Search NASA⌕ Search

SEARCH · Search NASA

Results for “HEARING”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Use of negotiated rulemaking in developing technical rules for low-Earth orbit mobile satellite systems

Technical innovations have converged with the exploding market demand for mobile telecommunications to create the impetus for low-earth orbit (LEO) communications satellite systems. The so-called 'Little LEO's' propose use of VHF and UHF spectrum to provide position - location and data messaging services. The so-called 'Big LEO's' propose to utilize the RDSS bands to provide voice and data services. In the United States, several applications were filed with the U.S. Federal Communications Commission (FCC) to construct and operate these mobile satellite systems. To enable the prompt introduction of such new technology services, the FCC is using innovative approaches to process the applications. Traditionally, when the FCC is faced with 'mutually exclusive' applications, e.g. a grant of one would preclude a grant of the others, it uses selection mechanisms such as comparative hearings or lotteries. In the case of the LEO systems, the FCC has sought to avoid these time-consuming approaches by using negotiated rulemakings. The FCC's objective is to enable the multiple applicants and other interested parties to agree on technical and service rules which will enable the grant of all qualified applications. With regard to the VHF/UHF systems, the Advisory Committee submitted a consensus report to the FCC. The process for the systems operating in the bands above 1 GHz involved more parties and more issues but still provided the FCC useful technical information to guide the adoption of rules for the new mobile satellite service.

Taylor, Leslie A.↗
NASA NTRS1994

Comparison of methods of predicting community response to impulsive and nonimpulsive noise

Several scientific, regulatory, and policy-coordinating bodies have developed methods for predicting community response to sonic booms. The best known of these is the dosage-response relationship of Working Group 84 of the National Academy of Science's Committee on Hearing, Bioacoustics and Biomechanics. This dosage-response relationship between C-weighted DayNight Average Sound Level and the prevalence of annoyance with high energy impulsive sounds was derived from limited amounts of information about community response to regular, prolonged, and expected exposure to artillery and sonic booms. U.S. Army Regulation 201 adapts this approach to predictions of the acceptability of impulsive noise exposure in communities. This regulation infers equivalent degrees of effect with respect to a well known dosage-response relationship for general (nonimpulsive) transportation noise. Differences in prevalence of annoyance predicted by various relationships lead to different predictions of the compatibility of land uses with sonic boom exposure. An examination of these differences makes apparent several unresolved issues in current practice for predicting and interpreting the prevalence of annoyance due to sonic boom exposure.

Fidell, Sanford↗
NASA NTRS1992

Sonic boom acceptability studies

The determination of the magnitude of sonic boom exposure which would be acceptable to the general population requires, as a starting point, a method to assess and compare individual sonic booms. There is no consensus within the scientific and regulatory communities regarding an appropriate sonic boom assessment metric. Loudness, being a fundamental and well-understood attribute of human hearing was chosen as a means of comparing sonic booms of differing shapes and amplitudes. The figure illustrates the basic steps which yield a calculated value of loudness. Based upon the aircraft configuration and its operating conditions, the sonic boom pressure signature which reaches the ground is calculated. This pressure-time history is transformed to the frequency domain and converted into a one-third octave band spectrum. The essence of the loudness method is to account for the frequency response and integration characteristics of the auditory system. The result of the calculation procedure is a numerical description (perceived level, dB) which represents the loudness of the sonic boom waveform.

Shepherd, Kevin P.↗
NASA NTRS1994

A laboratory study of subjective annoyance response to sonic booms and aircraft flyovers

Three experiments were conducted to determine subjective equivalence of aircraft subsonic flyover noise and sonic booms. Two of the experiments were conducted in a loudspeaker-driven sonic boom simulator, and the third in a large room containing conventional loudspeakers. The sound generation system of the boom simulator had a frequency response extending to very low frequencies (about 1 Hz) whereas the large room loudspeakers were limited to about 20 Hz. Subjective equivalence between booms and flyovers was quantified in terms of the difference between the noise level of a boom and that of a flyover when the two were judged equally annoying. Noise levels were quantified in terms of the following noise descriptors: Perceived Level (PL), Perceived Noise Level (PNL), C-weighted sound exposure level (SELC), and A-weighted sound exposure level (SELA). Results from the present study were compared, where possible, to similar results obtained in other studies. Results showed that noise level differences depended upon the descriptor used, specific boom and aircraft noise events being compared and, except for the PNL descriptor, varied between the simulator and large room. Comparison of noise level differences obtained in the present study with those of other studies indicated good agreement across studies only for the PNL and SELA descriptors. Comparison of the present results with assessments of community response to high-energy impulsive sounds made by Working Group 84 of the National Research Council's Committee on Hearing, Bioacoustics, and Biomechanics (CHABA) showed good agreement when boom/flyover noise level differences were based on SELA. However, noise level differences obtained by CHABA using SELA for aircraft flyovers and SELC for booms were not in agreement with results obtained in the present study.

Leatherwood, Jack D.↗
NASA NTRS1994

Second Microgravity Fluid Physics Conference

The conference's purpose was to inform the fluid physics community of research opportunities in reduced-gravity fluid physics, present the status of the existing and planned reduced gravity fluid physics research programs, and inform participants of the upcoming NASA Research Announcement in this area. The plenary sessions provided an overview of the Microgravity Fluid Physics Program information on NASA's ground-based and space-based flight research facilities. An international forum offered participants an opportunity to hear from French, German, and Russian speakers about the microgravity research programs in their respective countries. Two keynote speakers provided broad technical overviews on multiphase flow and complex fluids research. Presenters briefed their peers on the scientific results of their ground-based and flight research. Fifty-eight of the sixty-two technical papers are included here.

Source record↗
NASA NTRS1994

Residents' reactions to long-term sonic boom exposure: Preliminary results

This presentation is about residents' reactions to sonic booms in a long-term sonic boom exposure environment. Although two phases of the data collection have been completed, the analysis of the data has only begun. The results are thus preliminary. The list of four authors reflects the complex multi-disciplinary character of any field study such as this one. Carey Moulton is responsible for Wyle Laboratories' acoustical data collection effort. Robert Baumgartner and Jeff Thomas of HBRS, a social science research firm, are responsible for social survey field work and data processing. The study is supported by the NASA Langley Research Center. The study has several objectives. The preliminary data addresses two of the primary objectives. The first objective is to describe the reactions to sonic booms of people who are living where sonic booms are a routine, recurring feature of the acoustical environment. The second objective is to compare these residents' reactions to the reactions of residents who hear conventional aircraft noise around airports. Here is an overview of the presentation. This study will first be placed in the context of previous community survey research on sonic booms. Next the noise measurement program will be briefly described and part of a social survey interview will be presented. Finally data will be presented on the residents' reactions and these reactions will be compared with reactions to conventional aircraft. Twelve community studies of residents' reactions to sonic booms were conducted in the United States and Europe in the 1960's and early 1970's. None of the 12 studies combined three essential ingredients that are found in the present study. Residents' long-term responses are related to a measured noise environment. Sonic booms are a permanent feature of the residential environment. The respondents' do not live on a military base. The present study is important because it provides the first dose/response relationship for sonic booms that could be expected to apply to residents in civilian residential areas.

Fields, James M.↗
NASA NTRS1994

NAFTA literature at the International Trade Commission library

Most of the US official materials regarding NAFTA originate in the Executive Office of the President, especially the Office of the United States Trade Representative. These materials can be purchased from the U.S.G.P.O. There were also numerous Congressional hearings; many of which are probably now out of print, government agencies and the public are welcome to make copies of the ones in the collections of the ITC libraries. One of the most important sources of materials available in electronic format is the National Trade Data Base, produced by the Department of Commerce. This is a collection of at least 120 separate files containing documents relating to trade. It includes several files specifically on NAFTA, including the text of the treaty. It is available as two CD-ROM's, issued monthly, or on Internet.

Root, Elizabeth A.↗
NASA NTRS1995

Leak detection utilizing analog binaural (VLSI) techniques

A detection method and system utilizing silicon models of the traveling wave structure of the human cochlea to spatially and temporally locate a specific sound source in the presence of high noise pandemonium. The detection system combines two-dimensional stereausis representations, which are output by at least three VLSI binaural hearing chips, to generate a three-dimensional stereausis representation including both binaural and spectral information which is then used to locate the sound source.

Hartley, Frank T.↗
NASA NTRS1993

A microbased shared virtual world prototype

Virtual reality (VR) allows sensory immersion and interaction with a computer-generated environment. The user adopts a physical interface with the computer, through Input/Output devices such as a head-mounted display, data glove, mouse, keyboard, or monitor, to experience an alternate universe. What this means is that the computer generates an environment which, in its ultimate extension, becomes indistinguishable from the real world. 'Imagine a wraparound television with three-dimensional programs, including three-dimensional sound, and solid objects that you can pick up and manipulate, even feel with your fingers and hands.... 'Imagine that you are the creator as well as the consumer of your artificial experience, with the power to use a gesture or word to remold the world you see and hear and feel. That part is not fiction... three-dimensional computer graphics, input/output devices, computer models that constitute a VR system make it possible, today, to immerse yourself in an artificial world and to reach in and reshape it.' Our research's goal was to propose a feasibility experiment in the construction of a networked virtual reality system, making use of current personal computer (PC) technology. The prototype was built using Borland C compiler, running on an IBM 486 33 MHz and a 386 33 MHz. Each game currently is represented as an IPX client on a non-dedicated Novell server. We initially posed the two questions: (1) Is there a need for networked virtual reality? (2) In what ways can the technology be made available to the most people possible?

Pitts, Gerald↗
NASA NTRS1995

Emergency vehicle alert system (EVAS)

The Emergency Vehicle Alert System (EVAS) program is sponsored by the NASA/MSFC Technology Utilization (TU) office. The program was conceived to support the needs of hearing impaired drivers. The objective of the program is to develop a low-cost, small device which can be located in a personal vehicle and warn the driver, via a visual means, of the approach of an emergency vehicle. Many different technologies might be developed for this purpose and each has its own advantages and drawbacks. The requirements for an acoustic detection system, appear to be pretty stringent and may not allow the development of a reliable, low-cost device in the near future. The problems include variations in the sirens between various types of emergency vehicles, distortions due to wind and surrounding objects, competing background noise, sophisticated signal processing requirements, and omni-directional coverage requirements. Another approach is to use a Radio Frequency (RF) signal between the Emergency Vehicle (EV) and the Personal Vehicle (PV). This approach requires a transmitter on each EV and a receiver in each PV, however it is virtually assured that a system can be developed which works. With this approach, the real technology issue is how to make a system work as inexpensively as possible. This report gives a brief summary of the EVAS program from its inception and concentrates on describing the activities that occurred during Phase 4. References 1-3 describe activities under Phases 1-3. In the fourth phase of the program, the major effort to be expended was in development of the microcontroller system for the PV, refinement of some system elements and packaging for demonstration purposes. An EVAS system was developed and demonstrated which used standard spread spectrum modems with minor modifications.

Reed, Bill↗
NASA NTRS1996

NASA Rat Acoustic Tolerance Test 1994-1995: 8 kHz, 16 kHz, 32 kHz Experiments

Adult male Sprague-Dawley rats were exposed to chronic applied sound (74 to 79 dB, SPL) with octave band center frequencies of either 8, 16 or 32 kHz for up to 60 days. Control cages had ambient sound levels of about 62 dB (SPL). Groups of rats (test vs. control; N=9 per group) were euthanized after 0. 5. 14, 30, and 60 days. On each euthanasia day, objective evaluation of their physiology and behavior was performed using a Stress Assessment Battery (SAB) of measures. In addition, rat hearing was assessed using the brain stem auditory evoked potential (BAER) method after 60 days of exposure. No statistically significant differences in mean daily food use could be attributed to the presence of the applied test sound. Test rats used 5% more water than control rats. In the 8 kHz and 32 kHz tests this amount was statistically significant(P less than .05). This is a minor difference of questionable physiological significance. However, it may be an indication of a small reaction to the constant applied sound. Across all test frequencies, day 5 test rats had 6% larger spleens than control rats. No other body or organ weight differences were found to be statistically significant with respect to the application of sound. This spleen effect may be a transient adaptive process related to adaptation to the constant applied noise. No significant test effect on differential white blood cell counts could be demonstrated. One group demonstrated a low eosinophil count (16 kHz experiment, day 14 test group). However this was highly suspect. Across all test frequencies studied, day 5 test rats had 17% fewer total leukocytes than day 5 control rats. Sound exposed test rats exhibited 44% lower plasma corticosterone concentrations than did control rats. Note that the plasma corticosterone concentration was lower in the sound exposed test animals than the control animals in every instance (frequency exposure and number of days exposed).

Mele, Gary D.↗
NASA NTRS1996

Third Microgravity Fluid Physics Conference

The conference's purpose was to inform the fluid physics community of research opportunities in reduced-gravity fluid physics, present the status of the existing and planned reduced gravity fluid physics research programs, and inform participants of the upcoming NASA Research Announcement in this area. The plenary sessions provided an overview of the Microgravity Fluid Physics Program, present and future areas of emphasis, information on NASA's ground-based and space-based flight research facilities-especially use of the International Space Station, and the process by which future investigators enter the program. An international forum offered participants an opportunity to hear from Russian speakers about their microgravity research programs. Three keynote speakers provided broad technical overviews on the history and future development of the moon and on multiphase flow and complex fluids research. One keynote paper and an extended abstract are included in the proceedings. One hundred and thirty-two technical papers were presented in 28 sessions. Presenters briefed their peers on the scientific results of their ground-based and flight research. One hundred and twenty-two papers are included here.

Source record↗
NASA NTRS1996

NASA Rat Acoustic Tolerance Test 1994-1995

The major objective of this Cooperative Agreement was to develop a noise level specification for laboratory rats in the Centrifuge Facility Specimen Chambers (Space Station Biological Research Project), and to validate the specification for 3 noise octave bands: center frequencies 8 kHz, 16, kHz, and 32 kHz. This has been accomplished. Objective measures were used to verify that the chronic noise exposure was not harmful to the animals from physiological and behavioral perspectives. These measures were defined in the Stress Assessment Battery Validation for the Rat Acoustic Tolerance Test. In addition, the effects of the chronic noise exposure on rat hearing was assessed by the Brainstem Auditory Evoked Potential Method (BAER).

Holley, Daniel C.↗
NASA NTRS1994

A Basis for Solid Modeling of Gear Teeth with Application in Design and Manufacture

This paper discusses a new approach to modeling gear tooth surfaces. A computer graphics solid modeling procedure is used to simulate the tooth fabrication processes. This procedure is based on the principles of differential geometry that pertain to envelopes of curves and surfaces. The procedure is illustrated with the modeling of spur, helical, bevel, spiral bevel and hypoid gear teeth. Applications in design and manufacturing arc discussed. Extensions to nonstandard tooth forms, to cams, and to rolling element hearings are proposed.

Huston, Ronald L.↗
NASA NTRS1995

The Octavolateralis System and Mauthner Cell: Interactions and Questions

This paper is an overview of some of the major points to arise in the accompanying contributions of this special symposium issue. The symposium papers arose out of discussions among investigators interested in the inner ear and Mauthner cell, with the focus on hydrodynamic components that activate the Mauthner cell through the octavolateralis system. The intention of the symposium was to investigate the possibility of using our knowledge of the Mauthner system to help understand acoustic processing by the ear, and of using, our knowledge of fish hearing to better understand Mauthner cell function. This is the first attempt to take a broad look at both systems to see how they might function together. As such, these proceedings can serve as a mini-tutorial for investiaators interested in one system or the other. In this summary paper we also identify some of the major uncertainties in our understanding of the ear-Mauthner connection. These include questions about: (1) the identity of the acoustic stimuli that are neuroethologically relevant to the Mauthner system; (2) the relative importance of the various octavolateralis inputs (acoustic, vestibular, or lateral line); (3) the contribution of the different various acoustic endorgans to the Mauthner system; (4) whether the Mauthner system can distinguish sound source location; and (5) whether Mauthner neurobiology is compatible with the prevailing model (the phase model) for determining sound source location by fishes. We believe these issues provide potentially useful avenues of future investigation that should give important insights into both acoustic processing by fish and the function of the Mauthner system.

Eaton, Robert C.↗
NASA NTRS1997

An Engineering Approach to Management of Occupational and Community Noise Exposure at NASA Lewis Research Center

Workplace and environmental noise issues at NASA Lewis Research Center are effectively managed via a three-part program that addresses hearing conservation, community noise control, and noise control engineering. The Lewis Research Center Noise Exposure Management Program seeks to limit employee noise exposure and maintain community acceptance for critical research while actively pursuing engineered controls for noise generated by more than 100 separate research facilities and the associated services required for their operation.

Cooper, Beth A.↗
NASA NTRS1998

Advanced Low Emissions Subsonic Combustor Study

Recent advances in commercial and military aircraft gas turbines have yielded significant improvements in fuel efficiency and thrust-to-weight ratio, due in large part to increased combustor operating pressures and temperatures. However, the higher operating conditions have increased the emission of oxides of nitrogen (NOx), which is a pollutant with adverse impact on the atmosphere and environment. Since commercial and military aircraft are the only important direct source of NOx emissions at high altitudes, there is a growing consensus that considerably more stringent limits on NOx emissions will be required in the future for all aircraft. In fact, the regulatory communities have recently agreed to reduce NOx limits by 20 percent from current requirements effective in 1996. Further reductions at low altitude, together with introduction of limits on NOx at altitude, are virtual certainties. In addition, the U.S. Government recently conducted hearings on the introduction of federal fees on the local emission of pollutants from all sources, including aircraft. While no action was taken regarding aircraft in this instance, the threat of future action clearly remains. In these times of intense and growing international competition, the U.S. le-ad in aerospace can only be maintained through a clear technological dominance that leads to a product line of maximum value to the global airline customer. Development of a very low NOx combustor will be essential to meet the future needs of both the commercial and military transport markets, if additional economic burdens and/or operational restrictions are to be avoided. In this report, Pratt & Whitney (P&W) presents the study results with the following specific objectives: Development of low-emissions combustor technologies for advances engines that will enter into service circa 2005, while producing a goal of 70 percent lower NOx emissions, compared to 1996 regulatory levels. Identification of solution approaches to barriers to the productization and economic viability of the low-emissions technologies. Preparation of these technologies to facilitate an annular rig high-pressure demonstration.

Smith, Reid↗