Download or read book The Effects of Reverberant Blast Trauma Impulse Noise on Hearing Parametric Studies written by and published by . This book was released on 1994 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of exposure to high levels of reverberant blast waves (impulse noise) on the auditory system using an animal (chinchilla) model are reported. Blast waves were generated by two different shock tubes which produced wave signatures having different spectral distributions of energy. Intensities for each blast wave source were 150, 155, and 160 dB peak SPL with exposure to 1, 10, or 100 impulses. Repetition rates were fixed at one impulse/sec. There were 15 subjects per group. Brainstem evoked potentials were used to estimate temporary and permanent threshold shifts and conventional surface preparations of the cochlea were used to quantitatively assess sensory cell loss. In addition, pre and postexposure cubic distortion product otoacoustic emissions (3DPE) were collected on a subset of these animals for correlation with audiometric and histological indices of trauma. Trauma systematically increased with sound exposure level (SEL) and was dependent on the energy spectrum of the impulse. An application of the A and P weighting functions to the spectra improved the correlations between indices of trauma and SEL. The 3DPE data were consistent with PTS and, overall, both measures were correlated with sensory cell loss. (AN).
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 1991 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary goal of this research project was to produce a data base from which one could estimate the hazards to hearing associated with a wide variety of non-reverberant (free-field) blast were exposures. To achieve this objective four different blast wave generation devices were designed. Three of these sources are based upon shock tube methods and one uses a high energy electrical discharge to produce a shock wave. The four sources produce pressure- time waveforms whose A-weighted amplitude spectra peak at four different regions of the audible spectrum. The conventional shock tube (Source I) has maximum A- weighted energy in the 0.250 kHz octave band; the 5-inch Lamont rapid acting valve driven shock tube (Source II) has its energy maxima in the 2 kHz octave band; while the spark discharge energy (Source III) has its energy maxima in the 2 kHz octave band; while the spark discharge energy (Source IV) is concentrated in the 4 and 8 kHz octave band. These sources in anechoic surroundings produce non-reverberant waves that approximate the ideal Friedlander wave.
Download or read book The Effects of Reverberant Impulse Noise BLAST WAVES on Hearing Parametric Studies written by Roger P. Hamernik and published by . This book was released on 1993 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research is directed at studying the effects on the auditory system of exposure to high levels of reverberant impulse noise using an animal (chinchilla) model. The blast waves were generated by a three inch diameter shock tube (source III), which produced wave signatures having spectral energy concentrated in the 12 kHz region. The waves were discharged into a reverberant chamber within which animals were individually exposed. Animals were exposed to either 150, 155 or 160 dB peak SPL impulses. The number of impulses presented at each intensity was 1, 10 or 100, with repetition rates fixed at 1 impulse/sec. This parametric design yielded 9 groups of animals. There were 15 animals in each group. Brainstem evoked potentials were used to estimate temporary and permanent threshold shifts and conventional surface preparations of the cochlea were used to quantitatively assess sensory cell loss. This midterm report presents the audiometric data and a portion of the histological data for the 136 animals that completed the exposure protocol. The audiometric and available histological data showed that damage to the auditory system systematically increased as the energy of the exposure was increased through manipulation of number of presentations or peak SPL. Hearing loss, Impulse noise, Blast waves, RADIII.
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 246 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 database 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 an 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 data on each experimental cochlea was obtained from the traditional surface preparation technique. Keywords: Physiological effects; Stress physiology; Hearing; Blast waves; Exposure physiology; Tables data.
Download or read book The Effects of Blast Trauma Impulse Noise on Hearing A Parametric Study Part 2 written by and published by . This book was released on 1988 with total page 211 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 The Effects of Blast Trauma Impulse Noise on Hearing A Parametric Study Source II written by and published by . This book was released on 1989 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are three broad goals to this contract. The first and primary goal is to study the effects of high level blast wave exposure on the conductive and sensory structures of the mammalian ear. This includes the use of the auditory evoked potential to measure hearing thresholds and tuning curves prior to and after exposure to various blast wave exposures. Parameters of the blast waves studied include intensity, spectral composition, number of impulses and repetition rate. Correlations among hearing measures, exposure variables and histology have been developed. To achieve the above, the following two objectives must be completed: 1) develop a series of blast wave generation devices which are suitable for the laboratory simulation of a wide spectrum of blast waves; and develop a suitable set of software and a PC-based computer system which will interact with crystal and capacitive microphones to capture and analyze blast waves. Four sources have been developed along with the specified analysis system. The results from the Source I (a conventional shock tube) were summarized in reports ADA 206-180 and ADA 203-854. This report summaries the results from Source II, a 5-inch Lamont valve-driven shock tube.
Download or read book The Effects of Blast Trauma Impulse Noise on Hearing A Parametric Study Source III written by and published by . This book was released on 1990 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are three broad goals to this contract. The first and primary goal is to study the effects of high level blast wave exposure on the conductive and sensory structures of the mammalian ear. This includes the use of the auditory evoked potential to measure hearing thresholds and tuning curves prior to and after exposure to various blast wave exposures. Parameters of the blast waves studied include intensity, spectral composition, number of impulses and repetition rate. Correlations among hearing measures, exposure variables and histology have been developed. To achieve the above, the following two secondary objectives had to be completed: (1) develop a series of blast wave generation devices which are suitable for the laboratory simulation of a wide spectrum of blast waves; and (2) develop a suitable set of software and a PC-based computer system which can interact with crystal and capacitive microphones to capture and analyze blast waves.
Download or read book The Effects of Blast Trauma Impulse Noise on Hearing A Parametric Study Source IV written by and published by . This book was released on 1991 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first and primary goal of this contract is to study the effects of high level blast wave exposure on the conductive and sensory structures of the mammalian ear. This includes the use of the auditory evoked potential to measure hearing thresholds and tuning curves prior to and after exposure to various blast waves. Parameters of the blast waves studied include intensity, spectral composition, number of impulses and repetition rate. Correlations among hearing measures, exposure variables and histology have been developed. To achieve the above, two secondary objectives had to be completed: (1) develop a series of blast wave generation devices which are suitable for the laboratory simulation of a wide variety of blast waves; and (2) develop a suitable set of software and a PC-based computer system which can interact with crystal and capacitive microphones to capture and analyze blast waves. Four blast wave sources have been developed along with an analysis system. The results from Source I were summarized in reports ADA 206-180 and ADA 203-854. Source II results were summarized in report ADA 221-731 while Source III results were summarized in report ADA 228-368. This report summarizes the results from Source IV, an electrical spark discharge device which generates a blast wave in anechoic (free-field) surroundings whose peak of the A-weighted energy spectrum is in the 4kHz octave band.
Download or read book Effects of Noise and Blasts written by Hans M. Borchgrevink and published by . This book was released on 1991 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Blast Trauma The Effect on Hearing written by Roger P. Hamernik and published by . This book was released on 1983 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research was to study the effects of impulse noise (blast trauma) on auditory function. The impulse noise was produced by a compressed air-driven shock tube; the exposures were varied to produce a range of cochlear lesions. The effects of impulse noise was studied by measuring: 1) changes in pure tone thresholds and tuning curves obtained behaviorally or with the auditory evoked response, 2) changes in the thresholds and tuning curves of single auditory nerve fibers, 3) changes in cochlear anatomy as determined by light and electron microscopy. The goal of the study was to relate the audiometric and physiological data with the cochlear pathologies in order to understand the nature of auditory pathologies produced by exposure to blast waves. Keywords: Hearing loss; Hair cells; and Evoked response.
Download or read book Blast Trauma The Effects on Hearing written by R. P. Hamernik and published by . This book was released on 1981 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project will determine what effects impulse noise (blast trauma) has on hearing performance, the response patterns of auditory nerve fibers and the morphology of cochlea. Initially, audiograms and psychophysical tuning curves of the normal chinchilla will be measured; then the animals will be exposed to impulse noise. Afterwards, the psychophysical measures will be repeated in order to evaluate the changes in hearing performance. Microelectrode techniques will be used to sample the thresholds and tuning curves of single VIII nerve fibers and the neural results will then be compared with the behavioral data. Finally, the cochleas of the noise exposed animals will be embedded in plastic ans dissected out for light and electron microscopic analysis; cochleograms will be prepared and damage to cilia.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 1556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1996 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Health Hazard Assessment for Blast Overpressure Exposures Subtitle Evaluation of Impulse Noise Criteria Using Human Volunteer Data written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The evaluation of impulse noise criteria is becoming more critical as many new weapons exceed exposure levels for single hearing protection set forth by the MIL-STD-1474D. Previous man-rating studies have consistently shown that auditory injury does not occur at these levels. Consequently, there is general belief that the current standards under predict the threshold at which injury occurs. Four impulse noise auditory injury criteria adopted by NATO countries, namely, the MIL-STD-1474D (USA), Pfander (Germany), Smoorenburg (Netherlands), and L(Aeq8) (France), are evaluated against human volunteer data. Four data sets from subjects wearing single hearing protection exposed to increasing blast overpressure effects were obtained from tests sponsored by the US Army Medical Research and Materiel Command. Two data sets were obtained from free field and bunker tests using RACAL earmuffs modified to simulate poor fitting. Two other data sets came from the M198 howitzer and Viper man-rating studies using EAR earplugs. Injury threshold was taken as a temporary threshold shift (TTS)>/- 25 ("3 at any frequency. Using logistic regression, the four criteria were each correlated with the test data. The analysis shows that all four criteria are overly conservative by 4-12 ("3. The MIL-STD-1474D for single hearing protection is 9.9).
Download or read book Government Reports Annual Index written by and published by . This book was released on 1994 with total page 1692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Perspectives on Noise induced Hearing Loss written by Roger P. Hamernik and published by Lippincott Williams & Wilkins. This book was released on 1982 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Information on Levels of Environmental Noise Requisite to Protect Public Health and Welfare with an Adequate Margin of Safety written by United States. Office of Noise Abatement and Control and published by . This book was released on 1974 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
