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PubMed2001

Age and noise-induced hearing loss.

The purpose of the study was to evaluate the effect of noise, age and confounders in noise-induced hearing loss (NIHL). Information about work exposure, the use of hearing protective devices, audiogram, environmental and biological factors was collected from 406 paper mill workers exposed to noise levels of 91-94 dB(A), 124 forest workers exposed to noise levels of 96-99 dB(A) and 176 shipyard workers exposed to noise levels 95-97 dB(A). In addition to noise exposure, we collected the following confounders: smoking habits, serum cholesterol, systolic or diastolic blood pressure and use of analgesics. Subjects were classified based on median values, into high- and low-risk groups. The confounders were a significant source of hearing loss (HL) in younger and elderly groups of subjects, serum cholesterol level being the most important. In risk analysis the confounders partly masked the effects of noise in the development of HL. For subjects with less than two confounders, occupational noise exposure determined the development of NIHL. As the number of confounders increased, the noise exposure was overruled by these factors in the development of HL. In analysis where the subjects were matched with pairs by age, exposure, blood pressure and serum cholesterol level, the elderly subjects were more susceptible to NIHL than younger subjects. Factors independently but causally related to age were important in the development of NIHL among workers exposed to noise levels below 98 dB(A).

Adult↗
PubMed1995

Prediction of traffic noise: a screening technique.

Traffic noise is ubiquitous in many communities and is an important environmental concern, especially for persons located near major roadways. Several different methods are available to estimate noise levels resulting from roadway traffic. These include computational, graphical, and computer modeling techniques. The prediction methodology presented here is a simplified technique that can be used for estimating noise resulting from traffic and for screening traffic noise impacts. This Traffic Noise Screening (TNS) approach consists of a series of traffic noise level prediction graphs developed for different roadway configurations. The graphs are based on the results from using the Federal Highway Administration (FHWA) STAMINA2.0 computerized noise prediction model for various scenarios. Data inputs to the TNS approach include roadway genometries, traffic volumes, vehicle travel speed, and centerline distance to the receptors. The TNS graphs allow easy estimation of traffic noise levels for use in predicting traffic-related noise impacts. This TNS approach is not intended as a substitute for detailed modeling, such as with STAMINA2.0, but as a screening tool to aid in determining when detailed modeling may be necessary. If screening results indicate that noise estimates are significant, or if the scenario is rather complex, then additional, more detailed modeling can be performed.

Automobiles↗
PubMed2006

The role of silent intervals for sentence intelligibility in fluctuating noise in hearing-impaired listeners.

Fluctuating interfering noises are highly suitable for speech audiometry because of the large inter-individual variability in intelligibility results. This study explores the maximum duration of silent intervals in the masker as an important factor underlying sentence intelligibility in fluctuating noise. Three versions of speech-simulating fluctuating interfering noises based on the icra noises (Dreschler et al, 2001) were explored: The original noise which simulates one interfering speaker and contains pause durations up to two seconds, as well as two modified versions with pause durations limited to 250 ms and 62.5 ms, respectively. In addition, a stationary speech-shaped noise was used. Test-retest reliability as well as speech reception threshold (SRT) and speech intelligibility function slope were determined with hearing-impaired subjects. All fluctuating noises differentiated very well between subjects. Partial rank correlation analysis showed that SRTs in fluctuating noise with longest maximum pause durations mostly depended on SRTs in quiet. SRTs in fluctuating noises with smaller maximum pause durations correlated both with SRTs in quiet and in stationary noise.

Acoustic Stimulation↗
PubMed2005

Exposure-effect relations between aircraft and road traffic noise exposure at school and reading comprehension: the RANCH project.

Transport noise is an increasingly prominent feature of the urban environment, making noise pollution an important environmental public health issue. This paper reports on the 2001-2003 RANCH project, the first cross-national epidemiologic study known to examine exposure-effect relations between aircraft and road traffic noise exposure and reading comprehension. Participants were 2,010 children aged 9-10 years from 89 schools around Amsterdam Schiphol, Madrid Barajas, and London Heathrow airports. Data from The Netherlands, Spain, and the United Kingdom were pooled and analyzed using multilevel modeling. Aircraft noise exposure at school was linearly associated with impaired reading comprehension; the association was maintained after adjustment for socioeconomic variables (beta = -0.008, p = 0.012), aircraft noise annoyance, and other cognitive abilities (episodic memory, working memory, and sustained attention). Aircraft noise exposure at home was highly correlated with aircraft noise exposure at school and demonstrated a similar linear association with impaired reading comprehension. Road traffic noise exposure at school was not associated with reading comprehension in either the absence or the presence of aircraft noise (beta = 0.003, p = 0.509; beta = 0.002, p = 0.540, respectively). Findings were consistent across the three countries, which varied with respect to a range of socioeconomic and environmental variables, thus offering robust evidence of a direct exposure-effect relation between aircraft noise and reading comprehension.

Aircraft↗
PubMed2003

Noise pollution: non-auditory effects on health.

Noise is a prominent feature of the environment including noise from transport, industry and neighbours. Exposure to transport noise disturbs sleep in the laboratory, but not generally in field studies where adaptation occurs. Noise interferes in complex task performance, modifies social behaviour and causes annoyance. Studies of occupational and environmental noise exposure suggest an association with hypertension, whereas community studies show only weak relationships between noise and cardiovascular disease. Aircraft and road traffic noise exposure are associated with psychological symptoms but not with clinically defined psychiatric disorder. In both industrial studies and community studies, noise exposure is related to raised catecholamine secretion. In children, chronic aircraft noise exposure impairs reading comprehension and long-term memory and may be associated with raised blood pressure. Further research is needed examining coping strategies and the possible health consequences of adaptation to noise.

Cardiovascular Diseases↗
PubMed1990

Comparison of cardiovascular responses to noise during waking and sleeping in humans.

Eighty subjects, 40 men and 40 women, were allocated to one of two groups according to their self-estimated high or low sensitivity to noise. In the first part of the experiment, they were exposed to sequences of common noises during the morning or the afternoon. The heart-rate and finger-pulse responses were measured and recorded in relation to sensitivity, sex of subjects, and time of day. The different types of noise were compared for both responses. The heart-rate response showed differences between sensitivity groups but not between noises. In contrast, no significant differences were obtained between sensitivity groups when using the finger-pulse response, but clear differences were observed between noises. In a second part of the experiment, 10 men and 10 women subjects were selected from the previous two sensitivity groups. These 20 subjects were exposed during sleep to the same noises as during the daytime. Heart-rate and finger-pulse responses during sleep were significantly greater than during waking, and they did not differ significantly with respect to sensitivity to noise or gender. These two autonomic responses showed differences between noises that appeared to be related to their noise-equivalent-level value. Compared with the silent baseline night, the sleep pattern showed no significant modification in the night of noise disturbance, except for the frequency of transient activation phases, which was significantly increased in the latter.

Adult↗
PubMed2000

Use of active noise cancellation devices in caregivers in the intensive care unit.

OBJECTIVE: Recent development of noise cancellation devices may offer relief from noise in the intensive care unit environment. This study was conducted to evaluate the effect of noise cancellation devices on subjective hearing assessment by caregivers in the intensive care units. DESIGN: Randomized, double-blind. SETTING: Adult medical intensive care unit and pediatric intensive care unit of a teaching hospital. SUBJECTS: Caregivers of patients, including nurses, parents, respiratory therapists, and nursing assistants from a medical intensive care unit and pediatric intensive care, were enrolled in the study. INTERVENTION: Each participant was asked to wear the headphones, functional or nonfunctional noise cancellation devices, for a minimum of 30 mins. MEASUREMENTS: Subjective ambient noise level was assessed on a 10-point visual analog scale (VAS) before and during headphone use by each participant. Headphone comfort and the preference of the caregiver to wear the headphone were also evaluated on a 10-point VAS. Simultaneously, objective measurement of noise was done with a sound level meter using the decibel-A scale and at each of nine octave bands at each bedspace. RESULTS: The functional headphones significantly reduced the subjective assessment of noise by 2 (out of 10) VAS points (p < 0.05) in environments of equal objective noise profiles, based on decibel-A and octave band assessments. CONCLUSION: Noise cancellation devices improve subjective assessment of noise in caretakers. The benefit of these devices on hearing loss needs further evaluation in caregivers and critically ill patients.

Adult↗
PubMedDate not supplied

Effects of noise on NST and NU 6 stimuli.

This study determined how normal-hearing listeners' performance on a nonsense syllable test (NST) was affected by three noise competitors, and how these responses differed from those on the standard NU 6 meaningful word test. Twenty young adult listeners heard the stimuli via earphones and provided verbal responses to the NST and NU 6 items in competition with: white noise, multitalker noise, and white noise which was amplitude modulated by the multitalker noise, each at a 0 dB signal-to-noise ratio. Responses were scored on a whole-word (all-or-none) basis. Statistical analyses revealed that listeners' performance was always poorer on the NST than on the NU 6 regardless of competitor type; and that scores were better in the multitalker noise followed by white noise and amplitude modulated white noise. These data and those from earlier studies indicate that the NST is sufficiently difficult in quiet that it may not warrant testing in noise.

Adolescent↗
PubMed2001

Effects of the number of channels and speech-to-noise ratio on rate of connected discourse tracking through a simulated cochlear implant speech processor.

OBJECTIVE: To investigate the effects of number of channels and speech-to-noise ratio on connected discourse tracking (CDT) through simulations of cochlear implant speech processing. Previous studies have used citation-form vowel and consonant materials or simple sentences. CDT rates were expected to be less likely to be limited by ceiling effects and more representative of everyday speech communication. DESIGN: Four normal-hearing subjects were presented with speech processed through a real-time sine-excited vocoder having three, four, eight, or 12 channels. Amplitude envelopes extracted from each band modulated sinusoidal carrier signals placed at each band center frequency. Speech-spectrum shaped noise was added to speech before vocoder processing at three signal to noise ratios based on real-time measurements of speech level (+7, +12, +17 dB). RESULTS: CDT rates increased significantly with number of channels up to eight in both quiet and noise, and decreased significantly with each increase in noise level from quiet. CONCLUSIONS: The effects on CDT rates of the number of channels and speech-to-noise ratio are highly correlated with intelligibility measures for Hearing in Noise Test (HINT) sentences, consonants and vowels. However, HINT sentence scores even in noise show ceiling effects that obscure the advantages of processors with eight or more channels. Moderate levels of noise that have only slight effects on other measures significantly affected CDT rate. CDT rates with three or four bands of spectral information were much lower than asymptotic rates, especially in the presence of noise.

Acoustic Stimulation↗
PubMed1998

Occupational noise-induced hearing loss surveillance in Michigan.

Occupational noise-induced hearing loss (NIHL) is an important yet often overlooked illness that can affect an individual's safety and performance at work. This article describes a state-based surveillance system for occupational NIHL. The Michigan surveillance system enables us to describe the magnitude of occupational NIHL among Michigan workers and direct public health interventions in the form of enforcement workplace inspections. The data presented are based on interviews of individuals with occupational NIHL reported to the Michigan Department of Consumer and Industry Services (MDCIS) by Michigan's audiologists and otolaryngologists from 1992-1997. From 1992-1997, 1378 individuals with occupational NIHL were reported to the MDCIS and interviewed about their exposures to noise at work. Over 70% of the workplace noise exposure were in manufacturing. At the most recent company where these individuals were exposed to noise, approximately 46% were not provided regular hearing testing. Regular hearing testing was more likely to occur in the larger companies and in industries covered by regulations requiring such testing to be performed. There were improvements over time in the percentages of companies providing regular hearing testing and hearing protection. Construction workers are employees among a group of industries that are not adequately protected from excessive noise exposures by occupational regulations. Regular hearing testing was not provided for over 90% of construction jobs, although hearing protection such as earplugs or earmuffs was provided for approximately half of these jobs. Forty-three state enforcement inspections were conducted at the companies reported by the patients interviewed, because these companies were reported to provide no regular hearing testing or no hearing protection despite exposures to excessive levels of noise. During the 43 inspections, 23 companies had noise levels above dBA, and 17 of those had either no hearing conservation program (HCP) or had one that was cited as being incomplete. The inspections potentially protected 758 similarly exposed workers in the companies with the high noise levels that lacked an HCP or that had a deficient HCP. The number of patients with occupational NIHL is likely a gross underestimate of the true magnitude of the disease. However, the surveillance system has identified workplaces with hazardous levels of noise and no HCP, thereby protecting similarly exposed coworkers of the index patients from further exposures to noise and hearing loss.

Ear Protective Devices↗
PubMed1997

Population dynamics and the colour of environmental noise.

The effect of red, white and blue environmental noise on discrete-time population dynamics is analyzed. The coloured noise is superimposed on Moran-Ricker and Maynard Smith dynamics, the resulting power spectra are less than examined. Time series dominated by short- and long-term fluctuations are said to be blue and red, respectively. In the stable range of the Moran-Ricker dynamics, environmental noise of any colour will make population dynamics red or blue depending the intrinsic growth rate. Thus, telling apart the colour of the noise from the colour of the population dynamics may not be possible. Population dynamics subjected to red and blue environmental noises show, respectively, more red or blue power spectra than those subjected to white noise. The sensitivity to differences in the noise colours decreases with increasing complexity and ultimately disappears in the chaotic range of the population dynamics. These findings are duplicated with the Maynard Smith model for high growth rates when the strength of density dependence changes. However, for low growth rates the power spectra of the population dynamics with noise are red in stable, periodic and aperiodic ranges irrespective of the noise colour. Since chaotic population fluctuations may show blue spectra in the deterministic case, this implies that blue deterministic chaos may become red under any colour of the noise.

Acoustics↗
PubMed2000

Adaptive noise cancellation in a multimicrophone system for distortion product otoacoustic emission acquisition.

This study focuses on adaptive noise cancellation (ANC) techniques for the acquisition of distortion product otoacoustic emissions (DPOAEs). Otoacoustic emissions (OAEs) are very low level sounds produced by the outer hair cells of normal cochleas, spontaneously or in response to sound stimulation as a byproduct of a frequency and threshold sensitivity increasing mechanism. Current OAE recording systems rely on test probe noise attenuation and synchronous ensemble averaging for increasing signal-to-noise ratios (SNRs). The efficiency of an ANC algorithm for noise suppression was investigated using three microphones: one placed in the test ear, one in the nontest ear for internal noise reference; one near the subject's head for external noise reference. The system proposed was tested with simulations, off-line averaging and real-time implementation of the ANC algorithm. Simulation results showed that the technique had a potential noise reduction capability of 24 dB for complex multifrequency noise signals. Off-line results were positive, with a mean SNR improvement of 4.9 dB. Real-time results indicated that the use of an ANC algorithm in combination with standard averaging methods can reduce noise levels by as much as 10 dB beyond that obtained with standard noise reduction methods and probe attenuation alone.

Algorithms↗
PubMed2003

The effects of road traffic noise and meaningful irrelevant speech on different memory systems.

To explore why noise has reliable effects on delayed recall in a certain text-reading task, this episodic memory task was employed with other memory tests in a study of road traffic noise and meaningful but irrelevant speech. Context-dependent memory was tested and self-reports of affect were taken. Participants were 96 high school students. The results showed that both road traffic noise and meaningful irrelevant speech impaired recall of the text. Retrieval in noise from semantic memory was also impaired. Attention was impaired by both noise sources, but attention did not mediate the noise effects on episodic memory. Recognition was not affected by noise. Context-dependent memory was not shown. The lack of mediation by attention, and road traffic noise being as harmful as meaningful irrelevant speech, are discussed in relation to where in the input/storing/output sequence noise has its effect and what the distinctive feature of the disturbing noise is.

Adolescent↗
PubMed2005

Noise levels in a general surgical ward: a descriptive study.

AIMS AND OBJECTIVES: This study was undertaken to measure and analyse levels of acoustic noise in a General Surgical Ward. METHOD: Measurements were undertaken using the Norsonic 116 sound level meter (SLM) recording noise levels in the internationally agreed 'A' weighted scale. Noise level data and observational data as to the number of staff present were obtained and recorded at 5-min intervals over three consecutive days. RESULTS: Results of noise level analysis indicated that mean noise level within this clinical area was 42.28 dB with acute spikes reaching 70 dB(A). The lowest noise level attained was that of 36 dB(A) during the period midnight to 7 a.m. Non-parametric testing, using Spearman's Rho (two-tailed), found a positive relationship between the number of staff present and the level of noise recorded, indicating that the presence of hospital personnel strongly influences the level of noise within this area. RELEVANCE TO CLINICAL PRACTICE: Whilst the results of this may seem self-evident in many respects the problems of excessive noise production and the exposure to it for patients, hospital personnel and relatives alike continues unabated. What must be of concern is the psychophysiological effects excessive noise exposure has on individuals, for example, decreased wound healing, sleep deprivation and cardiovascular stimulation.

England↗
PubMed2004

The effects of meaningful irrelevant speech and road traffic noise on teachers' attention, episodic and semantic memory.

The aim of the present experiment was to examine the effects of meaningful irrelevant speech and road traffic noise on attention, episodic and semantic memory, and also to examine whether the noise effects were age-dependent. A total of 96 male and female teachers in the age range of 35-45 and 55-65 years were randomly assigned to a silent or the two noise conditions. Noise effects found in episodic memory were limited to a meaningful text, where cued recall contrary to expectations was equally impaired by the two types of noise. However, meaningful irrelevant speech also deteriorated recognition of the text, whereas road traffic noise caused no decrement. Retrieval from two word fluency tests in semantic memory showed strong effects of noise exposure, one affected by meaningful irrelevant speech and the other by road traffic noise. The results implied that both acoustic variation and the semantic interference could be of importance for noise impairments. The expected age-dependent noise effects did not show up.

Adult↗
PubMed2004

The effects of moderate heat stress and open-plan office noise distraction on SBS symptoms and on the performance of office work.

UNLABELLED: Three air temperatures (22/26/30 degrees C) and two acoustic conditions-quiet (35 dBA) or open-plan office noise (55 dBA)-were established in an office. Thirty subjects aged 18-29 years (16 male), clothed for thermal neutrality at 22 degrees C, performed simulated office work for 3 h under all six conditions. Many more (68% vs. 4%) were dissatisfied with noise in the noise condition (P < 0.01). Warmth decreased thermal acceptability (P < 0.001) and perceived air quality (P < 0.01) and increased odour intensity (P < 0.05) and stuffiness (P < 0.01). After 2 h, some forehead sweating was observed on 4, 36 and 76% of subjects (P < 0.001) at 22, 26 and 30 degrees C, while 0, 21 and 65% felt "warm" (P < 0.001). Raised temperature increased eye, nose and throat irritation (P < 0.05), headache intensity (P < 0.05), difficulty in thinking clearly (P < 0.01) and concentrating (P < 0.01), and decreased self-estimated performance (P < 0.001). Noise increased fatigue (P < 0.05) and difficulty in concentrating (P < 0.05) but did not interact with thermal effects on subjective perception. In an addition task, noise decreased workrate by 3% (P < 0.05), subjects who felt warm made 56% more errors (P < 0.05) and there was a noise-temperature interaction (P < 0.01): the effect of warmth on errors was less in the noise condition. Typing speed (P < 0.05) and reading speed (P < 0.05) were higher in noise. PRACTICAL IMPLICATIONS: This paper demonstrates that open office noise distraction, even at the realistic level of 55 dBA, increases fatigue and has many negative effects on the performance of office work, as does a moderately warm air temperature. These findings may be used to provide economic justification for the provision of private offices and air temperature control in hot weather. The additional finding that noise distraction and heat stress can sometimes counteract each other in the short term is of academic interest only, as they both increase subjective distress and fatigue. In practice, neither should be deliberately introduced to counteract the other.

Acoustics↗
PubMed1979

Noise and the "rehearsal-masking hypothesis".

This study examines the proposal that continuous loud noise impairs short-term recall by masking the inner speech necessary to rehearse material in memory (Poulton, 1976 a, 1977 b). The "masking hypothesis" contrasts with previous theories which relate recall impairment in noise to the latter's action in over-arousing the individual or inducing changes in attentional deployment. Separate groups performed a visual, serial eight-consonant recall task in either 92 dBA "noise" or 75 dBA "quiet" and in "normal" or "suppressed" rehearsal conditions. The masking hypothesis predicted that noise would impair recall relative to quiet in normal rehearsal conditions. But where the rehearsal of both groups was already suppressed by a concurrent articulatory task, recall would not differ between the groups through noise-masking then being irrelevant. Total correct recall scores appeared to confirm the masking hypothesis but the pattern of serial order recall showed differences between noise and quiet in suppressed rehearsal conditions which seemed better explained by an attentional influence of noise. Further, reduced commission and acoustic confusion errors in noise were not consistent with the predictions of the masking hypothesis. It was concluded that noise-masking could not be refuted but that attentional changes due to the arousing action of noise might also be active determinants of recall.

Adult↗
PubMed1985

Noise, biased probability and serial reaction.

Recent studies have shown that moderate intensity noise does influence performance although most studies showing effects of this level of noise have used verbal materials. An experiment showed that moderate intensity noise (85 dBC) also influences attentional selectivity in a serial reaction task which involved the processing of sensory information. Noise decreased response times to signals with high probabilities of occurrence but increased latencies for signals which occurred less frequently. Although attentional selectivity in noise depended on signal probability, it was not influenced by the spatial location of the signal. When a mode of responding is adopted in noise, subjects are often rather inflexible and continue to use this strategy even though it is inappropriate. This was demonstrated in the present study because the noise-induced bias continued even when the signal probabilities were returned to normal. Previous studies using higher noise intensities have shown that noise often increases the number of errors or gaps. The moderate intensity noise used in the present study did not have this effect.

Attention↗