEliminationElimination is the most effective way to address potential hazards and risksfrom low frequency noise. Avoiding harmful noise emissions through plantdesign and siting is an example of elimination. Another example isimplementing an effective inspection and maintenance plan to preventissues occurring, due to equipment malfunction or wearing.SubstitutionSubstitution involves replacing a process or equipment that generates lowfrequency noise with an alternative with lower hazard and risk. For example,replacing a noisy machine at a premises with a quieter one.Engineering controlsThe use of engineering controls includes using isolation to reduce thehazard and risk of low frequency noise, for example: installing silencers that are specifically designed for low frequency noisemitigationadding damping to panels of equipment enclosuresreplacing rubber mountings or fittings, to reduce vibration transmission.Administrative controlsAdministrative controls are actions that aim to lessen the potential for harmfrom a hazard or risk through training, policy, procedure, or change inoperating practices. For example, operating noisy processes during the dayas opposed to the evening or night periods.Proposed industry developments and extension of existing premisesThe risk of unreasonable noise generated by low frequency noise is often difficult to predict fornew premises. Therefore, the design of existing or proposed commercial, industrial and tradepremises should consider unreasonable noise from low frequencies being emitted beyond theboundaries of the premises.Low frequency noise issues can be difficult and more expensive to address once they haveoccurred. Therefore, design features and measures to minimise low frequency noise should beincorporated at the very beginning of a project.When planning and designing a commercial, industrial and trade premises development, whetherit’s a new premises or an extension of existing premises, it’s essential to understand the hazardand risk of emission from low frequency noise.13
Noise guidelines: Assessing low frequency noiseActions to minimise hazard and risk from low frequency noise should be documented andsupported by an assessment report, prepared by a suitably qualified acoustic consultantor practitioner.Justification for the design should be provided in the development proposal, planningapplication, and/or environmental management plans.Review the proposed equipmentUnderstanding the hazards and risks associated with the proposed equipment is key topreventing and mitigating the emission of low frequency noise. This can be done by: reviewing the literature available, asking manufacturers and industry peersand understanding:o the character and risk of low frequency noise emissions from theproposed equipmento which alternative equipment or process can be used to minimise low frequencynoise emissionso how to avoid or minimise low frequency noise emissionso the potential noise mitigation measures and their effectiveness.conducting measurements of the same or similar equipment at already existing facilities.This can provide valuable information on the:o hazard and risk of low frequency noise emissionso potential tones within the low frequency range of 10 Hz to 160 Hz that maybe problematic.Review the proposed installationThe planning and design stage of an installation is when the most effective noise elimination orminimisation measures can be incorporated. Things to consider in the review of any proposedinstallation include: 14plan for installation, set-up, and operation of all equipment according to manufacturer’sinstructions, and following industry best practice to minimise the generat
Noise guidelines: Assessing low frequency noise 2 Publication 1996 June 2021 Authorised and published by EPA Victoria Level 3, 200 Victoria Street, Carlton VIC 3053 1300 372 842 (1300 EPA VIC) epa.vic.gov.au This publication is for general guidance only. You should obtain professional advice if you have any specific concern.
Noise Figure Overview of Noise Measurement Methods 4 White Paper Noise Measurements The noise contribution from circuit elements is usually defined in terms of noise figure, noise factor or noise temperature. These are terms that quantify the amount of noise that a circuit element adds to a signal.
Figure 1: Power spectral density of white noise overlaid by flicker noise. Figure 2: Flicker noise generated from white noise. 1.1 The nature of flicker noise Looking at processes generating flicker noise in the time domain instead of the frequency domain gives us much more insight into the nature of flicker noise.
The Noise Element of a General Plan is a tool for including noise control in the planning process in order to maintain compatible land use with environmental noise levels. This Noise Element identifies noise sensitive land uses and noise sources, and defines areas of noise impact for the purpose of
7 LNA Metrics: Noise Figure Noise factor is defined by the ratio of output SNR and input SNR. Noise figure is the dB form of noise factor. Noise figure shows the degradation of signal's SNR due to the circuits that the signal passes. Noise factor of cascaded system: LNA's noise factor directly appears in the total noise factor of the system.
noise and tire noise. The contribution rate of tire noise is high when the vehicle is running at a constant speed of 50 km/h, reaching 86-100%, indicating tire noise is the main noise source [1]. Therefore, reducing tire noise is important for reducing the overall noise of the vehicle and controlling noise pollution [2].
state laser. At modulation frequencies well below the locking frequency we find significant frequency-noise reduction, and at modulation frequencies above the locking frequency we find that the frequency noise is that of the free-running slave laser. Our intensity-noise theory predicts substantial damping of relaxation oscillations in the slave .
to the problem we have observed in the ADS phase noise simulation where the pnmx phase noise goes flat below some small offset frequency.) The plot to the right shows the phase noise for πf 2 c π 10 -3 osc. Note if we were to extrapolate from the phase noise at 100 kHz, we would get a phase noise of 30 dBc/Hz at an offset frequency of 1 Hz.
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