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PubMedDate not supplied

Aircraft noise, hearing ability, and annoyance.

The relationship between aircraft noise, loss of hearing, and annoyance was explored in a study in two schools located near an international airport in Taiwan. Sixth-grade students (N = 242) were recruited from two schools and were classified into high- and low-noise-exposure groups, based on environmental noise measurements. Personal-equivalent 24-h noise exposure was measured to determine noise exposure at the individual level, and it was compared with hearing threshold level and with aircraft noise measured at the environmental level. Individual hearing threshold levels did not differ between environmental high- and low-noise-exposure groups, as evidenced by the lack of difference between the two groups for noise exposure measured at the individual level. However, the proportion of students who were annoyed by aircraft noise was higher in the environmental high-noise-exposure group, although personal 24-h noise exposure was not a factor for annoyance. The results indicated that environmental noise measurement was not an appropriate criterion for assessment of auditory damage (or noise-induced hearing loss) in Taiwan. As well, aircraft-noise exposure in Taiwan did not appear to affect the hearing threshold but nonetheless annoyed schoolchildren near the airport.

Aircraft↗
PubMed2003

The effects of the amplitude distribution of equal energy exposures on noise-induced hearing loss: the kurtosis metric.

Seventeen groups of chinchillas with 11 to 16 animals/group (sigmaN = 207) were exposed for 5 days to either a Gaussian (G) noise or 1 of 16 different non-Gaussian (non-G) noises at 100 dB(A) SPL. All exposures had the same total energy and approximately the same flat spectrum but their statistical properties were varied to yield a series of exposure conditions that varied across a continuum from G through various non-G conditions to pure impact noise exposures. The non-G character of the noise was produced by inserting high level transients (impacts or noise bursts) into the otherwise G noise. The peak SPL of the transients, their bandwidth, and the intertransient intervals were varied, as was the rms level of the G noise. The statistical metric, kurtosis (beta), computed on the unfiltered noise beta(t), was varied 3 < or = beta(t) < or = 105. Brainstem auditory evoked responses were used to estimate hearing thresholds and surface preparation histology was used to determine sensory cell loss. Trauma, as measured by asymptotic and permanent threshold shifts (ATS, PTS) and by sensory cell loss, was greater for all of the non-G exposure conditions. Permanent effects of the exposures increased as beta(t) increased and reached an asymptote at beta(t) approximately 40. For beta(t) > 40 varying the interval or peak histograms did not alter the level of trauma, suggesting that, in the chinchilla model, for beta(t) > 40 an energy metric may be effective in evaluating the potential of non-G noise environments to produce hearing loss. Reducing the probability of a transient occurring could reduce the permanent effects of the non-G exposures. These results lend support to those standards documents that use an energy metric for gauging the hazard of exposure but only after applying a "correction factor" when high level transients are present. Computing beta on the filtered noise signal [beta(f)] provides a frequency specific metric for the non-G noises that is correlated with the additional frequency specific outer hair cell loss produced by the non-G noise. The data from the abundant and varied exposure conditions show that the kurtosis of the amplitude distribution of a noise environment is an important variable in determining the hazards to hearing posed by non-Gaussian noise environments.

Acoustic Stimulation↗
PubMed1998

Inner ear damage in guinea pigs exposed to stable and impulse noise.

OBJECTIVE: To investigate the inner ear damage after exposure to stable noise, impulse noise and stable plus impulse noise in guinea pigs. METHODS: Ninety-six healthy guinea pigs were divided into 3 equal groups. (1) Stable noise group: exposed to 110 dBA stable noise for 3 days, 4 hours per day. (2) Impulse noise group: exposed to 165 dBA simulated cannon fire impulse noise 10 times successively at an interval of 10 seconds. (3) stable plus impulse noise group: exposed to the same stable noise as that in the first group, then after a 2-hour rest, the animals were followed with impulse noise exposures as that in the second group. After those exposure, each of the 3 groups was further divided into 4 subgroups according to the time after the noise exposure, namely, the right after, 7 d, 14 d and 30 d groups. The evoked cortical potential responses to click and tone burst stimulation sound were examined. The surface preparation and celloidine embedded serial section of the cochlea were observed under a light microscope. RESULTS: Both the stable and impulse noise could increase the hearing threshold and damage the inner ear hair cells. The damage in the first group was relatively slight, whereas in group 3 the damage was more severe than that in the other 2 groups. CONCLUSION: For seamen who are working in heavy noise environment, corresponding measures should be taken to protect their ears from noise which induces hearing loss.

Animals↗
PubMedDate not supplied

Does health promotion work in relation to noise?

Noise is a health risk. The only scientifically established adverse health effect of noise is noise-induced hearing loss (NIHL). Besides noise may affect quality of life and cause annoyance and sleep disturbance. The present scientific evidence of potential non-auditory effects of noise on health is quite weak. Whether health promotion works in relation to noise may be reflected by permanent hearing threshold shift development in population studies. Hearing impairment continues to be the most prevalent disability in Western societies. The National Institute of Occupational Safety and Health (NIOSH) still rates noise induced hearing loss among the top ten work-related problems. Recent studies report that employees continue to develop noise induced hearing loss although to a lesser extent than before, in spite of occupational hearing conservation programmes. Besides socio-acusis and leisure noise seem to be an increasing hazard to hearing, also in young children and adolescents. This seems partly related to acute leisure noise exposure (e.g. toy pistols, amplified music). However, population studies increasingly find non-normal high-frequency hearing including the characteristic NIHL-"notch" around 6 kHz also in subjects who do not report noise exposure incidents or activities. Today 12.5% of US children 6-19 years show a noise-"notch" in one or both ears (n= 5249, Niskar et al 2001). A Norwegian county audiometry survey on adults >/= 20 years n=51.975) showed mean unscreened thresholds +10 dB at 6 kHz for both genders even or the youngest age group 20-24 years (Borchgrevink et al 2001). Accordingly, the present health promotion initiatives seem insufficient in relation to noise and noise-induced hearing loss.

Adolescent↗
PubMedDate not supplied

Impulse noise and risk criteria.

Impulse noise causes evidently more severe hearing loss than steady state noise. The additional effect of occupational impulse noise on hearing has been shown to be from 5 to 12 dB at 4 kHz audiometric frequency. Reported cases for compensated for hearing loss are prevalent in occupations where noise is impulsive. For impulse noise two measurement methods have been proposed: the peak level method and energy evaluation method. The applicability of the peak level method is difficult as even the recurrent impulses have different time and frequency characteristics. Various national risk criteria differ from international risk criteria. In France the maximum A-weighted peak level is 135 dB, and in the United Kingdom the C-weighted peak sound pressure is limited to 200 Pa (140 dB). This criterion of unweighted 200 Pa (140 dB) is used in European Union (EU) directive 86/188 and ISO 1999-1990 regardless of the number of impulses. The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that no exposure in excess of a C-weighted peak sound pressure level of 140 dB should be permitted. At work places these norms do not cause any practical consequences since the impulses seldom exceed 140 dB peak level. In several occupations the impulses are so rapid that they contribute only a minimal amount to the energy content of noise. These impulses can damage the inner ear even though they cause reduced awareness of the hazard of noise. Based to the present knowledge it is evident that there is the inadequacy of the equal energy principle in modelling the risk for hearing loss. The hearing protectors attenuate industrial impulse noise effectively due to the high frequency contents of impulses. Directive regarding the exposure of workers to the risks arising from noise requires that in risk assessment attention should be paid also to impulsive noise. So far there is no valid method to combine steady state and impulse noise. A statistical method for the measurements of industrial impulse noise is needed to get a preferably single number for risk assessment. There is an urgent task to develop risk assessment method and risk criteria for impulsive noise to meet the requirements of the upcoming European Union noise directive.

Adult↗
PubMed2004

Noise overstimulation induces immediate early genes in the rat cochlea.

In mammals, exposure to intense noise produces a permanent hearing loss called permanent threshold shift (PTS), whereas a moderate noise produces only a temporary threshold shift (TTS). Little is known about the molecular responses to such high intensity noise exposures. In this study we used gene arrays to examine the early response to acoustic overstimulation in the rat cochlea. We compared cochlear RNA from noise-exposed rats with RNA from unexposed controls. The intense PTS noise induced several immediate early genes encoding both transcription factors (c-FOS, EGR1, NUR77/TR3) and cytokines (PC3/BTG2, LIF and IP10). In contrast, the TTS noise down-regulated the gene for growth hormone. The response of these genes to different noise intensities was examined by quantitative RT-PCR 2.5 h after the 90-min noise exposure. For most genes, the extent of induction correlates with the intensity of the noise exposure. Three proteins (EGR1, NUR77/TR3, and IP10) were detected in many regions of the unexposed cochlea. After exposure to 120 dB noise, these proteins were present at higher levels or showed extended expression in additional regions of the cochlea. LIF was undetectable in the cochlea of unexposed rats, but could be seen in the organ of Corti and spiral ganglion neurons following noise. NUR77/TR3 was a nuclear protein before noise, but following noise translocated to the cytoplasm. These studies provide new insights into the molecular response to noise overstimulation in the mammalian cochlea.

Acoustic Stimulation↗
PubMed1997

Effects of combined exposure to noise and toxic substances--critical review of the literature.

A number of studies have been conducted in recent years investigating the potential effects on various health endpoints of the combination of noise and a variety of different industrial substances. This review indicates that the information available in both animals and humans on this subject is limited particularly with respect to assessing occupational risk. Most studies have focused on auditory effects in animals, although investigations have been performed for other toxicological endpoints. For some substances, notably toluene, the information from animals studies does suggest an interaction but these were performed only at exposure levels to both noise and chemicals which were each individually ototoxic. Single simultaneous exposure to noise and styrene did not result in any enhancement of auditory impairment above that produced by noise or styrene alone. Single simultaneous exposure to noise and carbon monoxide (CO), however, showed some evidence of enhancement of ototoxicity beyond that produced by noise or carbon monoxide alone, although only at high atmospheric concentrations of CO. When 1,3-dinitrobenzene was administered parentally at neurotoxic dose levels with continuous noise exposure, there was an increased severity of effects in the brain stem. Combined exposure to noise and lead and/or cadmium resulted in histopathological heart lesions of undefined severity, a finding which was not observed for either of those agents in isolation. Dermal exposure to dimethylformamide and noise or inhalation exposure to xylene and noise resulted in some biochemical changes in cardiac muscle which were of doubtful toxicological significance. In developing mice, there was evidence that combined exposure to cadmium sulphate and noise caused an increased incidence of external and skeletal malformations but only at dose levels of cadmium which would have induced developmental effects. Overall, for each of these chemicals and endpoints observed there is a suggestion of some interaction with noise exposure. From the data that are currently available, however, inferences cannot be drawn on whether or not interactions would have occurred at lower, more occupationally relevant, levels of exposure. A number of studies have investigated human populations exposed to both noise and industrial chemicals. Due to confounding factors, however, it was concluded that these data were inadequate for assessing the combined effects of noise and chemical exposure on hearing.

Animals↗
PubMed1997

Basilar membrane velocity noise.

Basilar membrane (BM) noise, measured as a velocity signal under the quiet acoustic condition, was investigated in the guinea pig. The cochleas of anesthetized young healthy guinea pigs were surgically exposed and a hole was made on the lateral wall of the scala tympani of the first cochlear turn for visualization of the BM and measurement of the BM velocity with a laser interferometer. The amplitude and frequency of the BM velocity noise were analyzed by a spectrum analyzer under different conditions. The spectrum of the BM velocity noise was a band limited function with a peak velocity at the topographic best frequency of the measured location on the BM. The peak velocity ranged to about 8 microm/s and depended on the physiological condition of the cochlea. Saline blockage of the external auditory canal or the middle ear did not change the BM noise. BM noise was much smaller, or was not evident, when the cochlear sensitivity decreased. The suppression tuning curve of the BM velocity noise indicates that the maximum suppression caused by an acoustic pure tone occurred at the best frequency location. A low sound level wide band acoustic noise given to the external ear canal produced a spectrum function having the same frequency and amplitude response as the BM noise. Electrical stimulation of the crossed olivocochlear bundle significantly depresses the BM velocity noise. These data demonstrate that the BM noise is a representation of internal rather than external noise. The amplitude and frequency of the BM noise reflect the usual cochlear sensitivity and frequency selectivity. Since the organ of Corti in the sensitive cochlea is a highly sensitive and tuned mechanical system, the internal (to the animal) noise responsible for the BM noise may originate from mechanical vibrations remote from the cochlea and propagated to the ear, or may be caused by Brownian motion of cellular structures in the cochlea.

Acoustic Stimulation↗
PubMed1999

Intermittent noise-induced hearing loss and the influence of carbon monoxide.

Intermittent noise causes less hearing loss than continuous noise of equal intensity. The reduction in damage observed with intermittent noise may be explained by the fact that the auditory system has time to recover between the noise phases. Simultaneous carbon monoxide (CO) exposure produces greater noise-induced hearing loss than does noise alone (Chen and Fechter, 1999). In the present study, intermittent noise (octave-band with a center frequency of 13.6 kHz, 100 dB) of a 2 h total duration but with a different duty cycle (% of noise during exposure) was used. The intermittent exposure that had a shorter noise duty cycle induced a less permanent threshold shift (PTS) than those that had a longer noise duty cycle (or less rest periods). This relation between the loss in compound action potential (CAP) sensitivity and the noise duty cycle (or rest period) was abolished by the presence of CO. The cochlear microphonic (CM) amplitude revealed similar results to those seen using the CAP. While intermittent noise that had a short noise duty cycle did not cause hair cell loss by itself, the combined exposure to noise and CO (1200 ppm) caused remarkable OHC loss in the basal turn.

Action Potentials↗
PubMed1984

Masking-level difference in filtered-random and amplitude-modulated noise.

The masking characteristics of filtered-random noise and amplitude-modulated noise (40-dB pressure-spectrum level) were studied in a series of four experiments using a masking-level difference paradigm, that is, 500-Hz thresholds in S0N0 and SpiN0 binaural conditions. In Experiment 1 a filtered noise (200-800 Hz) and an amplitude-modulated noise (425-575 Hz) produced equal thresholds in S0N0; for SpiN0, however, the thresholds in amplitude-modulated noise were 1.6 dB lower than were the thresholds in filtered noise. In Experiment 2 S0N0 and SpiN0 thresholds were established in three filtered noise bandwidths (200-800 Hz, 335-685 Hz, and 410-600 Hz) and in the amplitude-modulated noise (425-575 Hz). When the bandwidths of the filtered-random and amplitude-modulated noises were similar, the SpiN0 thresholds were the same but the S0N0 thresholds were different. Experiments 3 and 4 indicated that with amplitude-modulated noise when the zero amplitude crossings of the tone and the noise coincided, the S0N0, SpiN0, and SmNm thresholds were 1.2-2.0 dB higher than were the thresholds when the zero crossings of the tone and noise did not coincide. The data indicate that the masking characteristics of filtered-random noise and amplitude-modulated noise are different. The findings are interpreted as an indication that perceptual phenomena depend on the temporal characteristics as well as the power spectrum of the signal and masker.

Adult↗
PubMed2004

The accuracy of self-reported high noise exposure level and hearing loss in a working population in Eastern Saudi Arabia.

OBJECTIVE: To determine the accuracy of questions in identifying subjects occupationally exposed to high noise level and those with hearing loss using noise dosimeter and pure-tone air conduction audiometry as the gold standards. DESIGN: A cross-sectional study involving 259 noise-exposed workers selected randomly from two factories in Eastern Saudi Arabia. Personal noise exposure was determined using a noise dosimeter. The hearing impairment for each subject was assessed using otoscopic examination and audiometry. Each subject completed a comprehensive questionnaire including questions about noise exposure and hearing loss. RESULTS: Eighty five percent of the total workers reported exposure to high noise level, compared to 76% found to be exposed to a high noise level defined as more than 85 dB (A) as determined by noise dosimeter. The prevalence of audiometric hearing loss (threshold average of 25 dB HL or more in any ear) was 32.4% for the low frequency average (0.5, 1 and 2 kHz), 47.9% for the all frequency average (0.5, 1, 2. 4 and 8 kHz) and 65.6% for the high frequency average (4 and 8 kHz). However, the percentage of the subjects who reported hearing loss ranged between 3.9% and 85.3% depending on the question used as indicator of hearing loss. The question "Do you consider the noise level where you are working now high?" was the most sensitive in correctly identifying subjects exposed to a noise level of more than 85 dB (A) (sensitivity = 93.4%) and subjects with hearing loss (sensitivity > 86%) compared with other questions evaluated. However, it overestimated the prevalence rate determined by audiometry. CONCLUSION: We conclude that in industries where facilities for an objective assessment of noise exposure and hearing loss are not available, questions addressing noise exposure and hearing loss might be a useful alternative means for screening subjects exposed to high noise level and those with hearing loss for the purpose of designing and implementing hearing conservation program.

Adult↗
PubMed1990

Noise exposure reduction aboard an oceangoing hopper dredge.

Reported industrial hygiene surveys aboard seagoing vessels are few, despite the presence of many potentially hazardous chemical and physical agents aboard ships. This investigation focused on crew noise exposure aboard an oceangoing hopper dredge. Noise exposure criteria were adopted based on the 24-hr equivalent continuous sound level (Leq(24)) because of the absence of standards for U.S. shipboard noise exposure. Personal noise dosimeters were used to measure the noise exposure of watchstanders, whose duties were predictable and repetitive. Watchstanders with high noise doses were asked to estimate their duration of exposure in specific areas of the vessel to enable calculation of noise dose per space. Noise sources within spaces associated with high noise dose were identified by sound pressure and surface vibration analysis in octave bands. Almost all accommodation spaces (cabins, recreation rooms, dining rooms, and hospital) were sufficiently quiet (sound pressure levels [SPLs] less than 65 dBA) to permit hearing threshold recovery. Machinery space SPLs ranged from 85 to 108 dBA, and engineering personnel noise exposure exceeded the selected criterion of Leq(24) = 80 dBA. Selective noise abatement and use of an enclosed operating station in the engine room were recommended to control engineering personnel noise exposure. This approach to noise exposure assessment and reduction should be applicable to other oceangoing ships where personnel may be exposed to noise 24 hr per day for weeks at a time.

Engineering↗
PubMed2007

Speech understanding in background noise with the two-microphone adaptive beamformer BEAM in the Nucleus Freedom Cochlear Implant System.

OBJECTIVE: This paper evaluates the benefit of the two-microphone adaptive beamformer BEAM in the Nucleus Freedom cochlear implant (CI) system for speech understanding in background noise by CI users. DESIGN: A double-blind evaluation of the two-microphone adaptive beamformer BEAM and a hardware directional microphone was carried out with five adult Nucleus CI users. The test procedure consisted of a pre- and post-test in the lab and a 2-wk trial period at home. In the pre- and post-test, the speech reception threshold (SRT) with sentences and the percentage correct phoneme scores for CVC words were measured in quiet and background noise at different signal-to-noise ratios. Performance was assessed for two different noise configurations (with a single noise source and with three noise sources) and two different noise materials (stationary speech-weighted noise and multitalker babble). During the 2-wk trial period at home, the CI users evaluated the noise reduction performance in different listening conditions by means of the SSQ questionnaire. In addition to the perceptual evaluation, the noise reduction performance of the beamformer was measured physically as a function of the direction of the noise source. RESULTS: Significant improvements of both the SRT in noise (average improvement of 5-16 dB) and the percentage correct phoneme scores (average improvement of 10-41%) were observed with BEAM compared to the standard hardware directional microphone. In addition, the SSQ questionnaire and subjective evaluation in controlled and real-life scenarios suggested a possible preference for the beamformer in noisy environments. CONCLUSIONS: The evaluation demonstrates that the adaptive noise reduction algorithm BEAM in the Nucleus Freedom CI-system may significantly increase the speech perception by cochlear implantees in noisy listening conditions. This is the first monolateral (adaptive) noise reduction strategy actually implemented in a mainstream commercial CI.

Adult↗
PubMed2002

Evaluation of a noise reduction system for the assessment of click-evoked otoacoustic emissions.

A recently proposed noise reduction system intended to facilitate the assessment of click-evoked otoacoustic emission (CEOAE) in noisy environments [Comput. Biol. Med. 30, 341 (2000)] is evaluated using 13 normally hearing ears and 9 ears with a sensorineural hearing loss. The noise reduction system is based on an adaptive noise canceller design using an additional noise-only reference microphone and intended to reduce externally generated noise. The system is tested in quiet and at different levels of white noise. The three main design parameters of the noise reduction system (adaptation time constant, length of the adaptive filter, and position of the noise reference microphone) are varied systematically in different experiments. With the noise reduction system active, CEOAE can be assessed correctly at noise levels which are 5 to 9 dB higher than without the noise reduction system. For the range of adaptation time constants considered (65.6 to 656 ms), no statistically significant effect on the amount of noise reduction is observed. Noise reduction is highest when the reference microphone is positioned close to the ear probe. Using this reference microphone position and adaptive filters of 6.56 ms in length, average noise reductions of 7.17 to 8.50 dB are achieved.

Acoustic Stimulation↗
PubMed1997

Noise adaptation in integrate-and fire neurons.

The statistical spiking response of an ensemble of identically prepared stochastic integrate-and-fire neurons to a rectangular input current plus gaussian white noise is analyzed. It is shown that, on average, integrate-and-fire neurons adapt to the root-mean-square noise level of their input. This phenomenon is referred to as noise adaptation. Noise adaptation is characterized by a decrease in the average neural firing rate and an accompanying decrease in the average value of the generator potential, both of which can be attributed to noise-induced resets of the generator potential mediated by the integrate-and-fire mechanism. A quantitative theory of noise adaptation in stochastic integrate-and-fire neurons is developed. It is shown that integrate-and-fire neurons, on average, produce transient spiking activity whenever there is an increase in the level of their input noise. This transient noise response is either reduced or eliminated over time, depending on the parameters of the model neuron. Analytical methods are used to prove that nonleaky integrate-and-fire neurons totally adapt to any constant input noise level, in the sense that their asymptotic spiking rates are independent of the magnitude of their input noise. For leaky integrate-and-fire neurons, the long-run noise adaptation is not total, but the response to noise is partially eliminated. Expressions for the probability density function of the generator potential and the first two moments of the potential distribution are derived for the particular case of a nonleaky neuron driven by gaussian white noise of mean zero and constant variance. The functional significance of noise adaptation for the performance of networks comprising integrate-and-fire neurons is discussed.

Acclimatization↗
PubMed1990

Selective hearing in the aged with regard to speech perception in quiet and in noise.

Most listening environments contain some noise which is mixed up with the speech. The effects of noise on speech perception depend on the parameters of the noise (long term spectrum, fluctuations of the intensity in time and average intensity relative to the intensity of speech) and on the speech material (sentences, monosyllables, CV-, CVC-, VC-syllables). The most effective at masking are noises with spectra similar to the speech spectrum, such as the speech simulating noise (CCITT-noise) or cocktail-party-noise. The cocktail-party situation is judged to be a difficult communication situation not only by the hearing impaired but also by patients with presbycusis. We examined different age-dependent changes of the speech discrimination in noise ability. Using sentences and CV-syllables (rhyme test) the critical signal-to-noise ratios (S/N-dB) for a speech discrimination of 35%-45% were investigated for monaural and binaural noise representations for different age groups. The results are compared to several types of hearing loss and to those of similar studies in literature. The data of this study prove that hearing impaired and elderly patients are greatly affected by noise. While younger patients with moderate high-tone hearing loss may profit from a special hearing aid device with an integrated noise suppression-system, an improvement of speech discrimination in noise for the elderly can be achieved only by enhancing the signal-to-noise ratio by more than 10 dB. This is possibly because of the reduced capacity for frequency-, intensity- and time-resolution in the peripheral and central pathways of the hearing organ of the aged.

Adult↗
PubMed1976

[A trial measurement of individual noise exposure by time-zone in a day (author's transl)].

Noise has been measured usually for a particular source or place and not for each individual exposed. It has been thought to be of great significance if individual noise exposure is recorded in various kinds of noise environment and auditory effects of noise on each individual can be discussed. The present study, having each of examinees carry 10-Channel Noise Exposure Meter with him, intended to know about dose or equivalent sound level (Leq) of individual nois exposure for a whole day and for each of eight time-zones in a day. The examinees were 12 male married workers in a factory manufacturing electronic machines in Kawasaki City, Kanagawa Prefecture, Japan. They were divided into two groups; those who were working in a noisy workshop (Group N, 8 workers) and those who were working in a less noisy workshop (Group N-N 4 workers). Time-zones were categorized as follows: (a) time from rising to leaving home for the place of work, (b) commuting time in the forenoon, (c) working time in the forenoon, (d) noon recess time, (e) working time in the afternoon, (f) commuting time in the afternoon, (g) time from returning home to going to bed, and (h) sleeping time. Leq (c) and Leq (b) were highest and Leq (h) was lowest for Group N among the eight Leq values in the day, while Leq (b) and Leq (f) were highest for Group N-N. Statistically significant differences of Leq for each time-zone between the two groups were found in Leq (c), Leq (d) and Leq (e), whose energy average sound levels for Group N and Group N-N were 84.2 and 59.4 dB, 72.7 and 61.4 dB, and 85.5 and 61.4 dBrespectively. Energy average equivalent sound levels of Leq (24) were 81.0 dB for Group N and 66.7 dB for Group N-N. Leq (24) for Group N were primarily determined by the noise exposure in the working time (c and e), while those for Group N-N by that in the commuting time (b and f). Practical disadvantages in the course of individual application of 10-Channel Noise Exposure Meter were also pointed out. It was shown that it is possible individually to measure the noise exposure dose for each time-zone in a day or daily noise exposure pattern, and the noise exposure dose over 24-hour. It may be recommended that many typical noise exposure patterns and 24-hour noise exposure doses for each of the groups classified by sex, age, kind of job, kind of commuting methods, kind of residential area of residential area and so forth should be surveyed further, which will be useful for estimating the auditory effects of noise on a population. Also, the relationships between Leq and such effects as annoyance or interference with daily activities should be examined to ease the measurement of noise.

Adult↗
PubMed2000

[A field study of health effects of aircraft noise in adults around Komatsu Air Base (1998)].

OBJECTIVE: To ascertain the effects of aircraft noise on complaints about life disturbances and on psychological and physical symptoms in adults around Komatsu air base. METHODS: From April to June 1998, a questionnaire was answered by 203 persons (from 89.8% of families) in 2 areas without aircraft noise, and by 412 persons (from 89.0% of families) in 5 areas with a weighted equivalent continuous perceived noise level (WECPNL) of 75 or more. The questionnaire covered age, gender, work location, noise exposure time, past experience with noisy work and ear disease, complaints about noisiness and life disturbances, and psychological and physical symptoms. Multivariate linear models by JMP (SAS institute Inc.) were applied to analyze the relationships between the above factors including noise level and complaints or symptoms. RESULTS: Subjects in the areas with noise had more complaints about noisiness than 5 years before, although replies were less in areas without noise. Subjects in areas with a WECPNL of 75 or more had more complaints and symptoms than those in areas without noise. Moreover, subjects experiencing higher noise levels gave higher responses for most of complaints and symptoms. The JMP linear models showed that aircraft noise was positively related to complaints and symptoms after taking the effects of age, gender and past experience with noisy work and ear disease into consideration. Higher noise levels and longer exposure times were related more strongly to most complaints and symptoms. CONCLUSION: This study shows that aircraft noise with a WECPNL of 75 or more is related to various complaints and psychological and physical symptoms in adults around Komatsu air base, after considering the effects of age, gender and past experience with noisy work and ear disease. It also shows that higher noise levels and longer exposure times are related more strongly to many complaints and symptoms. The results also suggest that responses to aircraft noise have become more severe than in the past.

Adult↗