Showing papers on "Impulse noise published in 1986"

Nonlinear mean filters in image processing

Abstract: The use of nonlinear means in image processing is introduced. The properties of these means in the presence of different types of noise are investigated. It is shown that nonlinear filters based on these means behave well for both additive and impulse noise. Their performance in the presence of signal dependent noise is satisfactory. They preserve the edges better than linear filters, and they reject the noise better than median filters.

Impulse noise: critical review.

Abstract: A review of the last 10 years of research on impulse noise reveals certain insights and perspectives on the biological and audiological effects of exposures to impulse noise. First, impulse noise may damage the cochlea by direct mechanical processes. Second, after exposure to impulse noise, hearing may recover in an erratic, nonmonotonic pattern. Third, even though the existing damage‐risk criteria evaluate impulse noise in terms of level, duration, and number, often parameters such as temporal pattern, waveform, and rise time are also important in the production of a hearing loss. Fourth, the effects of impulse noise are often inconsistent with the principle of the equal energy hypothesis. Fifth, impulse noise can interact with background continuous noise to produce greater hearing loss than would have been predicted by the simple sum of the individual noises.

Basic and Applied Aspects of Noise-Induced Hearing Loss

Abstract: Anatomical Bases of Noise Induced Hearing Loss.- Morphology of Stereocilia on Cochlear Cells after Noise Exposure.- Mechanical Changes in the Stereocilia following Overstimulation: Observations and Possible Mechanisms.- The Morphology of Sterocilia and Their Coss-Links in Relation to Noise Damage in the Guinea Pig.- Synaptology of the Cochlea: Different Types of Synapse, Putative Neurotransmitters and Physiopathological Implications.- The Morphology of the Normal and Pathological Cell Membrane and Junctional Complexes of the Cochlea.- Mechanically Induced Morphological Changes in the Organ of Corti.- The Application of Morphometric and Stereological Principles to Epithelial Tissue: Theoretical and Practical Considerations.- Morphometric Methods for the Evaluation of the Cochlear Microvasculature.- Physiological Changes with Noise-Induced Hearing Loss.- Mechanical Correlates of Noise Trauma in the Mammalian Cochlea.- Auditory Sensitivity, Auditory Fatigue and Cochlear Mechanics.- The Response of Mammalian Cochlear Hair Cells to Acoustic Overstimulation.- Structure-Function Correlation in Noise-Damaged Ears: A Light and Electron-Microscopic Study.- Psychophysical and Physiological Aspects of Auditory Temporal Processing in Listeners with Noise-Induced Sensorineural Hearing Loss.- Increase in Central Auditory Responsiveness During Continuous Tone Stimulation or Following Hearing Loss.- Adjustments in Coronary Blood with Noise Stimulation.- Critical Periods of Susceptibility to Noise-Induced Hearing Loss.- The Acoustic Reflex in Industrial Impact Noise.- Noise History, Audiometric Profile and Acoustic Reflex Responsivity.- Stimulation of the Middle Ear Acoustic Reflex Applied to Damage-Risk for Hearing Loss Produced by Burst Fire.- Psychoacoustic Performance Changes with Noise-Induced Hearing Loss.- Changes in Auditory Threshold During and After Long Duration Noise Exposure: Species Differences.- The Curious Half-Octave Shift: Evidence for a Basalward Migration of the Traveling-Wave Envelope with Increasing Intensity.- Human Noise Experiments Using a Temporary Threshold Shift Model.- The Relationship Between Speech Perception and Psychoacoustical Measurements in Noise-Induced Hearing Loss Subjects.- Speech Perception in Individuals with Noise-Induced Hearing Loss and its Implication for Hearing Loss Criteria.- The Perception of Synthetic Speech in Noise.- Concept - Reference Coherence in Speech Perception: Consequences for Native and Second Language Speech Comprehension in Noise.- Impulse Noise/Blast Wave Effects.- A Parametric Evaluation of the Equal Energy Hypothesis.- Impulse Noise Hazard as a Fuction of Level and Spectral Distribution.- Experimental Studies of Impulse Noise.- The Role of Peak Pressure in Determining the Auditory Hazard of Impulse Noise.- Effects of Weapon Noise on Hearing.- Critical Peak Level for Impulse Noise Hazard: Permanent Hearing Threshold Shifts in Military Drill Squads Following Known Variation of Impulse Noise Exposure.- Can TTS be an Indicator for Individual Susceptibility to PTS?.- Field Studies on Impluse Noise Annoyance in the Environment of Garrison Firing Range.- The Results of Long-Term Field Studies on Acoustic Traumata in Military Personnel.- Effects of Blast Waves on Nonauditory Epithelial Tissue.- Nonauditory Effects of Repeated Exposures to Intense Impulse Noise.- Experimental and Analytical Studies of Blast Wave Effects on Major Organ Systems of the Body.- Complex and Interactin Effects of Noise.- Hearing in Fishermen and Coastguards.- Interactions Between Different Classes of Noise.- Some Issues Associated with Interactions Between Ototoxic Drugs and Exposure to Intense Sounds.- Hearing and Endocrine function.- A Pathway for the Interaction of Stress and Noise Influences on Hearing.- Implications for Noise Standards.- The Effects of Age, Otological Factors and Occupational Noise Exposure on Hearing Threshold Levels of Various Populations.- Current Perspectives on Issues in Personal Hearing Protection.- Hearing Conservation and Impulse Noise in the British Army.- Mathematical Simulation of the Cochlear Mechanism Applied to Damage-Risk Criteria for Impulse Noise.- Acoustic Reflex and Exchange Rate for White Noise Short Stimuli.- The Proposed ISO Standard Determination of Occupational Noise Exposure and Estimation of Noise-Induced Hearing Impairment.- President's Farewell Address.- French Abstracts.- Contributors.

Edge detection using median comparisons

Abstract: In this paper we describe a new edge detector based on differencing the median values of local image neighborhoods. Statistical and deterministic argument are given that suggest that this detector can be more effective than average-based detectors with similar configurations. Examples using images corrupted by Gaussian and impulse noise support the analytic results.

A Nonlinear Filter to Remove Impulse Noise from Meteorological Data

Abstract: Nonlinear median filters were modified to use threshold logic and used to remove impulse noise (spikes) from a set of meteorological data. The impulse noise in the dataset, which originated in the communications section of the Portable Automated Mesonet, could be characterized as random bit noise. Most of the pulses had a duration of one time interval, which in this case was one minute. The filters were effective irrespective of the frequency of occurrence and of the amplitude of the noise spikes. Pulses were removed even when the frequency of occurrence rose to every other data point as was observed in several short intervals. The amplitude of pulses removed ranged over three orders of magnitude.

The Loop Coverage Comparison Between TCM and Echo Canceller Under Various Noise Considerations

Abstract: This paper describes loop coverage evaluations of two-wire digital subscriber transmission systems to support the CCITT recommended 1-430 interface. Several range-limiting factors are discussed and a cable utility design for two representative two-wire digital subscriber transmission systems is presented. The two transmission systems are time compression multiplexing (TCM) and echo canceller (EC), utilizing the AMI line code and full cosine rolloff line equalization for both systems. A new impulse noise evaluation is applied to cable utility design, because impulse noise is one of the most stringent range-limiting factors, especially for TCM in utilizing existing subscriber loops. Comparison of TCM with EC is also carried out according to various range-limiting factors. As a result, it is noted that the 320 kbit/s line bit rate TCM is more applicable in NTT's exchange area coverage than the 160 kbit/s EC to achieve the 2B + D basic interface transmission.

Modeling and Analysis of Error Probability Performance for Digital Transmission Over the Two-Wire Loop Plant

Abstract: We describe a methodology for the characterization of the 2-wire twisted-pair subscriber loop plant for high-speed digital communications typical of evolving integrated service digital networks (ISDN's). Through use of this analytical/numerical approach it is possible to predict the resulting error probability performance as a function of signal-to-noise ratio for a given set of input parameters representing a particular subscriber loop and its noise environment, including such effects as intersymbol interference, crosstalk and impulse noise. The results are useful in penetration assessment studies of the loop plant population at a fixed grade of service measured objectively in terms of operating bit error probability. This approach is in contrast to simulation-based methodologies leading to subjective performance assessment criteria, such as eye opening measurements. In the present paper we describe the modeling assumptions together with the analytical/numerical techniques underlying this approach. Attention is restricted to time-compression multiplexing (TCM) schemes with bipolar line coding, although the approach is much more general. Numerical results are illustrated through sample graphical output of an extensive computer program implementing this approach. Finally, we illustrate the application of this approach to objective penetration assessment of the GTE subscriber loop plant utilizing data collected as part of an extensive recent survey.

The Role of Peak Pressure in Determining the Auditory Hazard of Impulse Noise

Abstract: 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 a DRC based on peak pressure can reflect accurately the hazard to hearing posed by impulse noise.

Mathematical Simulation of the Cochlear Mechanism Applied to Damage-Risk Criteria for Impulse Noise

Abstract: A mathematical simulation of the human hearing mechanism, involving the non-linear effect of the middle ear, has been used to compute the risk of impairment for hearing produced by impulse noise. This model provides, therefore, a reference method which can be used for evaluating the loudness of any kind of acoustical noise. The results of impulse noise analysis obtained from different damage-risk criteria can then be compared with the results of the theoretical model, allowing for evaluation of the respective merits of these criteria.

Digital high-speed sampling of combined exposure to noise and vibration.

Abstract: The digital high-speed sampling technique was applied to simultaneous measurements of exposure to noise and vibration among workers who used hand-held power tools in a shipyard. The transducers were two accelerometers and two microphones which measured the transmission of vibration acceleration from the handle of the tool to the wrist and the attenuation of noise by the earmuffs. The measurements were taken by a microcomputer-controlled digital multichannel sampling unit. An analogue-digital converter was used with a 100-kHz scanner for multichannel signal acquisition in the 10 kHz bandwidth. The sound pressure was A-weighted, and the vibration acceleration was both unweighted and weighted according to the guidelines of the International Organization for Standardization. Impulsiveness was determined as the difference between the peak and root-mean-square levels. The noise exposure was 81 dB during grinding and 85 dB during hammering. The earmuffs provided protection against impulse noise at least when the impulses contained high frequencies. The transmission loss of vibration acceleration between the tool handle and wrist was 45 dB for grinding and 29 dB for hammering. The transmission of noise and vibration was affected by the frequency content and impulsiveness of the signals.

High-energy impulsive noise assessment

Abstract: In 1977 and again in 1981, the National Research Council (NRC) concluded that the C‐weighted Day–Night Level was the best available measure with which to assess community response to high‐energy impulse noise. Rattles in homes were the major adverse factor indicated by sonic boom and blast noise studies and cited by the NRC reports. Studies, since 1981, by the U. S. Army further support the NRC conclusions. Despite this wide consensus, there remain advocates for using only the A‐weighting for measuring noise in the community—including that from high‐energy impulses. This letter covers issues not considered in the NRC reports and provides additional rationale for the use of C‐weighting, based on measurability and mitigation implications. This letter shows that impulsive noise is commonly hidden in other neighborhood sources when using A‐weighting, but only rarely hidden when using C‐weighting. There is a 10‐dB improvement in signal to noise when using C‐weighting. Also, A‐weighting can mislead the public since it implies large benefits (up to 15 dB) for mitigation techniques such as barriers or forests. Low‐frequency impulse energy, which rattles houses, is not attenuated by barriers or forests. Thus no large benefit is gained. C‐weighting predicts the correct answer—only a few decibels of attenuation.

Impulse Noise Hazard as a Function of Level and Spectral Distribution

Abstract: Given an interest in impulse noise, there are many research issues that could be addressed, but for practical application, two of them are especially important. Specifically, they are the roles played by level and spectral distribution of energy. So far as the auditory system is concerned, there must be some internally consistent answers. The practical problem is that the damage-risk criteria (DRC) in use in the world differ in their treatment of these two critical issues. Furthermore, the present research program is producing data that indicate that the current DRCs are fundamentally incorrect and that traditional theoretical approaches don’t work.

Simulation of TV Transmission Over the Communications Satellite Channel

Abstract: Time-domain simulation is used to evaluate NTSC and multiplexed analog component (MAC) television transmission over the Communications satellite channel using analog frequency modulation. The simulation program is used to measure transmission impairments caused by thermal noise, distortion resulting from spectral truncation by the band-limited channel, AM-to-PM conversion in the satellite TWTA, and the onset of impulse noise in the FM demodulator as the receiver approaches threshold. Although subjective testing is necessary before final comparisons can be made, the simulation results give insight into the sources of transmission impairments and the tradeoffs among certain transmission parameters.

A Parametric Evaluation of the Equal Energy Hypothesis

Abstract: A current issue of debate is whether the effects of impulse/impact noise are the same as the effects of continuous noise. Passchier-Vermeer [1] reviewed several demographic studies and reported that for equal amounts of sound energy, exposure to noises that had impulsive components produced larger amounts of hearing loss than the exposure to continuous noise. A series of laboratory studies, using an animal model of hearing loss, have shown that exposure to impulse noise of 140 dB or greater produces lesion in the cochlea that are probably mechanical in nature [2,3] and the pattern of recovery of auditory sensitivity following the exposure is often complicated; i. e., there is an initial period of recovery of sensitivity, then a reversal to higher levels of loss at 6 to 12 hours post-exposure, then a more gradual return to either a permanent hearing loss or to pre-exposure levels of auditory sensitivity [4,5].

A New Method of Assessing Receiver Performance in the Presence of Impulsive Noise

Abstract: A new method is proposed for assessing the performance of a radio receiver in the presence of impulsive noise. It involves selecting a criterion of performance, appropriate for the system under consideration (e.g., BER in data communication systems), and measuring isodegradation curves with respect to that criterion. A direct estimate of system performance can then be obtained using the noise amplitude distribution (NAD), one method being via the overlay technique. To demonstrate the validity of the method, three VHF/FM receivers have been tested in the laboratory. Results show that isodegradation curves in the new form give a better insight into performance degradation than those using the established criterion 20 dB quieting. It is suggested that receiver specifications should include a parameter related to performance in impulsive noise.

Noise rejection and processing circuit

Abstract: PURPOSE:To reject effectively impulse noise by sampling and A/D-converting a sound signal, D/A-converting the result, and restoring it into an original continuous wave by an interpolation filter. CONSTITUTION:The inputted sound signal (discriminator output) is subject to sampling, A/D conversion and D/A conversion normally, restored into an original continuous wave by an LPF and inputted to a sound amplifier. A signal superimposed on a pulse noise is subject to sampling, A/D conversion (while sampled pulse noise is rejected), correction by a filter DF and D/A conversion, restored into an original continuous wave (rejected pulse noise) by an LPFi, inputted to the sound amplifier, where the result is subject to noise rejection.

Experimental Studies of Impulse Noise

Abstract: Based on empirical data from continuous noise exposures, the equal energy hypothesis (EEH) seems to provide a useful approximation of a trading relation between the noise level and the exposure time when the risk for hearing damage is evaluated. The basis for the EEH is discussed by Henderson et al. [1] in this volume. From the EEH, damage risk criteria (DRC) have been derived that relate the risk of hearing loss to noise exposure.

Effects of Weapon Noise on Hearing

Abstract: “In military spheres, the need for prevention of weapon noise-induced hearing loss is receiving ever-increasing attention The question as to which impulse noises are hazardous and which are not is frequently raised, and research is being conducted in a number of countries to obtain data relating to these problems The approach has to be made along two lines: (1) to find a satisfactory method of measuring and expressing the physical characteristics of the noise, and (2) to assess the potential for auditory damage of various noise sources [1]” This statement, made by English and American scientists in 1968, is still up to date

Noise eliminating device

Abstract: PURPOSE:To eliminate surely an impulse noise and to attain miniaturization and light weight of a radio equipment by using a crystal filter giving a limit of a reception band and a flag group delay time. CONSTITUTION:When a pulse noise A is applied, a pulse noise shown in a waveform B is produced at an output of a broad band noise detector 16. On the other hand, a noise like a waveform D is produced at an output of a crystal filter BPF14 giving limit of reception band and flat group delay time. A delay pulse generator 17 produces leading with a delay of a prescribed time t1 from a leading (a) of the output waveform B and trailing by t2 from this point. Since the consecutive time t2 is a time including most of the pulse output of the BPF14, the impulse noise is eliminated surely.

Impulse noise removing processor

Abstract: PURPOSE:To supply the natural sound without a sense of incompatibility, to remove the impulse noise between discretes by sampling the sound signal and to obtain excellent noise removing processing effects by removing the pulse noise section by using a sampling frequency conversion. CONSTITUTION:A sound signal outputted by a distinguishing device 18 enters through a low-pass filter 34 of the invented circuit 30 to a sampled and hold circuit 36, and sampled at a frequency f1. Respective samples are converted to the digital value at an A/D converter 38, and by a noise detecting output from an impulse noise detecting device 32, the sample for the noise is removed. At a signal processor 40, respective samples which the A/D converter 38 outputs are sampled at a frequency fp again, low-pass filtering is executed for the resampled sample, and the result is resampled at a frequency f2 (here, fp=Mf1= Nf2, and M and N are integers and M, N is obtained). The output of the signal processor 40 is converted to an analog by a D/A converter 50, and through a low-pass filter 52, the analog sound signal, from which the noise is removed, is obtained.

A catv-based high-speed packet-switching network design

Abstract: A high-speed packet-switching data network to the home can be built on an existing, unmodified, residential cable television (CATV) system. This thesis considers the theoretical and practical technical aspects of providing such a service and suggests a possible system design. All network data must pass through the CATV hub, so the network design is divided into three major parts: Upstream transmission, downstream transmission, and access scheme. Upstream transmission is difficult because of the high noise level on the upstream channel caused by ingress of shortwave signals and impulse noise. The noise level is increased by the CATV system topology that funnels all system noise to the headend. Several noise-reduction techniques must be used simultaneously for robust upstream transmission. The downstream channel has low noise, but the data signal must be compatible with the CATV system, video signals and television receivers. Vistigial sideband data modulation is suggested for total system compatibility. Existing access schemes are suggested as possible solutions. The best techniques for upstream***-mission and access scheme are combined into a single proposed system.

The loop coverage comparison between TCM and echo canceller under various noise considerations

Abstract: This paper describes loop coverage evaluations of two-wire digital subscriber transmission systems to support the CCITT recommended 1-430 interface. Several range-limiting factors are discussed and a cable utility design for two representative two-wire digital subscriber transmission systems is presented. The two transmission systems are time compression multiplexing (TCM) and echo canceller (EC), utilizing the AMI line code and full cosine rolloff line equalization for both systems. A new impulse noise evaluation is applied to cable utility design, because impulse noise is one of the most stringent range-limiting factors, especially for TCM in utilizing existing subscriber loops. Comparison of TCM with EC is also carried out according to various range-limiting factors. As a result, it is noted that the 320 kbit/s line bit rate TCM is more applicable in NTT's exchange area coverage than the 160 kbit/s EC to achieve the 2B + D basic interface transmission.

Hearing Conservation and Impulse Noise in the British Army

Abstract: Army service has always presented a risk to hearing from impulse noise in addition to noise from small arms, with a typical peak pressure of 160 dB at the user’s ear; a number of weapon systems in current service give peak pressures up to 185 dB (35 kPa) in crew positions. To an increasing extent, soldiers are also exposed to continuous noise in vehicles or in workshops; these levels can exceed 100 dBA at the ear, even where hearing protection is used. The problem is becoming more acute, since the quest for more power from equipment of reduced size and weight tends to increase noise at the user’s position. At the same time, interest in hearing conservation measures is increasing, not only because of the greater risk of hearing loss, but also because awareness of the effects of noise is increasing as the use of monitoring audiometry becomes more widespread. It is therefore becoming vital to be able to predict the risk of hearing loss and the resulting disability from measurements (or, in the case of equipment still at the design stage, from predictions) of the noise exposure.

Acoustic Reflex and Exchange Rate for White Noise Short Stimuli

Abstract: The “equal energy principle” has been proposed as the basis of a damage risk criterion to set the limits for daily exposure to on-going noise for periods shorter or longer than 8 hours and to fluctuating, intermittent and impulse noise. The principle, supported by the studies of Elred et al. [1] and Kylin [2], was primarily validated by Burns and Robinson [3] for exposure to steady-state noise and then extended to other types of noise, including impulse exposure [4–8].