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PubMed1979

Time-varied noise effects on color-word test performance.

The effects of continuous and time-varied 85 dBA broadband noise on the performance of a Stroop-type color-word test and a related word-reading task were investigated. 10 subjects served in one of three groups receiving either continuous, periodic, or aperiodic noise. All subjects performed in both low noise (65 dBA) and high noise (85 dBA) conditions on 80 trials of both word reading and color naming. Median reaction times in the word-reading task were unaffected by either noise intensity or the time-varied aspects of the noise. However, median reaction times in the color-naming task were significantly elevated in the 85-dBA noise condition. Also, reaction times in the high aperiodic noise condition were significantly elevated relative to the continuous and periodic noise conditions. Results are discussed within the framework of arousal, filter, and information theories.

Adult↗
PubMed1976

Possibilities of improving the diagnosis of noise-induced hearing damage by means of directional audiometry, the dichotic speech discrimination test, and the EEG1.

Several audiometric tests were made of 85 noise workers exposed to an intensive impulse noise during pressing and punching. These tests aimed at finding out noise-induced central hearing damages (directional audiometry, dichotic speech discrimination test according to Feldmann and checking of the induction of the impedance jump). In addition, a clinical EEG was taken from each subject. Having obtained the necessary norms with series of tests in subjects with normal hearing abilities for their respective ages, the following results have been obtained: (1) directional hearing has hardly been affected by noise-induced hearing damage. It behaves like age changes in the group compared with it; (2) the dichotic speech discrimination test shows increasingly pathological values with progressive noise-induced hearing damage; this was already obvious in the age group 41-50. The impedance jump is less and less produced with progressive noise-induced hearing damage and finally disappears at a noise intensity of up to 110 dB. Because of these findings a progressive degeneration of the spiral ganglion and hearing nerve in noise-induced hearing damage is discussed as a cause of a deteriorated speech discrimination and the absence of the impedance jump. The EEG findings show changes in the alpha-rhythm in about 50% of the cases at an exposure time of 10 years onwards which may be possibly due to damage to the reticular formation, once increasing noise-induced hearing damage no longer exists.

Adult↗
PubMed1979

High-frequency audiometry and noise-induced hearing loss.

A group of noise-exposed male subjects with an audiogram that is characteristic for noise trauma were submitted to high-frequency audiometry (HFA) up to 20 000 HZ. The results were compared with those obtained in a group of normally hearing persons with no history of noise exposure. Conserved high frequency hearing was found. Very strict selection criteria were applied in both groups in order to avoid hereditary diseases and to ensure normal middle ear function. The findings are in good overall agreement with histological findings in noise-exposed animals and also with high-frequency studies in the older literature. Two illustrative case stories from patients with severe 4--6 kHz dips are reported, one with preserved high-frequency hearing in spite of a considerable acoustic trauma and one with extreme sensitivity towards noise and with no hearing at all in the high frequencies. It is concluded that 1) HFA cannot be used as an early indicator of the traumatic effect of high intensity noise; 2) presbycusis and noise damage may be additive elements in the older age groups (above 50 years); 3) persons with abnormal high-frequency hearing are possibly hypersensitive towards excessive noise and HFA might be useful in the routine audiological evaluation of workers before these are exposed to noise.

Adult↗
PubMed1992

Speech recognition in noise when wearing amplitude-sensitive ear-muffs.

Speech recognition in background noise when wearing amplitude sensitive (non-linear) ear muffs was studied in the laboratory in 15 young normal-hearing test subjects. Low-redundancy sentences were presented from a loudspeaker in a background noise level of 70 dB (A) and the speech-to-noise (S/N) ratio yielding 50% correctly recognized words was determined. Three background noise spectra were tested: white noise, low-pass filtered noise (-12 dB/octave) and high-pass filtered noise (12 dB/octave). Five listening conditions were used: no protectors, a pair of normal ear-muffs, a passive amplitude-sensitive ear-muff and two types of electronic amplitude-sensitive ear-muffs. An ANOVA shows that speech recognition is significantly influenced by type of hearing protector and by noise spectrum. The interaction between these factors was not statistically significant. In general, the test subjects obtained somewhat better speech recognition thresholds in noise when wearing electronic amplitude-sensitive ear muffs than without muffs, whereas the opposite was true for the passive amplitude-sensitive and the normal ear muffs.

Acoustic Stimulation↗
PubMed2002

Speech recognition threshold in slightly and fully modulated noise for hearing-impaired subjects.

A previously developed speech test with sentences in noise was modified in an attempt to increase its efficiency. Thus the original, slightly modulated (SM) noise was changed to be fully modulated (FUM), and the speech-to-noise ratio of each word was controlled to make all the words equally difficult. The new and the old version were compared in 41 hearing-impaired subjects. The learning effect was similar for both noises, but the variability was higher for the FUM noise. However, the efficiency of the speech test was slightly better for the FUM noise. Speech recognition in both types of noise was correlated with pure-tone thresholds at high frequencies, i.e. 2000 Hz and above, but not to tone thresholds at lower frequencies. Results in FUM noise and in SM noise were highly correlated, with a correlation coefficient of 0.86.

Aged↗
PubMed2002

Effects of high-frequency emphasis and compression time constants on speech intelligibility in noise.

The objectives of the study were to evaluate the effect of different settings with regard to speech intelligibility in noise both objectively and subjectively and thus determine a favoured setting of compression time parameters, pre-set program (high-frequency emphasis) or combination for each individual user in a prospective study. Another objective was to evaluate the relationship between patient characteristics (e.g. slope of hearing loss) and favoured settings. In total, 38 subjects divided over five audiological centres were fitted with the Philips Spaceline D71-40 BTE digital hearing aid. Subjects were asked to compare three predefined compression algorithms with different time constants, slow (indicated by the manufacturer as AVC), intermediate (NORMAL) and fast (SYLLABIC) over two 4-week periods using the intermediate setting in both comparisons and randomizing over the fast and slow conditions. A randomization determined whether a subject started with the comfort-oriented pre-set program (AUTO) or the speech intelligibility-oriented setting with high-frequency emphasis (SPIN). In a third 4-week period, the pre-sets AUTO and SPIN were compared using the setting of the compression time constants that gave the best results during the first two periods. Comparisons were made using a standard speech-in-noise test with three types of noise: continuous speaker noise, modulated ICRA-4 noise, and car noise. The patients were also asked to fill in a Dutch translation and adaptation of the APHAB questionnaire to indicate their impression of performance. The results indicate that no compression algorithm, pre-set or combination is favoured overall. The largest improvement in speech-in-noise scores was found with syllabic compression. The advantageous effect of high-frequency emphasis after optimization of compression timing is small. The APHAB showed that users tend to prefer the SPIN setting. We found no relationship between favoured compression or pre-set and the degree or steepness of the hearing loss User preference and best performance in noise do not always coincide. Acclimatization may play a role. It could be advisable to let a user listen to a subjectively less favoured condition for at least some time if an optimal setting for speech intelligibility in noise is preferred over comfort.

Acoustic Stimulation↗
PubMed2003

Evaluation of the noise reduction system in a commercial digital hearing aid.

We evaluated the effectiveness of a noise reduction system implemented in a commercial digital multichannel compression hearing aid. Eight experienced hearing aid wearers with moderate sensorineural hearing loss were fitted bilaterally according to the manufacturer's fitting guidelines. After a 3-month period of regular use of two programs, one with and one without the noise reduction system, speech recognition thresholds (SRTs) were measured in four types of background noise, including steady noise, and noises with spectral and/or temporal dips. SRTs were very similar with and without the noise reduction system; in both cases, SRTs were markedly lower than for unaided listening. SRTs were lower for the noises with dips than for the steady noise, especially for the aided conditions, indicating that amplification can help to 'listen in the dips'. Ratings of sound quality and listening comfort in the aided conditions were uniformly high and very similar with and without the noise reduction system.

Adult↗
PubMedDate not supplied

Combined effects of noise and gentamicin on hearing in the guinea pig.

The last ten years, the use of gentamicin has increased due to antibiotic resistance among bacterial pathogens. One of the side effects of gentamicin is its toxicity on hearing. Several authors had even pointed out synergistic effects of gentamicin and noise on hearing. It was therefore reasonable to think that the damaging effects of noise could be emphasized by a gentamicin treatment of the subjects. In order to test the applicability of the Leq8h for estimating the hazard of noise on animals treated with a non-ototoxic dose of gentamicin (40 mg/kg for 8 days), two experiments were carried out with guinea pigs. The animals were exposed to octave band noises centred at 8 kHz and treated with gentamicin either simultaneously or sequentially with regard to the noise exposure. Two noise exposures having different acoustic energy, respectively Leq8h = 85 dB and 98.8 dB SPL, were tested. The auditory function of the guinea pigs was tested by recording auditory-evoked potentials. The electrophysiological findings were completed by histological data. The gentamicin treatment tested in the current studies did not cause any auditory permanent threshold shift neither cochlear disruptions, although the treatment could be considered as approximately ten times the therapeutic dose used in human. The auditory deficit induced by the mixed exposures to noise and gentamicin did not worsen the noise effect alone in our experimental conditions. As a result, the European value recommended for noise exposure (Leq8h=85 dB) seems to be robust enough to protect gentamicin-treated workers.

Animals↗
PubMed1999

Measuring the noise attenuation of shotblasting helmets.

Air-fed blasting helmets are used in abrasive blasting operations to provide essential face, eye and respiratory protection. BS EN 271: 1995 (equivalent to the European Standard EN 271: 1997), the standard that deals with the construction of blasting helmets, addresses the above matters and also the problem of noise generated by the breathing air supply. However it has no requirements for manufacturers to measure or report the helmet's ability to attenuate the very high levels of noise generated by the blasting process. The aim of the project was to develop a test method to measure the noise attenuation of shotblasting helmets. The method developed is an objective measurement, using a head and torso simulator (HATS), which provides a suitable means for helmet manufacturers to report their product's ability to attenuate blasting noise. The results from this project showed that the HATS currently prescribed by BS EN 271: 1995 can be used for measuring the noise attenuation of helmets against typical shotblasting noise. Using such a HATS in the proposed test method will give attenuation values that correlate well with those measured using human subjects. Therefore the HATS already used by manufacturers to show compliance of their product with BS EN 271: 1995 could also be used to provide information on the helmet's noise attenuation. Results from this project also showed that the same HATS can be used, in place of human subjects, to measure the air supply noise according to the method defined in BS EN 271: 1995. BS EN 271: 1995 is due for revision in 2000. The results from this work should be used to influence future revisions of the standard so that requirements to measure and report noise attenuation of shotblasting helmets are considered, a major omission in the present standard.

Equipment Design↗
PubMed1999

[Environmental noise and satisfaction with area of residence].

In the German National Health Interview and Examination Survey, more than one third, i.e. 36.2% of persons interviewed on the matter of noise nuisance in their homes attributed to outdoor noise confirmed the occurrence of noise. Regarding this result only small and statistically insignificant differences have been assessed in East and West Germany. The frequency of affirmative answers given by German women, ages 20-39, was significantly higher as compared to men in the same ages bracket. Regarding the dominant noise effects in their home, 87% of persons affected mentioned traffic noise as a source. In the second place neighbour noise has been reported by 32%. Aircraft and railway noises percepted by 20%, are in the third and fourth place. Particularly severe indoor noise effects, i.e. persisting noise during the night, are accompanied with clearly increased discontent regarding the home and living area.

Adolescent↗
PubMed1999

Community noise policy in Denmark.

This paper summarizes an analysis of Danish policy on community noise during the last three decades seen in a public health perspective. Estimates made during this period of population exposures to noise from transport are presented, followed by data on population reactions to community noise. The analysis of the main elements of Danish community noise policy in the form of remedies, preventive actions and strategies leads to the conclusion that although exposures of the population to community noise have decreased during this period, the Danish policy was not consistent in the 1970s and 1980s. Administratively and politically, noise had low priority as an environment problem. The improvements in exposures from road traffic were probably mainly due to the legislation on physical planning, but also to lower speed limits and local traffic planning measures. During recent years important new steps have been taken, including the railway sector, but air traffic noise still represents a problem. Local authorities have, generally, been slow in giving priority to noise alleviating and preventive actions. Improved coordination at the central level is needed, and local action may raise the general awareness of the importance of our noise environment for health and well-being.

Denmark↗
PubMed2001

[Assessment of low frequency noise annoyance in steering premises according to subjective annoyance rating by workers. A pilot study].

The study covered 192 workers aged 26-62 years (mean 41 +/- 6), employed at workposts in the control rooms. A questionnaire was applied as a main tool of the study. The aim of the study was subjective annoyance rating of low frequency noise at workplaces on a 100-degree rating scale. Using the same scale, the study subjects rated annoyance of reference wide-band noise (60 +/- 2, 70 +/- 2, 75 +/- 2 and 80 +/- 2 dB(A)) and reference low frequency noise (65 +/- 2, 70 +/- 2, 75 +/- 2 and 80 +/- 2 dB(A)) reproduced by phones. Questionnaire inquires were preceded by the measurements of A-, C- and G-weighted equivalent continuous sound pressure levels (LA eq.T, LC eq,T i LG eq,T). Noise with prominent low frequency components (10-250 Hz) at A-weighted sound pressure level of 47.7-65.2 dB was assessed as more than somewhat annoying (more than 25 degrees on the 100-degree annoyance rating scale) by 70% of workers examined. No correlation between subjective annoyance rating of the noise at the workplaces and LA eq,T or LG eq,T was noted. Statistically significant correlation (r = 0.23) between subjective annoyance rating and LC eq,T was observed. The subjective rating of annoyance of the reproduced low frequency noise and wide-band noise differed significantly. Low frequency noise was rated as more annoying than wide-band noise at the same A-weighted sound pressure levels.

Adult↗
PubMed2002

Environmental impact of noise levels in and around opencast bauxite mine.

Until recently, noise pollution has not been paid adequate attention as air, water and land pollution. In order to assess (predict) the impact of bauxite mine noise on employees health and in and around bauxite mine environment, general noise sources and equipment noise were monitored. All these noise sources were compared with prescribed standard noise levels laid down by Central Pollution Control Board (CPCB). Data has also been compared with reference site, north block hill top which is barren and virgin plateau/top covered with grass only and free from human interference. Equipment noise levels were much higher than the other zone of the mine which does not have the corresponding standards. Rock breaker recorded the highest noise level with 73.1 +/- 14.2 to 89.5 +/- 10.1 dB (A) while from ripper dozer it was least with 61.0 +/- 17.3 to 76.2 +/- 6.2 dB (A). Meteorological parameters did not have much influence upon equipment noise up to 100 feet from the source.

Aluminum Oxide↗
PubMed1992

Effects of notch noise bandwidth on the auditory brainstem response to clicks.

The effects of notch width of notch masking noise on the auditory brainstem response (ABR) were investigated with ten normal-hearing subjects. Wave V latencies and amplitudes were measured to a click in quiet and in the presence of noise with notches centered around 1000 Hz and 4000 Hz. Notch width was either 0.5, 1.0, 1.5, 2.0, or 2.5 octaves. A 95 dB SPL broadband noise was necessary to mask a 65 dB nHL click at an effective level of 73 dB nHL. All ten subjects at both 1000 Hz and 4000 Hz yielded identifiable responses for the click in quiet and for the 2.5 octave and 2.0 octave conditions, and eight or nine subjects responded to the 1.5 octave notch noise. In contrast, no responses were observed to the 0.5 octave condition, and only three or four subjects responded to the 1.0 octave notch noise. These findings suggest that when ABRs are obtained to 65 dB nHL clicks in notch noise, the notch width should exceed 1.0 octave. Moreover, because of the relatively low amplitudes elicited with the 1.5 octave bandwidth, it appears preferable to select notches that are 2.0 to 2.5 octaves wide. Considering the wide bandwidth required, the high noise levels necessary to mask clicks, high ABR thresholds, and the difficulty setting the signal-to-noise ratio, it appears that tonepips are more promising than clicks in notch noise for assessing frequency specific ABRs.

Acoustic Stimulation↗
PubMed2003

Noise levels in the hospital environment in Ibadan.

Noise levels were measured in 3 hospitals in Ibadan; a teaching hospital with approximately 800 beds and 2 general hospitals with about 200 beds each. A type 2 digital integrating sound level meter was used to measure noise levels in selected sites. Children's clinics and wards in the teaching hospital recorded the highest noise levels, 68-73db(A) and 55-77db(A) respectively, compared to similar facilities for adults. High noise levels 74-89dB(A) were also recorded in the operating rooms. Noise levels above 80db (A) were recorded in service areas such as the boiler room, and laundry and generator rooms in the teaching hospital. Corresponding sites in the general hospitals were less noisy as such services are provided at a minimum in these hospitals. Sleep interference is known to occur at noise levels recorded in this study. Staff conversation makes a large contribution to noise levels in patient care areas. The use of hospital equipment in patient care also contributes to the noise levels especially in operating room. This can be reduced if attention is drawn to this as an important part of patient care. Noise levels in service areas need to be monitored closely and workers in those areas may need hearing protection and regular audiometric assessment.

Hospitals, General↗
PubMed2004

Influence of suction tube noise on hearing in pediatric patients who received ventilation tube insertion.

BACKGROUND: Myringotomy with ventilation tube insertion is the most frequently used surgical procedure performed on children to treat otitis media with effusion. The risk of acoustic trauma caused by the suctioning noise during the procedure has not been clearly understood. The objective of this study was to investigate whether the suctioning noise during ventilation tube placement procedure damaged children's hearing. METHODS: The study was conducted in a prospective manner. The ventilation tube placement procedures were performed on a series of 30 consecutive patients (60 ears). The electro-acoustic signals of the suctioning noises during the procedure were analyzed using a high quality digital tape recording system. The hearing threshold was measured using pure tone audiometry before and after the procedures. RESULTS: The peak intensity of the suctioning noise ranged from 4 kHz to 10 kHz in frequency. The mean intensities of the suctioning noise were 86.4 +/- 9.6 dB for serous effusion and 96.4 +/- 9.6 dB for mucoid effusion, respectively. No noise-induced sensori-neural hearing loss was observed in this cohort. CONCLUSIONS: Even though the peak intensity of the suctioning noise may reach a level of more than 90 dB, it is not likely that the suctioning noise during the ventilation tube placement procedure causes noise-induced sensori-neural hearing loss.

Adolescent↗
PubMed1991

Study of noise pollution in Jeddah hospitals.

The present study was conducted on a sample of 6 hospitals in Jeddah to investigate the status of noise pollution there, and as related to community background noise, operational activities, hospital size and operational concepts (public vs private). Generally, the levels of noise in the clinics, patient rooms, offices, waiting areas and corridors significantly exceed the recommended standard. The noise levels in the machinery rooms significantly exceed the levels in offices, waiting areas and corridors which, in turn, significantly exceed the levels in clinics and patient rooms. Background community noise has a little impact on indoor noise due to the construction characteristics of the hospitals' buildings. However, "operational noise" from machinery and from the move of public (patients, attendants and employees) significantly contribute to indoor noise. Proper site location, city planning, traffic engineering, building construction, equipment selection, construction and equipment maintenance, and system management have been recommended for the abatement of hospital noise pollution.

Health Facility Environment↗
PubMed1987

[Risk of noise-induced hearing loss caused by radio communication? Audiologic findings in helicopter crews and pilots of propeller airplanes].

The affects of noise on the human inner ear have been well known for a long time, and measures to prevent occupational noise-induced hearing loss show a clear reduction in the statistics of morbidity. Nevertheless, there are working environments in which the use of ear protection seems to be inapplicable, because communication by speech is indispensable, for example in the cockpit of aircraft. Noise exposure measurements were performed on pilots of helicopters and propeller-machines of the German Federal Navy during realistic flight situations. The ambient noise levels during regular flight service were maintained at levels between 89 dB and 120 dB. Sound protection by flight-helmets and headphones is not only neutralised while using radio and intercom, but the noise during radio-communication is even louder than the noise of the engines. The use of ear protection to avoid excessive noise exposure is only of limited effectiveness. While pilots with normal hearing show only little impairment of speech intelligibility, those with noise-induced hearing loss show substantial impairment that varies in proportion to their hearing loss. Communication abilities may be drastically reduced which may compromise the reliability of radio-communication. The problem may be possibly solved in future by an electronic compensation system for noise.

Aircraft↗