Appendix 4.10-A: Basics of Noise and Vibration
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Design of Digital Filters for Frequency Weightings (A and C) Required for Risk Assessments of Workers Exposed to Noise
Industrial Health 2015, 53, 21–27 Original Article Design of digital filters for frequency weightings (A and C) required for risk assessments of workers exposed to noise Andrew N. RIMELL1, Neil J. MANSFIELD2* and Gurmail S. PADDAN3 1Aero Engine Controls, Rolls-Royce, UK 2Loughborough Design School, Loughborough University, UK 3Institute of Naval Medicine, UK Received January 4, 2013 and accepted August 18, 2014 Published online in J-STAGE September 13, 2014 Abstract: Many workers are exposed to noise in their industrial environment. Excessive noise ex- posure can cause health problems and therefore it is important that the worker’s noise exposure is assessed. This may require measurement by an equipment manufacturer or the employer. Human exposure to noise may be measured using microphones; however, weighting filters are required to correlate the physical noise sound pressure level measurements to the human’s response to an audi- tory stimulus. IEC 61672-1 and ANSI S1.43 describe suitable weighting filters, but do not explain how to implement them for digitally recorded sound pressure level data. By using the bilinear transform, it is possible to transform the analogue equations given in the standards into digital fil- ters. This paper describes the implementation of the weighting filters as digital IIR (Infinite Impulse Response) filters and provides all the necessary formulae to directly calculate the filter coefficients for any sampling frequency. Thus, the filters in the standards can be implemented in any numeri- cal processing software (such as a spreadsheet or programming language running on a PC, mobile device or embedded system). Key words: Hearing loss, IEC 61672-1, ANSI S1.43, Occupational health and safety, Noise measurement, Frequency weighting, Digital filter loss if the correct protective measures are not in place. -
NOISE-CON 2004 the Impact of A-Weighting Sound Pressure Level
Baltimore, Maryland NOISE-CON 2004 2004 July 12-14 The Impact of A-weighting Sound Pressure Level Measurements during the Evaluation of Noise Exposure Richard L. St. Pierre, Jr. RSP Acoustics Westminster, CO 80021 Daniel J. Maguire Cooper Standard Automotive Auburn, IN 46701 ABSTRACT Over the past 50 years, the A-weighted sound pressure level (dBA) has become the predominant measurement used in noise analysis. This is in spite of the fact that many studies have shown that the use of the A-weighting curve underestimates the role low frequency noise plays in loudness, annoyance, and speech intelligibility. The intentional de-emphasizing of low frequency noise content by A-weighting in studies can also lead to a misjudgment of the exposure risk of some physical and psychological effects that have been associated with low frequency noise. As a result of this reliance on dBA measurements, there is a lack of importance placed on minimizing low frequency noise. A review of the history of weighting curves as well as research into the problems associated with dBA measurements will be presented. Also, research relating to the effects of low frequency noise, including increased fatigue, reduced memory efficiency and increased risk of high blood pressure and heart ailments, will be analyzed. The result will show a need to develop and utilize other measures of sound that more accurately represent the potential risk to humans. 1. INTRODUCTION Since the 1930’s, there have been large advances in the ability to measure sound and understand its effects on humans. Despite this, a vast majority of acoustical measurements done today still use the methods originally developed 70 years ago. -
6. Units and Levels
NOISE CONTROL Units and Levels 6.1 6. UNITS AND LEVELS 6.1 LEVELS AND DECIBELS Human response to sound is roughly proportional to the logarithm of sound intensity. A logarithmic level (measured in decibels or dB), in Acoustics, Electrical Engineering, wherever, is always: Figure 6.1 Bell’s 1876 é power ù patent drawing of the 10log ê ú telephone 10 ëreference power û (dB) An increase in 1 dB is the minimum increment necessary for a noticeably louder sound. The decibel is 1/10 of a Bel, and was named by Bell Labs engineers in honor of Alexander Graham Bell, who in addition to inventing the telephone in 1876, was a speech therapist and elocution teacher. = W = −12 Sound power level: LW 101og10 Wref 10 watts Wref Sound intensity level: = I = −12 2 LI 10log10 I ref 10 watts / m I ref Sound pressure level (SPL): P 2 P = rms = rms = µ = 2 L p 10log10 2 20log10 Pref 20 Pa .00002 N / m Pref Pref Some important numbers and unit conversions: 1 Pa = SI unit for pressure = 1 N/m2 = 10µBar 1 psi = antiquated unit for the metricly challenged = 6894Pa kg ρc = characteristic impedance of air = 415 = 415 mks rayls (@20°C) s ⋅ m2 c= speed of sound in air = 343 m/sec (@20°C, 1 atm) J. S. Lamancusa Penn State 12/4/2000 NOISE CONTROL Units and Levels 6.2 How do dB’s relate to reality? Table 6.1 Sound pressure levels of various sources Sound Pressure Description of sound source Subjective Level (dB re 20 µPa) description 140 moon launch at 100m, artillery fire at gunner’s intolerable, position hazardous 120 ship’s engine room, rock concert in front and close to speakers 100 textile mill, press room with presses running, very noise punch press and wood planers at operator’s position 80 next to busy highway, shouting noisy 60 department store, restaurant, speech levels 40 quiet residential neighborhood, ambient level quiet 20 recording studio, ambient level very quiet 0 threshold of hearing for normal young people 6.2 COMBINING DECIBEL LEVELS Incoherent Sources Sound at a receiver is often the combination from two or more discrete sources. -
Sony F3 Operating Manual
4-276-626-11(1) Solid-State Memory Camcorder PMW-F3K PMW-F3L Operating Instructions Before operating the unit, please read this manual thoroughly and retain it for future reference. © 2011 Sony Corporation WARNING apparatus has been exposed to rain or moisture, does not operate normally, or has To reduce the risk of fire or electric shock, been dropped. do not expose this apparatus to rain or moisture. IMPORTANT To avoid electrical shock, do not open the The nameplate is located on the bottom. cabinet. Refer servicing to qualified personnel only. WARNING Excessive sound pressure from earphones Important Safety Instructions and headphones can cause hearing loss. In order to use this product safely, avoid • Read these instructions. prolonged listening at excessive sound • Keep these instructions. pressure levels. • Heed all warnings. • Follow all instructions. For the customers in the U.S.A. • Do not use this apparatus near water. This equipment has been tested and found to • Clean only with dry cloth. comply with the limits for a Class A digital • Do not block any ventilation openings. device, pursuant to Part 15 of the FCC Rules. Install in accordance with the These limits are designed to provide manufacturer's instructions. reasonable protection against harmful • Do not install near any heat sources such interference when the equipment is operated as radiators, heat registers, stoves, or other in a commercial environment. This apparatus (including amplifiers) that equipment generates, uses, and can radiate produce heat. radio frequency energy and, if not installed • Do not defeat the safety purpose of the and used in accordance with the instruction polarized or grounding-type plug. -
Model 426B02 In-Line ICP™ A-Weight Filter Installation
Model 426B02 In-line ICP™ A-weight Filter Installation and Operating Manual For assistance with the operation of this product, contact PCB Piezotronics, Inc. Toll-free: 800-828-8840 24-hour SensorLine: 716-684-0001 Fax: 716-684-0987 E-mail: [email protected] Web: www.pcb.com Repair and Maintenance Returning Equipment If factory repair is required, our representatives will PCB guarantees Total Customer Satisfaction through its provide you with a Return Material Authorization (RMA) “Lifetime Warranty Plus” on all Platinum Stock Products number, which we use to reference any information you sold by PCB and through its limited warranties on all other have already provided and expedite the repair process. PCB Stock, Standard and Special products. Due to the This number should be clearly marked on the outside of sophisticated nature of our sensors and associated all returned package(s) and on any packing list(s) instrumentation, field servicing and repair is not accompanying the shipment. recommended and, if attempted, will void the factory warranty. Contact Information Beyond routine calibration and battery replacements PCB Piezotronics, Inc. where applicable, our products require no user 3425 Walden Ave. maintenance. Clean electrical connectors, housings, and Depew, NY14043 USA mounting surfaces with solutions and techniques that will Toll-free: (800) 828-8840 not harm the material of construction. Observe caution 24-hour SensorLine: (716) 684-0001 when using liquids near devices that are not hermetically General inquiries: [email protected] sealed. Such devices should only be wiped with a Repair inquiries: [email protected] dampened cloth—never saturated or submerged. For a complete list of distributors, global offices and sales In the event that equipment becomes damaged or ceases representatives, visit our website, www.pcb.com. -
Sound Power Measurement What Is Sound, Sound Pressure and Sound Pressure Level?
www.dewesoft.com - Copyright © 2000 - 2021 Dewesoft d.o.o., all rights reserved. Sound power measurement What is Sound, Sound Pressure and Sound Pressure Level? Sound is actually a pressure wave - a vibration that propagates as a mechanical wave of pressure and displacement. Sound propagates through compressible media such as air, water, and solids as longitudinal waves and also as transverse waves in solids. The sound waves are generated by a sound source (vibrating diaphragm or a stereo speaker). The sound source creates vibrations in the surrounding medium. As the source continues to vibrate the medium, the vibrations propagate away from the source at the speed of sound and are forming the sound wave. At a fixed distance from the sound source, the pressure, velocity, and displacement of the medium vary in time. Compression Refraction Direction of travel Wavelength, λ Movement of air molecules Sound pressure Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a sound wave. In air the sound pressure can be measured using a microphone, and in water with a hydrophone. The SI unit for sound pressure p is the pascal (symbol: Pa). 1 Sound pressure level Sound pressure level (SPL) or sound level is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. It is measured in decibels (dB) above a standard reference level. The standard reference sound pressure in the air or other gases is 20 µPa, which is usually considered the threshold of human hearing (at 1 kHz). -
Guide for the Use of the International System of Units (SI)
Guide for the Use of the International System of Units (SI) m kg s cd SI mol K A NIST Special Publication 811 2008 Edition Ambler Thompson and Barry N. Taylor NIST Special Publication 811 2008 Edition Guide for the Use of the International System of Units (SI) Ambler Thompson Technology Services and Barry N. Taylor Physics Laboratory National Institute of Standards and Technology Gaithersburg, MD 20899 (Supersedes NIST Special Publication 811, 1995 Edition, April 1995) March 2008 U.S. Department of Commerce Carlos M. Gutierrez, Secretary National Institute of Standards and Technology James M. Turner, Acting Director National Institute of Standards and Technology Special Publication 811, 2008 Edition (Supersedes NIST Special Publication 811, April 1995 Edition) Natl. Inst. Stand. Technol. Spec. Publ. 811, 2008 Ed., 85 pages (March 2008; 2nd printing November 2008) CODEN: NSPUE3 Note on 2nd printing: This 2nd printing dated November 2008 of NIST SP811 corrects a number of minor typographical errors present in the 1st printing dated March 2008. Guide for the Use of the International System of Units (SI) Preface The International System of Units, universally abbreviated SI (from the French Le Système International d’Unités), is the modern metric system of measurement. Long the dominant measurement system used in science, the SI is becoming the dominant measurement system used in international commerce. The Omnibus Trade and Competitiveness Act of August 1988 [Public Law (PL) 100-418] changed the name of the National Bureau of Standards (NBS) to the National Institute of Standards and Technology (NIST) and gave to NIST the added task of helping U.S. -
Lumens and Loudness: Projector Noise in a Nutshell
Lumens and loudness: Projector noise in a nutshell Jackhammers tearing up the street outside; the In this white paper, we’re going to take a closer look at projector noise: what causes neighbor’s dog barking at squirrels; the hum of it, how to measure it, and how to keep it to a minimum. the refrigerator: noise is a fixture in our daily Why do projectors make noise? lives, and projectors are no exception. Like many high-tech devices, they depend on cooling There’s more than one source of projector noise, of course, but cooling fans are by systems that remove excess heat before it can far the major offender—and there’s no way around them. Especially projector bulbs cause permanent damage, and these systems give off a lot of heat. This warmth must be continuously removed or the projector will overheat, resulting in serious damage to the system. The fans that keep air unavoidably produce noise. flowing through the projector, removing heat before it can build to dangerous levels, make noise. Fans can’t help but make noise: they are designed to move air, and the movement of air is what makes sound. How much sound they make depends on their construction: the angle of the blades, their size, number and spacing, their surface quality, and the fan’s rotational speed. Moreover, for projector manufacturers it’s also key not to place a fan too close to an air vent or any kind of mesh, or they’ll end up with the siren effect: very annoying high-frequency, pure-tone noise caused by the sudden interruption of the air flow by the vent bars or the mesh wires. -
Audio Loudness—Or Why Commercials Can Be Annoying
Telestream Whitepaper Audio loudness—or why commercials can be annoying “Audio loudness is one of the most Overview common causes of complaints to You are sitting there quietly watching your favorite show on TV when all of a broadcasters. So much so that it is sudden the commercial comes on – BAM, WAM, BUY, BUY ... screams at being increasingly subjected to you. The purpose of the commercial is to grab your attention in the few legislation in many countries seconds of the spot. The recording engineers in the commercials production including North America, UK, agency will turn up the sound levels into the red for maximum impact and Europe and Australia.“ effect to shake you out of your slumbers. However, the effect can be to intensely annoy the viewer who reaches for the channel change, or worse, calls the TV company to complain. Audio loudness is one of the most common causes of complaints to broad- casters. So much so that it is being increasingly subjected to legislation in many countries including North America, UK, Europe and Australia. The US ‘Commercial Advertisement Loudness Mitigation Act’ (CALM) seeks to require the Federal Communications Commission to regulate the audio of commer- cials from being broadcast at louder volumes than the program material they accompany. The EBU in Europe have issued R128 loudness recommenda- tions. So how can broadcasters control the levels of commercials they receive so that loudness levels are consistent from program to commercial to trailer to program? They could play out every commercial and program, to subjectively listen to them, adjust or turn down the levels and re-encode the file, but this is usually impractical and loudness is not the same as levels. -
Solid-State Memory Camcorder
4-425-717-13(3) Solid-State Memory Camcorder PMW-200 PMW-100 Operating Instructions Before operating the unit, please read this manual thoroughly and retain it for future reference. © 2012 Sony Corporation WARNING • Refer all servicing to qualified service personnel. Servicing is required when the To reduce the risk of fire or electric shock, apparatus has been damaged in any way, do not expose this apparatus to rain or such as power-supply cord or plug is moisture. damaged, liquid has been spilled or objects To avoid electrical shock, do not open the have fallen into the apparatus, the apparatus cabinet. Refer servicing to qualified has been exposed to rain or moisture, does personnel only. not operate normally, or has been dropped. WARNING Do not install the appliance in a confined When installing the unit, incorporate a readily space, such as book case or built-in cabinet. accessible disconnect device in the fixed wiring, or connect the power plug to an easily IMPORTANT accessible socket-outlet near the unit. If a fault The nameplate is located on the bottom. should occur during operation of the unit, WARNING operate the disconnect device to switch the Excessive sound pressure from earphones power supply off, or disconnect the power plug. and headphones can cause hearing loss. In order to use this product safely, avoid Important Safety Instructions prolonged listening at excessive sound • Read these instructions. pressure levels. • Keep these instructions. • Heed all warnings. For the customers in the U.S.A. • Follow all instructions. This equipment has been tested and found to • Do not use this apparatus near water. -
The Human Ear Hearing, Sound Intensity and Loudness Levels
UIUC Physics 406 Acoustical Physics of Music The Human Ear Hearing, Sound Intensity and Loudness Levels We’ve been discussing the generation of sounds, so now we’ll discuss the perception of sounds. Human Senses: The astounding ~ 4 billion year evolution of living organisms on this planet, from the earliest single-cell life form(s) to the present day, with our current abilities to hear / see / smell / taste / feel / etc. – all are the result of the evolutionary forces of nature associated with “survival of the fittest” – i.e. it is evolutionarily{very} beneficial for us to be able to hear/perceive the natural sounds that do exist in the environment – it helps us to locate/find food/keep from becoming food, etc., just as vision/sight enables us to perceive objects in our 3-D environment, the ability to move /locomote through the environment enhances our ability to find food/keep from becoming food; Our sense of balance, via a stereo-pair (!) of semi-circular canals (= inertial guidance system!) helps us respond to 3-D inertial forces (e.g. gravity) and maintain our balance/avoid injury, etc. Our sense of taste & smell warn us of things that are bad to eat and/or breathe… Human Perception of Sound: * The human ear responds to disturbances/temporal variations in pressure. Amazingly sensitive! It has more than 6 orders of magnitude in dynamic range of pressure sensitivity (12 orders of magnitude in sound intensity, I p2) and 3 orders of magnitude in frequency (20 Hz – 20 KHz)! * Existence of 2 ears (stereo!) greatly enhances 3-D localization of sounds, and also the determination of pitch (i.e. -
Perceptual Loss Function for Neural Modelling of Audio Systems
PERCEPTUAL LOSS FUNCTION FOR NEURAL MODELLING OF AUDIO SYSTEMS Alec Wright and Vesa Valim¨ aki¨ ∗ Acoustics Lab, Dept. Signal Processing and Acoustics, Aalto University, FI-02150 Espoo, Finland alec.wright@aalto.fi ABSTRACT WaveNet-style model [11, 12], as well as RNNs [13, 14] and This work investigates alternate pre-emphasis filters used as a hybrid model, which combined a convolutional layer with error- part of the loss function during neural network training for an RNN [15]. In our previous work [11, 12, 14] the to-signal ratio nonlinear audio processing. In our previous work, the error- (ESR) loss function was used during network pre-emphasis to-signal ratio loss function was used during network training, training, with a first-order highpass filter being with a first-order highpass pre-emphasis filter applied to both used to suppress the low frequency content of both the target the target signal and neural network output. This work con- signal and neural network output. siders more perceptually relevant pre-emphasis filters, which In this work we investigate the use of alternate pre- include lowpass filtering at high frequencies. We conducted emphasis filters in the training of a neural network consisting listening tests to determine whether they offer an improve- of a Long Short-Term Memory (LSTM) and a fully connected ment to the quality of a neural network model of a guitar tube layer. We have conducted listening tests to determine whether amplifier. Listening test results indicate that the use of an the novel loss functions offer an improvement to the quality A-weighting pre-emphasis filter offers the best improvement of the resulting model.