Noise Off Research Articles

Use of Plat-Bar Electrode Media to Detect Partial Discharge in Epoxy Resin Materials on PCB Surfaces

The electric power system must have a protection system with reliable electric power isolation, so that the supply of electrical energy works properly and optimally. There are several kinds of disturbances in the electric power distribution system, one of which is a partial discharge. This study aims to investigate the effect of plate-rod electrodes on partial discharge, partial discharge voltage limits in solid insulation, and the characteristics of partial discharge in electrode media, and waveforms in partial discharge detection sensors. After conducting research, it was found that in the plate-rod type electrode media, the PDIV voltage appeared earlier than the plate-plate electrode media due to the cross-sectional area of the electrode media. And the limit of the pre-discharge voltage of PCB type solid insulation on the plate-bar electrodes is at a voltage of 1.3 kV. Several indicators to determine the characteristics of the partial discharge are background noise off (BGN off), background noise on (BGN on), partial discharge inception voltage (PDIV), and partial discharge voltage. After being examined, the value of each partial discharge detection voltage was obtained at negative and positive polarity voltages on the electrode plates and plate needles respectively 2.85 kV, 2.95 kV and 1.32 kV, 1.57 kV.

The soundscape of the southern Gulf of Mexico (Veracruz and Campeche)

The southern part of the Gulf of Mexico is a large area where little is known about its soundscape. We measured the environmental noise in Laguna de Términos, Campeche, México from 2004 to 2008 in stations distributed homogeneously in this lagoon during 17 sampling periods using a digital audio tape recorder sampling at 48 kHz with 16 bits for 1 min at each station. We also measured the environmental noise off Alvarado, Veracruz, México in June 2023 using a digital audio tape recorder sampling at 96 kHz with 24 bits for 50 min at four stations. The environmental noise in the recordings was measured with a semi-automatic MATLAB routine designed for this purpose. We will present preliminary results on the environmental noise in these two coastal locations using snapping shrimp sounds as a measure to depict differences in time and space within and between locations. Changes in submarine environmental noise are helping us in understanding the effects of natural phenomena and antropogenic sounds in the distribution and abundance of marine wildlife, such as snapping shrimps and bottlenose dolphins. [Work supported by CONACyT-Campeche, PAPIIT&PASPA-UNAM, SMM, and UV.]

Ocean ambient noise off Chennai due to very severe cyclonic storm Vardah

Ocean ambient noise during the passage of a very severe cyclonic storm, Vardah, in the Bay of Bengal has been studied and presented in this paper. A cyclone named Vardah formed near the Andaman and Nicobar Islands on December 6, 2016. The intensified cyclonic storm crossed the south-eastern coast of India in the afternoon hours (local time) of December 12, 2016. During the passage of this cyclone, ocean underwater ambient noise time series data were acquired from the shallow waters of the south-eastern coast of India. In this paper, the noises pertaining to heavy rain and light rain (drizzling) during the cyclonic event have been analysed along with the high wind noise, and the individual power spectra for both the noises have been estimated.

Circadian Rhythm of Ambient Noise Off the Southeast Coast of India

An ambient noise system consisting of a vertical linear hydrophone array was deployed in the shallow waters off Chennai, southeast coast of India from 1 August to 16 September 2013 to record ambient ocean noise of frequencies up to 10[Formula: see text]kHz. Biological sounds, which are broadband, short duration signals resulting from Terapon theraps, a native species, are a prominent feature of the ocean soundscape. Terapon activity peaks at 8[Formula: see text]pm and 11[Formula: see text]pm, and its presence is not observed after 12 midnight in both the months. In the other period, the ambient noise fluctuation is due to wind and vessel traffic. Hence, the present study focuses on the description of the ambient noise fluctuation over two 12[Formula: see text]h periods, i.e., 12 midnight–12 noon considered as period I, and 12 noon–12 midnight as period II in order to show the circadian rhythm of ambient noise. In this study area, Terapon vocalization reached 25[Formula: see text]dB above the ambient noise level and it dominates the short-term spectra records in the 0.4–4[Formula: see text]kHz range. All Terapon signals had daily patterns of sound production with highest levels of activity after dusk during the study period. The result shows that the circadian rhythm of ambient noise is mainly of biological sound generated by Terapon and it is reported first time in the shallow waters off the southeast coast of India.

Flame Stability Measurement on Rectangular Slot Meso-Scale Combustor

The biggest problem of combustion in the micro-scale or meso-scale combustor is heat loss. Heat loss led to a difficult of stable flame. This research aims to elucidate the flame stabilization and flammability limit of LPG-oxygen premixed flame, temperature distribution and flame visualization. Flame stabilization and flammability limit map are shows in φ - U plane. The result shows that there are six regions in the map that is stable without noise, stable with noise, transition zone, dead zone, pseudo stable, and blow off. Measurement parameters are LPG-oxygen flow velocity at various equivalent ratio and temperature. The flame stabilization and flammability limit map within measurement parameters are discussed.

DETECTION OF WARBLE TONES IN WIDEBAND NOISE WITH AND WITHOUT HEARING PROTECTION DEVICES

Noise attenuation by linear hearing protection devices (HPDs) is considered to be independent of the environmental noise level. Linearity of HPDs is one of the basic assumptions underlying the Real Ear Attenuation at the Threshold (REAT) method of HPD testing, which utilizes quiet conditions. However, non-linear growth of masking at high intensity levels may result in the effects of HPDs on detection of speech and warning signals being different from those at high noise levels. The purpose of this study was to determine if the non-linear growth of masking can affect detection of warble signals by persons using HPDs in wideband noise presented at the 100 dB(A) level. Audiometric thresholds of hearing of 10 listeners were measured under four experimental conditions: (1) noise off, HPDs off (condition C1); (2) noise off, HPDs on (condition C2); (3) noise on, HPDs on (condition C3); and (4) noise on, HPDs off (condition C4). The results of this study indicate that detection of signals by persons using HPDs in noise < 100 dB(A) can be well predicted from noise attenuation characteristics of HPDs measured in quiet without the need for a correction factor accommodating non-linear growth of masking. This finding has implications for predicting the audibility of warning signals in noise by persons wearing HPDs.

Effects of anxiolytic and antidepressant drugs on long-lasting behavioural deficits resulting from one short stress experience in male rats.

Exposure of male Wistar rats to one single session of ten inescapable footshocks induces changes in the behavioural responses to environmental stimuli as measured in the "noise test" 14 days later. Shocked (S) rats showed decreased locomotion and rearing during the first 3 min of exposure to a novel environment compared to control (C) rats. When the 85 dB background noise was switched off a marked immobility response emerged in S rats, concomitant with a further decrease in locomotion and rearing. In response to noise off, C rats showed hardly any immobility and a much smaller reduction in locomotion and rearing compared to S rats. These long-lasting changes in behaviour were not reversed by acute treatment with the antidepressants fluvoxamine (3.0-30.0 mg/kg) and desmethylimipramine (DMI, 2.5-10.0 mg/kg) injected IP 30 min before the noise test on day 14 following the shock session. Chronic treatment (day 1 to day 14) with fluvoxamine or DMI did not reverse the behavioural deficits induced by shock exposure. Diazepam (0.6-5.0 mg/kg) administered acutely only reversed the effects of shock on locomotion during the first 3 min of the noise test. Chronic treatment with diazepam normalized the shock-induced decrease in locomotion and attenuated the rearing decrease during the first 3 min of the test, and partially restored shock-induced changes in behavioural response to switching off the noise. The most potent drug in this study was the 5-HT1A receptor agonist flesinoxan (0.3-3.0 mg/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Measurements of man-made underwater noise off North Slope, Alaska

Recordings of man-made underwater noise in the Barrow and Prudhoe areas provided acoustic measurements of helicopters, cranes, detonations, power plants, island building, seismic profiling, off-shore drilling, human movements, unidentified machinery, tugs, and other marine service craft. The recordings, made in winter, spring, and fall, were obtained from under the ice, or from leads, polynyas, or open water at distances from a few meters to about 185 km from the source. Estimated overall source levels varied from 40 to over 200 dB re 1 μPa at 1 m, in the effective bandwidths. Principal acoustic energy occurred in bands falling between 10 Hz and 13 kHz. Among the lowest levels encountered were those from the sounds of oil exploration drilling. The highest were from seismic profiling. Durations of man-made sounds varied from msec (metallic impulses) to continuous (line spectra from engines). In terms of frequency (Hz), duration, and power, many of the measured man-made sounds had the potential for masking underwater animal vocalizations or other acoustic signals. Speculations are made on the possibility of inducing avoidance or even deafness. [Work supported by AEWC, NOAA/OCSEAP.]

An experimental analysis of impulsivity and impulse control in humans

In choosing between small, immediate and large, delayed reward, an organism behaves impulsively if it chooses the small reward and shows impulse control if it chooses the large reward. Work with nonhumans suggests that impulsivity and impulse control may be derived from gradients of delayed reinforcement. A model developed by Ainslie and by Rachlin suggests that preference for the rewards should be a function of when the choice is made: small reward with no delay may be preferred to large reward with delay X, but adding delay T to both alternatives should shift preference to the large reward. Three experiments investigated this preference reversal in humans, using termination of 90 dba white noise as the reinforcing event. Experiment 1 showed that under some instructional conditions 90-sec noise off with no delay was preferred over 120-sec noise off after a 60-sec delay, but that preference shifted to the large reward when a 15-sec delay ( T) was added to both alternatives. Experiment 2 replicated this preference reversal under two conditions of large, delayed reward, and with three rather than two values of T. Experiment 3 confirmed this effect of T and showed that some humans committed themselves to the large reward when commitment could be made some time before presentation of the reward alternatives. These data support the Ainslie-Rachlin model and extend it to human choice behavior.

Wind dependence of low‐frequency noise off Cape North, Nova Scotia

Over the period September 1968–June 1969 ambient noise spectrum measurements were made using a bottom‐mounted installation in the Cabot Strait just off the northern tip of Nova Scotia. Several noise‐producing mechanisms were identified, including wind‐generated noise, ship‐produced noise, and noise due to flow past the hydrophone. It was possible to identify and eliminate those data which were contaminated by high flow noise and to a lesser extent to eliminate samples contaminated by nearby shipping. Analysis in two ⅓‐octave bands below 10 Hz shows that the spectrum levels between 10 and 4 Hz are wind dependent.

Effects of density of noise field and delay on information-processing of patterned inputs.

The present paper extends current research on pattern recognition to investigate the effects of density of noise field and delay (off) times. The results indicate major effects due to density of the noise field, on time and off time. Recognition initially declined as the density of the interference increased, then subsequently leveled off at higher interference levels. The effect of density of noise field on recognition was not consistent across all levels of either on time or off time. There was a wide range of processing-ability among Ss. Some subjects were capable of high levels of performance for very fast input rates. There was a high degree of consistency among Ss in the relative difficulty of the letters.

Development of vibration pick‐up type auditory canal microphone and its daily application

As voice transmitting microphones, especially in noisy environments, as well as in situations in which the free use of both hands is restricted, monodirectional, noise canceling, and laryngeal microphones have been widely used. These conventional transducers, however, have not been satisfactory with regard to the elimination of the ambient noise, positioning of the microphone, the feeling of use, and the clarity of the voice. We developed a vibration pickup‐type auditory canal microphone by use of a piezoelement which is not influenced by sound pressure itself. The advantage of use of this microphone is that there is no problem in security and safety thanks to rich information from outside because this microphone works well without tight insertion into the ear canal. In addition, this microphone can be used as a howlingless microphone because it does not sense sound pressure. The nature of non‐interference had made it possible to intergrate it with a sound‐pressure‐type earphone, permitting simultaneous communications without closing the auditory canal. Moreover, it does not need an ear muff for transmission even in highly noise levels of more than 100 dB thanks to its excellent ability of shutting noise off.

Designs for Improvements in the Quality of Life in Downtown Cores

We need to have many times over the quantity and quality of information already stored in mankind's memory bank. Moreover, because the problems are new, the type of knowledge we require is also new. What follows is a non-rank-ordered inventory of questions urgently needing answers if we are to solve the problems of urban environments, which contain three-quarters of the Western world's population. If we are to survive in gigantic cities, what is the maximal size of these cities beyond which they become rat traps ? Within them, what are the optimal living, working, and walking densities below which they become deadly thoroughfares and above which they become cesspools of social pathology ? What are the optimal divisions and arrangements of spaces, both public and private, beyond which perceived congestion and lack of ownership responsibility and pride potentiate the hostility that comes from powerlessness and leads to violence and crime, or at least to anonymity, indifference, and anomie ? What is the minimal square footage of living space below which man cannot function as a truly human being ? What is the maximal height above which there is nothing but alienation, vandalized elevators and corridors ? What is the noise level above which sleepdreams are banished and insanity invades by night, and the cost in energy consumed in mentally turning noise off leaves us listless by day ? (In this context, how much interruption and pressure from sound, for instance, can a child tolerate in an open-plan school

Theory of LDV Tracking Systems

The application of frequency-tracking systems to the analysis of laser doppler velocimeter (LDV) signals degraded by background noise has been studied both theoretically and experimentally. Expressions are derived for both the correlation function and the expected value of the phase derivative in the general case of noise off center from the Doppler frequency, and these results are specialized to specific cases of practical interest. Laboratory measurements of output signal-to-noise ratio (SNR) and dc error, for varying input SNR and noise center frequency offset, show good agreement with the theoretical predictions.

Interaction of continuous and impulse noise: audiometric and histological effects.

Continuous and impulse noises were combined to model more realistic noise environments. Monaural chinchillas were exposed to one of the following conditions: (a) 50 impulses with 40-μsec. A duration at 158-dB-SPL peak pressure, 1/min; (b) 95-dB-SPL continuous noise at 2–4 kHz for one hour; (c) superimposed combination of the continuous and impulse noise; (d) 50 impulses with a 40-μsec. A duration at 175-dB-SPL peak pressure, 1/min; (e) interrupted combination of the continuous and impulse noise with the continuous noise off for 2 sec during the impulse delivery. Quiet thresholds were measured before and after exposure using the auditory evoked response and histology was obtained using the surface preparation technique. The audiometric and histological findings agree in showing that the superimposed combination of two noise exposures, shown to be safe for the chinchilla, produces traumatic effects that more than exceed the additive effects of either component. The existing damage risk criteria do not provide guidelines for such noise combinations.

The Interaction of Continuous and Impulse Noise: Audiometric Effects

Continuous and impulse noises, considered “safe” by existing damage risk criteria (DRC), were combined to model more realistic noise environments. Monaural chinchillas (23) were exposed to one of the following conditions: (a) 95 dB SPL continuous noise at 2–4 kHz for 1 h; (b) 50 impulses with a 40-μsec A duration at 158 dB SPL peak pressure; (c) interrupted combination of the continuous and impulse noise with the continuous noise off for 2 sec during the impulse delivery; (d) superimposed combination of the continuous and impulse noise. Quiet thresholds were measured before and after exposure at 0.25, 0.5, 1, 2, 4, and 8 kHz using the averaged evoked response technique. Recovery was monitored for 31 days. The median recovery from the 95 dB SPL continuous and 158 dB impulse was complete by 30 h. The interrupted combination produced temporary threshold shifts (TTS) of 50–60 dB at 2, 4, and 8 kHz that required four days to recover. The superimposed combination produced, 30 dB TTS at 0.25, 0.5, and 1 kHz, 70–90 dB TTS at 2, 4, and 8 kHz, and a final median audiogram typical of noise induced sensorineural hearing loss with 30–40 dB PTS at 2, 4, and 8 kHz.

Absolute auditory threshold and threshold of unpleasantness of chronic schizophrenic patients and normal controls.

The method of average error was modified tor research in schizophrenia and was used in establishing both the absolute auditory threshold and the threshold of unpleasantness. The results showed chronic schizophrenic patients had a higher absolute threshold but a lower threshold for when a tone became unpleasantly loud. The results add evidence that chronic schizophrenic patients find external stimulation aversive; they point out the narrow range of auditory stimuli in which schizophrenics function; and suggest that the same auditory stimuli cannot be considered equivalent for schizophrenic patients and normal controls. The results of a stimulus-seeking experiment showed that chronic, nonparanoid schizophrenic patients preferred a noise stimulus of varying intensity to be off, while normal controls preferred it on (Levine, 1967). These results were interpreted as indicating a motivational process in which schizophrenic patients avoid external stimulation simply because external stimulation is unpleasant to them. However, another explanation for the findings is that schizophrenic patients have greater auditory sensitivity than normals. If patients were more sensitive, then the stimuli used would not be perceptually equivalent and would tend to be differentially aversive. The patients would then be expected to show the obtained results of preferring the noise off. Previous research in schizophrenic audition

Escape from noise.

Rats were trained to press a key for 1-min. periods of escape from noise. The louder the noise the longer Ss kept it off. The performance was lower than that which has been obtained when Ss can keep noise off by remaining in a safe position. A within-session performance decrement was observed.

Characteristics of Ambient Noise off Bermuda

The data resulting from a 23-month ambient-noise measurement program are reviewed. 2-min-long broad-band magnetic tape recordings were made every 2 h, from omnidirectional hydrophones at fixed locations. Ten noise-level readings were made in each of ten logit frequency bands between 100 and 1000 cps from each recording. The mean value obtained from each set of ten readings was taken as the representative level of that 2-min sample in subsequent data processing. The data clearly show the dependence of ambient-noise level upon wind-speed and a lesser dependence upon wave height. The spectrum is seen to change markedly with wind speed and to suggest the presence of both wind-dependent and non wind-dependent mechanisms. Level-distribution histograms show dependence upon both frequency and season. The standard deviation is shown to be a function of both frequency and wind speed. Power-spectrum analyses indicate the occurrence of cyclical noise variations with periods up to 55 h.