Download or read book The Hazard of Exposure to Impulse Noise as a Function of Frequency written by and published by . This book was released on 1991 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: The energy spectrum of a noise is known to be an important variable in determining the effects of a traumatic exposure. However, existing criteria for exposure to impulse noise do not consider the frequency spectrum of an impulse as a variable in the evaluation of the hazards to the auditory system. This report presents the results of a study that was designed to determine the relative potential that impulsive energy concentrated at different frequencies has in causing auditory system trauma. One hundred and eighteen (118) chinchilla, divided into 20 groups with 5 to 7 animals per group, were used in these experiments. Pre- and post-exposure hearing thresholds were measured at 10 test frequencies between 0.125 and 8 kHz on each animal using avoidance conditioning procedures. Quantitative histology (cochleograms) was used to determine the extent and pattern of the sensory cell damage. The noise exposure stimuli consisted of six different computer-generated narrow band tone bursts having center frequencies located at 0.260, 0.775, 1.350, 2.450, and 3.550 kHz. Each narrow band exposure stimulus was presented at two to four different intensities. An analysis of the audiometric and histological data allowed frequency weighing functions to be derived.
Download or read book An Experimental Basis for the Estimation of Auditory System Hazard Following Exposure to Impulse Noise written by and published by . This book was released on 1992 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The energy spectrum of a noise is known to be an important effects of a traumatic exposure. However, existing criteria for exposure to impulse noise do not consider the frequency spectrum of an impulse as a variable in the evaluation of the hazards to the auditory system. This report presents the results of three studies that were designed to determine the relative potential that impulsive energy has in causing auditory system trauma. Four hundred and seventy five (475) chinchilla were used in these experiments. Pre- and post- exposure hearing thresholds were measured on each subject. In the first study, the noise exposure stimuli consisted of six different computer-generated narrow band tone bursts having center frequencies located at 0.260, 0.775, 1.025, 1. 350, 2.450, and 3.550 kHz. Each narrow band exposure stimulus was presented at two to four different intensities. An analysis of the audiometric data allowed a frequency weighting function to be derived. This weighting function de- emphasizes low frequency energy more than the conventional A-weighting function. In the second study, the exposures consisted of two--types of broad band computer synthesized impulses. Subjects were exposed to 100 impulses at a rate of 1-per-3-seconds. Each type of impulse was presented at 3 intensities. The third study used impulses generated by three different diameter shock tubes. Subjects were exposed to 1, 10, or 100 impulses at one of three intensities. The results of the second and third studies were interpreted using the weighting' function derived from the first study. The hearing loss from all three studies is a linear function of the weighted SEL calculated using the weighting function, derived in the first study. Impulse noise, Hearing, Chinchilla, Audiometry and histology.
Download or read book Characterization of Impulse Noise and Hazard Analysis of Impulse Noise Induced Hearing Loss Using AHAAH Modeling written by Qing Wu (‡e author) and published by . This book was released on 2014 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Millions of people across the world are suffering from noise induced hearing loss (NIHL), especially under working conditions of either continuous Gaussian or non-Gaussian noise that might affect human's hearing function. Impulse noise is a typical non-Gaussian noise exposure in military and industry, and generates severe hearing loss problem. This study mainly focuses on characterization of impulse noise using digital signal analysis method and prediction of the auditory hazard of impulse noise induced hearing loss by the Auditory Hazard Assessment Algorithm for Humans (AHAAH) modeling. A digital noise exposure system has been developed to produce impulse noises with peak sound pressure level (SPL) up to 160 dB. The characterization of impulse noise generated by the system has been investigated and analyzed in both time and frequency domains. Furthermore, the effects of key parameters of impulse noise on auditory risk unit (ARU) are investigated using both simulated and experimental measured impulse noise signals in the AHAAH model. The results showed that the ARUs increased monotonically with the peak pressure (both P + and P- ) increasing. With increasing of the time duration, the ARUs increased first and then decreased, and the peak of ARUs appeared at about t = 0.2 ms (for both t+ and t- ). In addition, the auditory hazard of experimental measured impulse noises signals demonstrated a monotonically increasing relationship between ARUs and system voltages.
Download or read book Characterization of Impulse Noise and Hazard Analysis of Impulse Noise Induced Hearing Loss Using AHAAH Modeling written by Qing Wu and published by . This book was released on 2014 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Millions of people across the world are suffering from noise induced hearing loss (NIHL), especially under working conditions of either continuous Gaussian or non-Gaussian noise that might affect human's hearing function. Impulse noise is a typical non-Gaussian noise exposure in military and industry, and generates severe hearing loss problem. This study mainly focuses on characterization of impulse noise using digital signal analysis method and prediction of the auditory hazard of impulse noise induced hearing loss by the Auditory Hazard Assessment Algorithm for Humans (AHAAH) modeling. A digital noise exposure system has been developed to produce impulse noises with peak sound pressure level (SPL) up to 160 dB. The characterization of impulse noise generated by the system has been investigated and analyzed in both time and frequency domains. Furthermore, the effects of key parameters of impulse noise on auditory risk unit (ARU) are investigated using both simulated and experimental measured impulse noise signals in the AHAAH model. The results showed that the ARUs increased monotonically with the peak pressure (both P + and P- ) increasing. With increasing of the time duration, the ARUs increased first and then decreased, and the peak of ARUs appeared at about t = 0.2 ms (for both t+ and t- ). In addition, the auditory hazard of experimental measured impulse noises signals demonstrated a monotonically increasing relationship between ARUs and system voltages.
Download or read book Frequency Dependence of Impulse Noise Attenuation written by James H. Patterson (Jr.) and published by . This book was released on 1977 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Attempts have been made to use a single auditory value of attenuation to assess the hazard to hearing from exposure to high intensity impulse noise and to establish maximum allowable impulse noise exposure levels. This procedure ignores the interaction of the attenuation characteristics of the hearing protector and the energy density spectrum of the impulse. This report demonstrated that errors as large as 17 dB can result from failing to account for this interaction. (Author).
Download or read book Noise and Military Service written by Institute of Medicine and published by National Academies Press. This book was released on 2006-01-20 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Institute of Medicine carried out a study mandated by Congress and sponsored by the Department of Veterans Affairs to provide an assessment of several issues related to noise-induced hearing loss and tinnitus associated with service in the Armed Forces since World War II. The resulting book, Noise and Military Service: Implications for Hearing Loss and Tinnitus, presents findings on the presence of hazardous noise in military settings, levels of noise exposure necessary to cause hearing loss or tinnitus, risk factors for noise-induced hearing loss and tinnitus, the timing of the effects of noise exposure on hearing, and the adequacy of military hearing conservation programs and audiometric testing. The book stresses the importance of conducting hearing tests (audiograms) at the beginning and end of military service for all military personnel and recommends several steps aimed at improving the military services' prevention of and surveillance for hearing loss and tinnitus. The book also identifies research needs, emphasizing topics specifically related to military service.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technology for a Quieter America written by National Academy of Engineering and published by National Academies Press. This book was released on 2010-10-30 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exposure to noise at home, at work, while traveling, and during leisure activities is a fact of life for all Americans. At times noise can be loud enough to damage hearing, and at lower levels it can disrupt normal living, affect sleep patterns, affect our ability to concentrate at work, interfere with outdoor recreational activities, and, in some cases, interfere with communications and even cause accidents. Clearly, exposure to excessive noise can affect our quality of life. As the population of the United States and, indeed, the world increases and developing countries become more industrialized, problems of noise are likely to become more pervasive and lower the quality of life for everyone. Efforts to manage noise exposures, to design quieter buildings, products, equipment, and transportation vehicles, and to provide a regulatory environment that facilitates adequate, cost-effective, sustainable noise controls require our immediate attention. Technology for a Quieter America looks at the most commonly identified sources of noise, how they are characterized, and efforts that have been made to reduce noise emissions and experiences. The book also reviews the standards and regulations that govern noise levels and the federal, state, and local agencies that regulate noise for the benefit, safety, and wellness of society at large. In addition, it presents the cost-benefit trade-offs between efforts to mitigate noise and the improvements they achieve, information sources available to the public on the dimensions of noise problems and their mitigation, and the need to educate professionals who can deal with these issues. Noise emissions are an issue in industry, in communities, in buildings, and during leisure activities. As such, Technology for a Quieter America will appeal to a wide range of stakeholders: the engineering community; the public; government at the federal, state, and local levels; private industry; labor unions; and nonprofit organizations. Implementation of the recommendations in Technology for a Quieter America will result in reduction of the noise levels to which Americans are exposed and will improve the ability of American industry to compete in world markets paying increasing attention to the noise emissions of products.
Download or read book The Noise Manual written by Elliott H. Berger and published by AIHA. This book was released on 2003 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topics covered include fundamentals of sound, vibration and hearing, elements of a hearing conservation program, noise interference and annoyance, regulations, standards and laws.
Download or read book Occupational Noise Exposure written by Department of Health and Human Services and published by Createspace Independent Publishing Platform. This book was released on 2014-02-19 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Occupational Safety and Health Act of 1970, Congress declared that its purpose was to assure, so far as possible, safe and healthful working conditions for every working man and woman and to preserve our human resources. In this Act, the National Institute for Occupational Safety and Health (NIOSH) is charged with recommending occupational safety and health standards and describing exposure concentrations that are safe for various periods of employment-including but not limited to concentrations at which no worker will suffer diminished health, functional capacity, or life expectancy as a result of his or her work experience. By means of criteria documents, NIOSH communicates these recommended standards to regulatory agencies (including the Occupational Safety and Health Administration [OSHA]) and to others in the occupational safety and health community. Criteria documents provide the scientific basis for new occupational safety and health standards. These documents generally contain a critical review of the scientific and technical information available on the prevalence of hazards, the existence of safety and health risks, and the adequacy of control methods. In addition to transmitting these documents to the Department of Labor, NIOSH also distributes them to health professionals in academic institutions, industry, organized labor, public interest groups, and other government agencies. In 1972, NIOSH published Criteria for a Recommended Standard: Occupational Exposure to Noise, which provided the basis for a recommended standard to reduce the risk of developing permanent hearing loss as a result of occupational noise exposure [NIOSH 1972]. NIOSH has now evaluated the latest scientific information and has revised some of its previous recommendations. The 1998 recommendations go beyond attempting to conserve hearing by focusing on preventing occupational noise-induced hearing loss (NIHL). This criteria document reevaluates and reaffirms the recommended exposure limit (REL) for occupational noise exposure established by the National Institute for Occupational Safety and Health (NIOSH) in 1972. The REL is 85 decibels, A-weighted, as an 8-hr time-weighted average (85 dBA as an 8-hr TWA). Exposures at or above this level are hazardous. By incorporating the 4000-Hz audiometric frequency into the definition of hearing impairment in the risk assessment, NIOSH has found an 8% excess risk of developing occupational noise-induced hearing loss (NIHL) during a 40-year lifetime exposure at the 85-dBA REL. NIOSH has also found that scientific evidence supports the use of a 3-dB exchange rate for the calculation of TWA exposures to noise. The recommendations in this document go beyond attempts to conserve hearing by focusing on prevention of occupational NIHL. For workers whose noise exposures equal or exceed 85 dBA, NIOSH recommends a hearing loss prevention program (HLPP) that includes exposure assessment, engineering and administrative controls, proper use of hearing protectors, audiometric evaluation, education and motivation, recordkeeping, and program audits and evaluations. Audiometric evaluation is an important component of an HLPP. To provide early identification of workers with increasing hearing loss, NIOSH has revised the criterion for significant threshold shift to an increase of 15 dB in the hearing threshold level (HTL) at 500, 1000, 2000, 3000, 4000, or 6000 Hz in either ear, as determined by two consecutive tests. To permit timely intervention and prevent further hearing losses in workers whose HTLs have increased because of occupational noise exposure, NIOSH no longer recommends age correction on individual audiograms.
Download or read book The Role of Peak Pressure in Determining the Auditory Hazard of Impulse Noise written by James H. Patterson (Jr.) and published by . This book was released on 1986 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most current Damage Risk Criteria (DRC) for human exposure to impulse noise are written in terms of peak pressure as the primary index of the traumatic potential or hazard associated with exposure to an impulse noise. Since the peak pressure is only one of many parameters of an impulse, there is a question whether or not a DRC based on peak pressure can reflect accurately the hazard to hearing posed by impulse noise. The experiments described in this report were designed to determine whether peak pressure is an adequate quantifier for an impulse noise DRC. The general approach was to construct two types of impulse noise with the same Fourier pressure spectrum, but with different peak pressures. This makes it possible to compare the hearing loss and injury resulting from impulses which have the same total energy distributed the same way across frequency, but with different peak pressures. The threshold shift measured during the first few hours after exposure showed systematic variation with both peak pressure and energy level. The permanent threshold shift (20 to 30 days postexposure) and the loss of sensory cells showed strong dependence on energy level, with a less pronounced dependence on peak pressure. These results indicate that peak pressure is not a sufficient indicator of auditory hazard; however, energy alone is not a sufficient indicator either. Keywords: Exposure (Physiology), Impulse noise.
Download or read book Hazardous Exposure to Impulse Noise written by and published by . This book was released on 1992 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Limits for exposure to hazardous agents are set by defining some specific acceptable effect (the response) and then determining what exposure conditions (the dose) produce that effect. In 1968, the Committee on Hearing, Bioacoustics, and Biomechanics (CHABA) proposed a limit for exposure to impulse noise (gunfire) in which the response was a specific amount of temporary threshold shift (TTS) and dose was specified in terms of the peak pressure and two aspects of the duration of a particular impulse, with correction factors for number of impulses and for the angle of incidence on the ear. The proposal was basically an endorsement of one advanced by an Anglo-American team of investigators (Coles, Garinther, Hodge, and Rice, 1968) that was based on the very limited pool of information then available about the auditory hazard of gunfire. Coles, Garinther, and Hodge were members of the Working Group on Proposed Damage-Risk Criterion for Impulse Noise (Gunfire).
Download or read book Hazard from an Intense Midrange Impulse written by and published by . This book was released on 1989 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been hypothesized that the ear would become increasingly susceptible to impulses (gunfire) as the spectral peak of the impulse approached the frequency region where the ear was tuned best (about 4 kHz for the cat ear) (G.R. Price, J. Acoust. Soc. Am. Suppl. 1 62, S95 (1977)). This prediction was counter to the predictions of the world's damage-risk criteria for impulse noise. It has been supported by experiments using exposures to 100-Hz and 800- to 1000-Hz impulses; but no test had been run at the point of predicted maximum susceptibility. In the present experiment, three groups of cats were exposed to 50 impulses produced by a primer explosion (spectral peak at 4 kHz) at peak levels of 135, 140, or 145 dB. Auditory thresholds were electrophysiologically measured from the vertex to 2-, 4-, 8-, and 16-kHz tone pips and losses were determined 30 min after exposure and more than 2 months post-exposure. Losses were greatest at 4 kHz, began to develop at 134-dB peak pressure, and the immediate losses grew at a rate of about 7 dB for every dB increase in peak pressure. About half of the loss measured immediately became permanent. The energy required to begin producing a permanent threshold shift was only about 0. 07 J/m squared, far lower than that required with continuous noises at lower sound pressures. The data were interpreted as supporting the original hypothesis of greater susceptibility in the midrange.
Download or read book Use of Animal Test Data in the Development of a Human Auditory Hazard Criterion for Impulse Noise Part 1 written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hearing loss and sensory cell loss data, obtained from 909 chinchillas exposed to one of 137 different impulse noise or blast wave exposure paradigms, were statistically analyzed. The objective was to extract relations between the effects of the exposure on the auditory system (effects metrics) and metrics used to characterize the blast wave exposure. Specifically the following two questions were asked: (a) What is the best indicator of the amount of hazard associated with an impulse noise exposure? (b) How does the hazard of an impulse noise exposure accumulate with increasing numbers of impulses? Two analytical approaches were used. Both approaches indicated that the P-weighting functions or one of its derivatives (P1-, P2- or R-weighting) best organized the effects metrics. Depending on the analytical approach, either an energy trading rule of 10 log(10) N or 6 log(10) N; where N is the number of impulses, best organized the data for N between 10 and 100. For exposures of between 1 and 10 impulses, a region of the parametric space that is of considerable practical significance, there is insufficient data to form any conclusions. For this region the limited data suggest that an energy trading rule i.e., 10 log N, does not work.
Download or read book Traditional Rating of Noise Versus Physiological Costs of Sound Exposures to the Hearing written by H. Strasser and published by IOS Press. This book was released on 2005-09-08 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: In occupational safety and health acts, ordinances, regulations, directives, standards and guidelines, A-weighted sound exposures, varying in level and duration, are traditionally converted to an 8-hour-average sound level by applying the 3-dB exchange rate. Under the prerequisite that the energy equivalent rating level does not exceed 85 dB(A)/8 h, even impulse noise exposures of up to 140 dB are declared harmless. Indeed, the mutual settlement of level and duration based on the concept of energy equivalence is correct as far as sound energy or physical dose is concerned. However, between this principle and work physiological and work psychological, i.e. ergonomics paradigms, some decisive discrepancies do exist. People react to exposures according to human characteristics rather than 'function' according to the laws of physics as they apply to inert matter. This has been demonstrated by a series of new experimental approaches, in which temporary threshold shifts and their restitution associated with various energy equivalent noise exposures have been measured. Also the impact of various types of loud music has been investigated. In addition to the conventionally determined maximum threshold shift, TTS2, and the time it takes to reach the resting hearing level again, the area under the restitution curve, indicate the total physiological costs the hearing has to pay for a preceding sound exposure. This book is an attempt to increase the transparency in existing evaluation methods and – in the interest of pertinent disclosure of risks associated with common procedures – to work towards the elimination of unacceptable simplifications and dangerously erroneous assessments.
Download or read book The Effects of Blast Trauma Impulse Noise on Hearing A Parametric Study written by and published by . This book was released on 1988 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are three broad goals to this project. The first and primary goal is to begin the systematic development of a data base from which one could estimate the hazards to hearing resulting from exposure to blast waves or other high level impulse noise transients. To achieve this primary objective the following two objectives must first be achieved: (1) to develop a methodology to efficiently acquire data on a large number of experimental animals that have been exposed to a variety variables; (2) to develop a set of blast wave simulation devices which can reliably generate blast waves with a variable distribution of spectral energy in a laboratory environment. This report will describe progress that was achieved on each of these objectives. The evaluation of hearing consisted of pre- and postexposure measurements of pure tone thresholds and tuning curves (masked thresholds). Quantitative and qualitative preparation technique. Keywords: Physiological effects; Stress physiology; Hearing ; Blast waves; Exposure physiology; Tables data.
Download or read book A Health Hazard Assessment for Blast Overpressure Exposures Subtitle Use of Animal Test Data in the Development of a Human Auditory Hazard Criterion for Impulse Noise Part 1 written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hearing loss and sensory cell loss data, obtained from 909 chinchillas exposed to one of 137 different impulse noise or blast wave exposure paradigms, were statistically analyzed. The objective was to extract relations between the effects of the exposure on the auditory system (effects metrics) and metrics used to characterize the blast wave exposure. Specifically the following two questions were asked: (a) What is the best indicator of the amount of hazard associated with an impulse noise exposure? (b) How does the hazard of an impulse noise exposure accumulate with increasing numbers of impulses? Two analytical approaches were used. Both approaches indicated that the P-weighting functions or one of its derivatives (P1-, P2- or R-weighting) best organized the effects metrics. Depending on the analytical approach, either an energy trading rule of 10 log10 N or 6 log10 N; where N is the number of impulses, best organized the data for N between 10 and 100. For exposures of between 1 and 10 impulses, a region of the parametric space that is of considerable practical significance, there is insufficient data to form any conclusions. For this region the limited data suggest that an energy trading rule i.e., 10 log N, does not work.
