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PubMed1992

[Combined use of glucose and rest period between noise exposure to reduce noise--induced hearing loss].

This paper reports the way which protects hearing from harmful effects of noise. 67 guinea pigs were divided into four groups, 8-9 guinea pigs in each group. The total time of noise exposure at 125 dB SPL white noise in each group was one hour. The control was exposed continuously for 1 hour. Group I was exposed to noise for 30 minutes after intraperitoneal injection of glucose at 2 mg/g body wt., then rest for 30 minutes and exposed for 30 minutes again. Group II was exposed continuously to noise for 1 hour after intraperitoneal injection of glucose at 2 mg and 4 mg/g body wt. Group III was exposed to noise for 30 minutes, rested for 30 minutes and exposed for 30 minutes again without glucose injection. The auditory brain stem response (ABR) was measured before, immediately, 3 days, and 7 days after noise exposure. The effect on hearing conservation was evaluated according to ABR threshold. We observed that the auditory threshold in group I was significantly lower than that of the control in the given time after noise exposure (P less than 0.05), but not so in group II and III. Combined use of glucose and rest period between noise exposure was able to decrease the threshold shift by 15 dB and 10 dB immediately and 7 days after noise exposure respectively.

Animals↗
PubMed1991

Auditory brainstem response to clicks in quiet, notch noise, and highpass noise.

Auditory brainstem responses to clicks in quiet, notch noise, and highpass noise were recorded from 10 normal-hearing adults. Contrary to some reports, the latency of wave V increased as the center frequency of the notch decreased. Response identifiability and wave V amplitudes were similar for the notch and highpass noises. Thus, the additional frequencies below the notch did not contribute sufficiently to the response to alter identifiability or amplitude. Notch noise, as compared to the highpass noise, is advantageous because of the increased frequency-specificity provided by the low-frequency masking noise. Presenting clicks in highpass or notch noise centered at 500 Hz is of limited value for assessing auditory sensitivity. This is because the range of testable hearing levels is restricted by (1) a high normal ABR threshold (approximately 65 dB nHL) and (2) the high noise levels required to mask the click. This limited dynamic range for assessing hearing loss is a major limitation of click in noise testing, particularly for 500 Hz. Generating a two-point audiogram by presenting clicks in noise with notches centered around 1000 Hz and 4000 Hz may prove promising for assessing auditory sensitivity.

Acoustic Stimulation↗
PubMed1997

Discrimination of rippled-spectrum noise from flat-spectrum noise by chinchillas: evidence for a spectral dominance region.

Iterated rippled noise having infinite iterations is generated when a flat-spectrum wideband noise is delayed T ms and the delayed version is added to the undelayed noise through positive feedback. The resulting signal has a rippled spectrum, and the perceived pitch of this iterated rippled noise by human listeners corresponds to a frequency of 1/T. We have previously demonstrated that chinchillas can discriminate the rippled-spectrum noise from the flat-spectrum noise. In the present study, chinchillas discriminated a bandpass filtered rippled-spectrum noise from a bandpass flat-spectrum noise in a psychophysical task. The passbands were set to be one octave wide. Psychometric functions were obtained for 5 chinchillas and performance was measured as d'. The best behavioral performance was obtained when the center frequency of the bandpass filter generally corresponded to the 3rd 5th harmonic peak of the rippled noise (i.e., at 3/T to 5/T), but the precise location of the dominant region varied with the delay of the rippled noise such that the dominance region tended to shift to lower harmonics as 1/T increased. These results indicate that not all spectral regions are weighted equally in the discrimination task. The spectral dominance region found in chinchillas is similar to that described for human pitch perception.

Acoustic Stimulation↗
PubMed2001

Effects of colored noise on stochastic resonance in a bistable system subject to multiplicative and additive noise.

The effects of colored noise on stochastic resonance (SR) in a bistable system driven by multiplicative colored noise and additive white noise and a periodic signal are studied by using the unified colored noise approximation and the theory of signal-to-noise ratio (SNR) in the adiabatic limit. In the case of no correlations between noises, there is an optimal noise intensities ratio R at which SNR is a maximum that identifies the characteristics of the SR when the correlation time tau of the multiplicative colored noise is small. However, when tau is increased, a second optimal value of R appears, and two peaks appear in the SNR simultaneously. In the case of correlations between noises, the SNR is not only dependent on the correlation time tau, but also on the intensity of correlations between noises. Moreover, the double peak phenomenon can also appear as tau is increased in certain situations.

Journal Article↗
PubMed2005

Industrial wideband noise reduction for hearing aids using a headset with adaptive-feedback active noise cancellation.

High-intensity noises are a health hazard for industrial workers, and hearing protection is necessary to prevent hearing loss. Passive methods, such as ear muffs, are ineffective against low-frequency noise. Moreover, many hearing-impaired workers must wear hearing aids to enable communication at their workplace, and such aids can amplify ambient noise. To overcome this problem, the present study developed a headset equipped with a digital signal processing system to implement adaptive-feedback active noise cancellation (AFANC) to reduce low-frequency noise. The proposed AFANC headset was effective against wideband industrial noise, with a maximum noise spectrum power reduction of 30 dB. Furthermore, when used with a hearing aid, it improved the speech signal-to-noise ratio by up to 14 dB. These results suggest that a headset with AFANC would be useful for hearing protection in workplaces with high levels of low-frequency industrial noise, especially for hearing-impaired workers.

Ear Protective Devices↗
PubMed1991

Delayed temporary threshold shift induced by impulse noises (weapon noises) in men.

Most of the available information on the effects of impulse noise on hearing is derived from temporary threshold shift (TTS2) measurements performed 2 min after a single exposure to small-weapon noises. TTS is known to recover as a linear function of the logarithm of time when it is induced by a continuous noise of moderate intensity. Following the exposure to impulse noise, several investigators have reported individual exceptions to the log-time relation, e.g. increases in TTS during the first hour of recovery. These authors observed a 'rebound recovery function' for most of the exposed men, and they conclude that this phenomenon '... has implications for the use of TTS in the construction of damage risk criteria for hazardous noise exposure ..., a single measure, such as the widely used TTS2 may not be an adequate index of the magnitude of the TTS'. In order to thoroughly investigate in man the existence of 'delayed' TTS following the exposure to actual weapon noises, the 'French Committee on Weapon Noises' carried out the following study. Three groups of soldiers (28 subjects) wearing no hearing protection were exposed in the free field over 2 days to impulse noises produced by a rifle. Békésy audiograms were obtained from each subject just before the exposure, and at 5 min, 1 h and 4 h after exposure. All audiometric tests were carried out even when no TTS was observable in the first postexposure audiogram. A significant number of subjects showed a 'delayed TTS' and/or 'rebound recovery'. The maximum TTS was observed at 1 h after exposure, but the observation of a delayed recovery and a rebound recovery indicate that audiometric tests should be performed in all cases at least up to 4 h after the exposure. More detailed work is necessary to establish what changes may be necessary in the present damage risk criteria for impulse noises of a very high level.

Adult↗
PubMed1993

[Perception of traffic noise emission in Basel City canton in comparison to actually measured noise levels].

The objective of this study was to assess to what extent the subjective annoyance is influenced by the actually measured or calculated street traffic noise and by sociodemographic factors. In the study on air pollution and health in Basle a representative sample of 1033 families with children up to five years were asked how they perceived street traffic noise. The extent of annoyance was assessed with a scale from 0 (no annoyance) to 10 (unbearably annoyed). The actual noise levels were taken from the official noise-register. Nearly 30% of the families were exposed to > 65 dB(A) in daytime. Immigrant families as well as participants with low education more frequently lived in streets with higher noise levels than Swiss families or participants with higher education. 16.4% considered themselves heavily annoyed by traffic noise (scale 8-10). The proportion of heavily annoyed participants was positively correlated with the actual noise levels, the slope was steepest at a noise level between 60-65 dB(A). By means of a multiple regression it could be shown that, adjusting for education level and city district, the actual noise level was the best predictor of subjective annoyance.

Adolescent↗
PubMed1997

[Noise in intensive care units. Noise reduction by modification of gas humidification].

Today, noise pollution is an evident and ubiquitous problem even in intensive care units. Noise can disturb the physiological and psychological balance in patients and staff. Especially intubated patients and those breathing spontaneously through a T-piece are exposed to the noise emitted by the nebuliser used to humidity the respiratory gas. This may make patients feel uncomfortable. To reduce noise pollution in the ICU a modified T-piece has been developed and investigated. In order to heat and humidity the respiratory gas a Conchaterm III unit (Kendall company) and a thermo flow cylinder (De Vilbiss company) is necessary. While respiratory gas is flowing, water is sucked out of the heated thermoflow cylinder and nebulised according to the Venturi-Bernoulli principle. To adjust the oxygen concentration of the respiratory gas a plastic ring must be turned to either close (98% oxygen) or open a valve allowing room air to mix (40% oxygen). Noise pollution of the unit varies with admixture of room air. With a new device--a special oxygen-air mixing chamber--the oxygen concentration of the respiratory gas can be adjusted outside the thermoflow cylinder, hardly producing any noise pollution. Therefore the principle of nebulisation could be changed to humidification. A thermoflow cylinder without the nebulisation unit allows the respiratory gas to flow through the thermoflow cylinder over heated and evaporating water, hardly causing any noise pollution. In both types of T-pieces the temperature of the respiratory gas is controlled and corrected by the Conchaterm unit. As the result of these modifications, noise pollution has been reduced from 70 dB(A) to 55 dB(A). In the modified T-piece, the quality of humidification has been evaluated with a fresh gas flow of 22 l/min and at a gas temperature of 37 degrees C, not only collecting condensed water but also lost water. The modified T-piece allows a physiological humidification of the respiratory gas. The modified T-piece is a simple and efficacious substitute. Patients and staff are protected from adverse noise effects and patient well-being might be improved.

Humans↗
PubMed1993

Road traffic noise, noise sensitivity and psychological disorder.

The relationship between traffic noise exposure and psychological morbidity was assessed using the population-based Caerphilly Collaborative Survey of 2398 men from Caerphilly, South Wales. The findings showed that traffic noise exposure levels were strongly associated with annoyance to noise. Noise-sensitive men were more likely to be highly annoyed by noise exposure than less noise-sensitive men. There was no direct association between noise exposure level and psychological morbidity but there were provocative interactions with noise sensitivity. The role of noise sensitivity is discussed as an indicator of vulnerability to environmental stressors and a measure of negative affectivity and over-reporting.

Cohort Studies↗
PubMed2004

Comparison of speech perception in background noise with acceptance of background noise in aided and unaided conditions.

Background noise is a significant factor influencing hearing-aid satisfaction and is a major reason for rejection of hearing aids. Attempts have been made by previous researchers to relate the use of hearing aids to speech perception in noise (SPIN), with an expectation of improved speech perception followed by an increased acceptance of hearing aids. Unfortunately, SPIN was not related to hearing-aid use or satisfaction. A new measure of listener reaction to background noise has been proposed. The acceptable noise level (ANL), expressed in decibels, is defined as a difference between the most comfortable listening level for speech and the highest background noise level that is acceptable when listening to and following a story. The ANL measure assumes that speech understanding in noise may not be as important as is the willingness to listen in the presence of noise. It has been established that people who accept background noise have smaller ANLs and tend to be "good" users of hearing aids. Conversely, people who cannot accept background noise have larger ANLs and may only use hearing aids occasionally or reject them altogether. Because this is a new measure, it was important to determine the reliability of the ANL over time with and without hearing aids, to determine the effect of acclimatization to hearing aids, and to compare the ANL to well-established measures such as speech perception scores collected with the SPIN test. Results from 50 listeners indicate that for both good and occasional hearing aid users, the ANL is comparable in reliability to the SPIN test and that both measures do not change with acclimatization. The ANLs and SPIN scores are unrelated. Although the SPIN scores improve with amplification, the ANLs are unaffected by amplification, suggesting that the ANL is inherent to an individual and can be established prior to hearing aid fitting as a possible predictor of hearing-aid use.

Adaptation, Physiological↗
PubMed1989

The effects of "noise suppression" hearing aids on consonant recognition in speech-babble and low-frequency noise.

We evaluated the performance of experienced hearing-aid users wearing seven different commercially available "noise-suppression" hearing aids. Two hearing aids, the Audiotone A-54 and the Telex 363C, used amplitude compression. The others, two versions of a Maico hearing aid SP147, a Richards ASE-B, a Rion HB-69AS, and a Siemens 283ASP, are designed to attenuate specific frequency regions in the presence of noise. Sixteen subjects listened to 13 consonants in the form (i)-consonant-(i) with six replications per consonant (78 items). Performance was measured with the compression or noise-suppression circuit on and off in the presence of speech-babble noise and in continuous low-frequency noise. Measurements were also obtained with the suppression circuit "off" but without any background noise. The results suggested that only a few subjects benefitted from the noise-suppression circuits, and in several cases performance in noise was poorer with the noise suppression circuit than without it. An information-transfer analysis of the errors indicated that enhanced or decreased performance was generally a result of changes across all phonetic features, not specific ones.

Adult↗
PubMed2005

Annoyance with aircraft noise in local recreational areas and the recreationists' noise situation at home.

Few socioacoustic studies have examined the effect of noise on outdoor recreationists. Most studies concentrate on one setting of the everyday life of a noise-exposed population, which mainly has been the residential setting. This article relates annoyance with aircraft noise in outdoor recreational areas to the recreationists' noise situation at home. In conjunction with the relocation of the main airport of Norway in 1998, field studies were conducted before and after the change in one area near the old airport (1930 survey respondents), and one area near the new airport (1001 survey respondents). Multivariate linear regression analyses of the relationship between annoyance and aircraft noise exposure (LAeq for the aircraft events) in the recreational areas were conducted, controlled for noise annoyance at home, or aircraft noise exposure at home, the situation (before/ after the change), context- and demographic variables. People more highly annoyed at home tended to be more annoyed than others while in the recreational areas. A significant effect of aircraft noise exposure at home on annoyance in the recreational setting was not found. More research is warranted regarding the relationship between noise exposure at home and outdoor recreational demands.

Aircraft↗
PubMed1983

Growth of forward masking for sinusoidal and noise maskers as a function of signal delay; implications for suppression in noise.

The first two experiments were designed to determine whether mutual suppression in broadband noise increases in strength with increasing overall level. In experiment I masking functions (signal threshold versus masker level) were measured in forward masking as a function of the delay time of a 10-ms signal, both for a broadband noise masker (low-pass filtered at 8 kHz) and for sinusoidal maskers at 1, 2 and 4 kHz. In the latter case the signal frequency equaled the masker frequency. For short signal delays the masking functions were steeper for the sinusoidal masker than for the noise masker. At longer delays the slopes for both masker types decreased and the slopes for the two masker types became more nearly equal. In experiment II we investigated the effect of gating a low-level noise cue with the sinusoidal masker. At the longer signal delays the masking functions had equal slopes for the broadband noise masker and the sinusoidal masker with cue. At short signal delays the masking functions for sinusoidal maskers may be "artificially" steepened, since the subject lacks an effective cue to distinguish the signal from the masker. The equal slopes at longer delays indicate that mutual suppression of the components within a broadband noise does not increase in strength with increasing overall level. In experiment III we attempted to estimate the magnitude of mutual suppression in a broadband noise by comparing masking functions for a broadband noise and for a noise whose bandwidth was 20% of the center frequency. The suppression was estimated to be about 2 dB at 4 kHz and 8 dB at 2 kHz. A simple mathematical expression, suggested by Jesteadt et al. [J. Acoust. Soc. Am. 71, 950-962 (1982)], was found to give an accurate description of the amount of masking produced by the broadband masker as a function of masker level and signal delay.

Auditory Threshold↗
PubMedDate not supplied

Strength of noise effects on memory as a function of noise source and age.

The objectives in this paper were to analyse noise effects on episodic and semantic memory performance in different age groups, and to see whether age interacted with noise in their effects on memory. Data were taken from three separate previous experiments, that were performed with the same design, procedure and dependent measures with participants from four age groups (13-14, 18-20, 35-45 and 55-65 years). Participants were randomly assigned to one of three conditions: (a) meaningful irrelevant speech, (b) road traffic noise, and (c) quiet. The results showed effects of both noise sources on a majority of the dependent measures, both when taken alone and aggregated according to the nature of the material to be memorised. However, the noise effects for episodic memory tasks were stronger than for semantic memory tasks. Further, in the reading comprehension task, cued recall and recognition were more impaired by meaningful irrelevant speech than by road traffic noise. Contrary to predictions, there was no interaction between noise and age group, indicating that the obtained noise effects were not related to the capacity to perform the task. The results from the three experiments taken together throw more light on the relative effects of road traffic noise and meaningful irrelevant speech on memory performance in different age groups.

Adolescent↗
PubMed2003

Polish version of standardized noise reaction questions for community noise surveys.

OBJECTIVES: This article presents the Polish version of two standardized noise reaction questions for community noise surveys. An internationally comparable noise reaction measure for social surveys was published by Fields et al. as a result of work performed by the Community Response to Noise Team of the International Commission on the Biological Effects of Noise. This measure consists of two recommended noise reaction questions: a 5-point verbal scale question and a 0-10-point numeric scale question. METHODS: The Polish words for a 5-point noise annoyance verbal scale were selected by respondents from a group of 21 potential adverbs following the method described by Fields et al. The same standardized empirical study protocol was used to select annoyance scale words (a 5-point verbal scale question) for the nine different languages. RESULTS: The following words for a 5-point noise annoyance scale were obtained: not at all, a little, rather, substantially, extremely annoying. CONCLUSIONS: The Polish version of the scale described in this paper has international counterparts. It means that our data expand the world database on human reactions to noise in different communities and become more comparable with the data from other countries.

Auditory Perception↗