Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “NOISE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed1998

Beneficial effects of notched noise on intensity discrimination in the region of the "severe departure".

Intensity discrimination for a 6-kHz sinusoidal pedestal was measured in quiet and in the presence of a noise background. In the first experiment, the level of a 30-ms pedestal was fixed at 45 dB SPL and presented in the temporal and spectral center of a 110-ms notched noise. For a noise spectrum level of between 0 and 15 dB the noise produced a substantial reduction in the Weber fraction, i.e., an improvement in detectability, compared to the condition without the noise. The second experiment showed that, unlike the situation with notched noise, narrow-noise produced no performance improvement, suggesting that the effect is dependent on noise frequency components outside the critical band of the pedestal. The third experiment showed that the improvement also occurred for a 6-ms pedestal presented in a 10-ms gap between two bursts of notched noise. The experiment rules out an explanation for the effect of the noise in terms of suppression on the basilar membrane. Finally, the effect was shown to decrease as the gap between the noise bursts was increased, in a manner at least broadly consistent with the decay of the temporal excitation pattern. It is suggested that the improvement in intensity discrimination in notched noise is due to an across-frequency comparison mechanism similar to "profile analysis," perhaps operating on a temporally smoothed central representation of the stimulus.

Auditory Perception↗
PubMed1983

Auditory nerve representation of vowels in background noise.

Responses of auditory nerve fibers to steady-state vowels presented alone and in the presence of background noise were obtained from anesthetized cats. Representation of vowels based on average discharge rate and representation based primarily on phase-locked properties of responses are considered. Profiles of average discharge rate versus characteristic frequency (CF) ("rate-place" representation) can show peaks of discharge rate in the vicinity of formant frequencies when vowels are presented alone. These profiles change drastically in the presence of background noise, however. At moderate vowel and noise levels and signal/noise ratios of +9 dB, there are not peaks of rate near the second and third formant frequencies. In fact, because of two-tone suppression, rate to vowels plus noise is less than rate to noise alone for fibers with CFs above the first formant. Rate profiles measured over 5-ms intervals near stimulus onset show clear formant-related peaks at higher sound levels than do profiles measured over intervals later in the stimulus (i.e., in the steady state). However, in background noise, rate profiles at onset are similar to those in the steady state. Specifically, for fibers with CFs above the first formant, response rates to the noise are suppressed by the addition of the vowel at both vowel onset and steady state. When rate profiles are plotted for low spontaneous rate fibers, formant-related peaks appear at stimulus levels higher than those at which peaks disappear for high spontaneous fibers. In the presence of background noise, however, the low spontaneous fibers do not preserve formant peaks better than do the high spontaneous fibers. In fact, the suppression of noise-evoked rate mentioned above is greater for the low spontaneous fibers than for high. Representations that reflect phase-locked properties as well as discharge rate ("temporal-place" representations) are much less affected by background noise. We have used synchronized discharge rate averaged over fibers with CFs near (+/- 0.25 octave) a stimulus component as a measure of the population temporal response to that component. Plots of this average localized synchronized rate (ALSR) versus frequency show clear first and second formant peaks at all vowel and noise levels used. Except at the highest level (vowel at 85 dB sound pressure level (SPL), signal/noise = +9 dB), there is also a clear third formant peak. At signal-to-noise ratios where there are no second formant peaks in rate profiles, human observers are able to discriminate second formant shifts of less than 112 Hz. ALSR plots show clear second formant peaks at these signal/noise ratios.

Animals↗
PubMed1998

Noise-induced tuning curve changes in mechanoreceptors.

Fibers from the tibial nerve of rat were isolated and spike activity recorded using monopolar hook electrodes. The receptive field (RF) of each recorded unit on the glabrous skin of the foot was mechanically stimulated with waveforms comprised of various frequency sine waves in addition to increasing levels of white noise. Single-unit responses were recorded for both rapidly adapting (RA) and slowly adapting (SA) units. Signal-to-noise ratio (SNR) of the output was quantified by the correlation coefficient (C1) between the input sine wave and the nerve responses. The addition of noise enhanced signal transmission in both RA and SA fibers. With increasing noise, the initially inverted "V"-shaped, zero-noise tuning curves for RA fibers broadened and eventually inverted. There was a large expansion of the frequencies that the RA receptor responded to with increasing noise input. On the other hand, the typical shape of the SA fiber tuning curves remained invariant, at all noise levels tested. C1 values continued to increase with larger noise input for higher frequencies, but did not do so at the lowest frequencies. For both RA and SA fibers the responses with added noise tended to be rate modulated at the low-frequency end, and followed nonlinear stochastic resonance (SR) properties at the higher frequencies. The changes in the tuning properties due to noise found here, as well as preliminary psychophysics data, imply that external noise is relevant for sensing small periodic signals in the environment. All current models of sensory perception assume that the tuning properties of receptors determined in the absence of noise are preserved during everyday tasks. Our results indicate that this is not true in a noisy environment.

Adaptation, Physiological↗
PubMed1997

[Pulse phenomenon of continuous white noise with interrupted pure tone].

The researches of masking made it clear that there is a bandpass like a filter in the auditory system. This is called the auditory filter and its central frequency is thought to be the frequency of an acoustic signal. If there exist this kind of filter, the authors expected that the noise image which is perceived when pure tone and noise simultaneously presented is different from the one which is perceived when noise is presented independently. The authors chose an interrupted pure tone as an acoustic signal and continuous white noise as noise, and experimented to investigate the pure tone effect on perception of white noise. As a result, two stimulus tones induced three sound images, which are sound images of continuous noise, a pure tone and pulsed noise. The sound image which listeners did not expect to hear was the pulsed noise image. This phenomenon was thought to be an auditory induction; the inducer is the sound image of the white noise presented with the silent part of pure tone of interrupted pure tone and the inducee is that of the white noise presented with pure tone part of interrupted pure tone. This pulse phenomenon suggests that pure tone change the loudness of white noise. This finding is interesting for researches of auditory mechanism and for the field of hygienics with protecting the auditory system and improving hearing under the noisy environment.

Acoustic Stimulation↗
PubMed1998

Identification and modification of environmental noise in an ICU setting.

STUDY OBJECTIVES: Noise levels in the hospital setting are exceedingly high, especially in the ICU environment. We set out to determine what caused the noises producing sound peaks > or = 80 A-weighted decibels (dBA) in our ICU settings, and attempted to reduce the number of sound peaks > or = 80 dBA through a behavior modification program. DESIGN: The study was divided into two separate phases: noise identification and a trial of behavior modification. During the noise identification phase we simultaneously recorded sound peaks and the loudest noise heard subjectively by one observer in the medical ICU (MICU) and the respiratory ICU (RICU). During the behavior modification phase of the study we implemented a behavior modification program, geared toward noise reduction, in all of the MICU staff. Sound levels were monitored before and at the end of the behavior modification trial. SETTING: The MICU and RICU of a 720-bed teaching hospital in Providence, RI. PARTICIPANTS: All ICU staff during the study period. INTERVENTIONS: Once the noises that were determined to be amenable to behavior modification were identified, a behavior modification program was conducted during a 3-week period in our MICU. Baseline and post-behavior modification noise recordings were compared in 6-h intervals after sites were matched by number of patients in a room and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores. MEASUREMENTS AND RESULTS: We identified several causes of sound peaks > or = 80 dBA amenable to behavior modification; television and talking accounted for 49%. We also significantly reduced the 24-h mean peak noise level (p=0.0001), as well as the mean peak noise level (p=0.0001) and the number of sound peaks > or = 80 dBA (p=0.0001) in all 6-h blocks except for the 12 AM to 6 AM period. CONCLUSIONS: We conclude that many of the noises causing sound peaks > or =80 dBA are amenable to behavior modification and that it is possible to reduce the noise levels in an ICU setting significantly through a program of behavior modification.

APACHE↗
PubMed1992

Influence of noise on heart rate and quantity of work in mental work.

In the present study, we investigated the correlation between the physiological function, heart rate (HR) and the quantity of work performed when A-weighted sound pressure level of factory noise or construction noise was varied during the mental operations of calculation and erosion. Furthermore, we looked for differences in the effects of sound noise and music on the quantity of work performed. The A-weighted sound pressure level was set at four levels of background noise, i.e. 60, 70 and 80 dB (A). The music sound level was set at 70 dB (A). The subjects were exposed to factory noise, construction noise and music during their mental work. A balanced factorial experiment was conducted with a total of 16 combinations of types of mental work (two levels of calculation and erosion), sound noise (two levels of factory and construction sound noise), and A-weighted sound pressure levels (four levels). The order of the experimental procedures was determined at random. The following conclusions were made from the findings of the study. 1) HR elevation occurred due to exposure to sound noise, and further increase in HR resulted from an increase in the A-weighted sound pressure level. This result can be attributed to the action of sound noise as a stressor, which excites sympathetic nerves, leading to an elevation of HR. 2) The quantity of work performed decreased with an increase in the A-weighted sound pressure level. 3) When the subjects were exposed to music with an A-weighted sound pressure level of 70 dB (A) instead of sound noise of the same level, almost no elevation of HR was observed. However, the quantity of work completed when exposed to music was less than that performed when exposed to sound noise of the same A-weighted sound pressure level.

Heart Rate↗
PubMed2002

Cochlear delivery of fibroblast growth factor 1 and its effects on apoptosis and cell cycling in noise-exposed guinea pig ears.

OBJECTIVES: Acidic fibroblast growth factor 1 (FGF-1) is a mitogen and antiapoptotic factor synthesized by cochlear neurons and transported to the organ of Corti. The objectives of this investigation were threefold: (1) to develop an animal model to study the cochlear effects of intratympanic delivery of FGF-1; (2) to determine the distribution, in the mature mammalian cochlea, of FGF-1 and the receptor, FGFR3, to which it binds with high affinity; and (3) to examine the effect of exogenous FGF-1 on cochlear apoptotic and cell-cycling markers in noise and non-noise-exposed guinea pigs ears. METHODS: Fifteen adult Hartley guinea pigs were divided into three groups. Group 1 animals (n = 5) underwent direct placement of FGF-1 in phosphate buffered saline (PBS) (20 pg/mL) soaked Gelfoam pledgets to the right round window membrane. Phosphate buffered saline-soaked Gelfoam pledgets were placed on the left round window membrane as a control. In group 2 animals (n = 5), surgical placement of either FGF-1 or PBS was followed by exposure to 120 dB of white noise for 2 hours. Group 3 animals (n = 5) were subjected to identical noise conditions prior to undergoing round window application of either FGF-1 or PBS. All groups were allowed to recover in a noise-controlled environment for 12 hours following surgery. Anti-FGF-1-stained Western blots and optical densitometry analyses were used to quantitate passage of FGF-1 into cochlear perilymph. Standard in situ immunohistochemical techniques were used to stain each cochlea for FGF-1 and FGFR3, apoptotic markers p53 and p21, Bcl-2, and the cell-cycling marker proliferating cell nuclear antigen (PCNA). Tissue sections were subjected to the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling technique (TUNEL) for apoptosis. RESULTS: Western blot and optical densitometry analyses of cochlear perilymph showed increased concentrations of FGF-1 in 10 of 14 experimental cochleas. Cochlear perilymph FGF-1 was consistently bound to heparan sulphate proteoglycan (HSPG). Immunoreactivity of both FGF-1 and FGFR3 was observed in spiral ganglion neurons, inner and outer hair cells, pillar cells, and Dieter and Hensen's cells. Specific FGF-1 immunostaining to the distal portion of the pars pectinata of the basilar membrane was noted in noise-exposed animals only. Bcl-2 and PCNA immunostaining was not detected in any group. There was no significant nuclear immunoreactivity to proapoptotic markers, p53 and p21, in any group. Semiquantitative analysis of TUNEL staining in block sections of all cochleas demonstrated a 340% increase in nuclear immunoreactivity of noise-exposed outer hair cells and organ of Corti cells. There was no difference between FGF-1 treated and control ears subjected to TUNEL staining. CONCLUSIONS: Exogenous FGF-1 crosses the round window membrane and is bound to HSPG in cochlear perilymph. The specific immunoreactivity of the pars pectinata to FGF-1 may represent a unique reservoir for cochlear FGF-1 in noise-exposed ears of the guinea pig. Noise induces apoptosis of organ of Corti cells as demonstrated with the TUNEL technique. PCNA, Bcl-2, p53, and p21 in noise-exposed and non-noise-exposed guinea pig cochleas are not affected by exogenous FGF-1. Noise-induced hair cell apoptosis appears to be independent of the p53 pathway. Lack of immunoreactivity to Bcl-2 supports the concept that the apoptotic mechanism is likely to involve C-Jun-N-terminal kinase- or caspase-dependent pathways. Exogenous FGF-1 does not alter apoptosis or cell cycling in the mature guinea pig cochlea within 12 hours of acute acoustic trauma.

Animals↗
PubMed1996

Use of speech-modulated noise adds strong "bottom-up" cues for phonemic restoration.

When deleted segments of speech are replaced by extraneous sounds rather than silence, the missing speech fragments may be perceptually restored and intelligibility improved. This phonemic restoration (PhR) effect has been used to measure various aspects of speech processing, with deleted portions of speech typically being replaced by stochastic noise. However, several recent studies of PhR have used speech-modulated noise, which may provide amplitude-envelope cues concerning the replaced speech. The present study compared the effects upon intelligibility of replacing regularly spaced portions of speech with stochastic (white) noise versus speech-modulated noise. In Experiment 1, filling periodic gaps in sentences with noise modulated by the amplitude envelope of the deleted speech fragments produced twice the intelligibility increase obtained with interpolated stochastic noise. Moreover, when lists of isolated monosyllables were interrupted in Experiment 2, interpolation of speech-modulated noise increased intelligibility whereas stochastic noise reduced intelligibility. The augmentation of PhR produced by modulated noise appeared without practice, suggesting that speech processing normally involves not only a narrowband analysis of spectral information but also a wideband integration of amplitude levels across critical bands. This is of considerable theoretical interest, but it also suggests that since PhRs produced by speech-modulated noise utilize potent bottom-up cues provided by the noise, they differ from the PhRs produced by extraneous sounds, such as coughs and stochastic noise.

Attention↗
PubMedDate not supplied

Noise annoyance in Canada.

The present paper provides the results from two nation-wide telephone surveys conducted in Canada on a representative sample of 5,232 individuals, 15 years of age and older. The goals of this study were to gauge Canadians' annoyance towards environmental noise, identify the source of noise that is viewed as most annoying and quantify annoyance toward this principal noise source according to internationally accepted specifications. The first survey revealed that nearly 8% of Canadians in this age group were either very or extremely bothered, disturbed or annoyed by noise in general and traffic noise was identified as being the most annoying source. A follow-up survey was conducted to further assess Canadians' annoyance towards traffic noise using both a five-item verbal scale and a ten-point numerical scale. It was shown that 6.7% of respondents indicated they were either very or extremely annoyed by traffic noise on the verbal scale. On the numerical scale, where 10 was equivalent to "extremely annoyed" and 0 was equivalent to "not at all annoyed", 5.0% and 9.1% of respondents rated traffic noise as 8 and above and 7 and above, respectively. The national margin of error for these findings is plus or minus 1.9 percentage points, 19 times out of 20. The results are consistent with an approximate value of 7% for the percentage of Canadians, in the age group studied, highly annoyed by road traffic noise (i.e. about 1.8 million people). We found that age, education level and community size had a statistically significant association with noise annoyance ratings in general and annoyance specifically attributed to traffic noise. The use of the International Organization for Standardization/Technical Specification (ISO/TS)-15666 questions for assessing noise annoyance makes it possible to compare our results to other national surveys that have used the same questions.

Adolescent↗
PubMedDate not supplied

Prevention of adverse effects of noise on children.

This article presents findings from a European project co-ordinated by the National Institute of Public Health, Denmark. The project "Children and noise--prevention of adverse effects" was partly financed by the European Commission Programme on Pollution-related Diseases and included partners or consultants from six European Union Member States: Denmark, Germany, Italy, the Netherlands, Sweden and the United Kingdom. The project used a definition of noise based on children's special development and provides examples of good practice on how to prevent the harmful effects of noise in children's daily settings. The settings analysed were day-care centres, primary schools and discotheques. Two methods were applied to obtain the effective examples of noise prevention or noise reduction: reviewing existing research and interviewing key people with knowledge and experience that has not yet appeared in the literature. A range of cases of preventing the adverse effects of noise assessed before and after the intervention provide a number of good practices, including information and awareness-raising campaigns and the identification of key concepts and key players in the prevention of noise. The examples of good practice have been effective in reducing noise, reducing the effects of noise, increasing the awareness of the importance of noise reduction or increasing action to reduce noise. The examples are based on a common format for reviewing preventive measures and can serve as direct inspiration for action to prevent noise in children's daily settings.

Child↗
PubMed1992

Noise in multiple-workstation open-plan computer rooms: measurements and annoyance.

Computers in the workplace have become very prevalent. As with the introduction of any new technology, unanticipated problems often develop. Noise in open-plan computer rooms and annoyance and perceived deterioration in performance associated with it also appears to be a problem that may be similarly categorized. An experimental investigation was undertaken as a result of frequent user complaints about the difficulty of concentrating and performing their work in the computer rooms of a large service organization. Two typical computer rooms were investigated. Noise levels were measured at random times during the working hours. The noise spectrum was found to be almost similar in both facilities. The 10-second A-weighted noise level for all frequencies ranged between 53 and 62 dB. Most noise energy was either in the high-frequency bands (above 2,000 Hz) or low-frequency bands (below 500 Hz). The highest noise energy levels were recorded at 8,000 Hz (between 64 and 73 dB). Least noise energy levels were recorded between 500 and 2,000 Hz (between 35 and 44 dB). The noise spectrum, thus, was substantially different from those of open-plan offices. Eighty-nine percent of the users questioned indicated their tasks required concentration. Fifty percent of all respondents rated the noise level between extremely annoying and unbearable and intolerable (scale values between 22 and 25 on a 25-point scale; 1 being noticeable but not objectionable and 25 being unbearable and intolerable); 10% of the respondents considered the noise very annoying; 20% of the respondents considered the noise levels moderately annoying; the remaining respondents did not seem to have a major problem. Conversational sound and computer-printer beeping sounds were reported to be most annoying by 90% of the respondents who considered the noise levels annoying. Constant arrival and departure of users, sound from keyboards, and ventilation equipment also appeared to be major contributing factors.

Computer Terminals↗
PubMed2003

[Interaction between noise and ototoxic agents in the work environment].

There is a large number of well known substances, which exert an ototoxic effect in industrial settings. Ototoxic agents may be involved in many interactions with noise, the main factor responsible for the development of occupational hearing loss. Owing to the complexity of these relationships, their assessment is easier if controlled trials are carried out on animals. However, the results of experimental studies apply to high exposure levels, which are very rarely observed in industrial conditions. Data useful in estimating risks of hearing loss induced by industrial exposure are scarce. Until quite recently, the studies have focused on the combined effects of noise and chemicals of such groups as organic solvents, carbon monoxide or heavy metals. In the former group, a synergistic effects of noise and carbon disulfide as well as noise and toluene have been revealed at the cochlear level. Interactions between these chemicals and noise at the higher levels of the auditory system are most likely of an additive nature. Synergistic effect of carbon monoxide and noise may occur only at high concentrations of this substance. It is believed that the mechanism responsible for the interaction between carbon monoxide and noise depends on the hypoxemic effect of the former. A diminished access to oxygen exacerbates noise-induced metabolic disorders. However, it should be stressed that the nature of an interaction may be rather complex, because carbon monoxide (contrary to noise) also induces retrocochlear damage. As to the combined exposure to heavy metals and noise (range, 68-72 dB), the occurrence of cardiotoxic effects, not observed in single exposure to those agents, has been found in experimental studies. This may evidence a potentially wider range of possible interactions between toxic agents and noise not only in respect of the hearing organ. In further studies it seems essential to find out to what extent the effect of ototoxic agents should be taken into account in assessing the risk of hearing loss in industrial settings. If the effects of these agents in the work environment are taken into account then it will be necessary to verify the medical prevention criteria and hygiene norms regarding noise exposure.

Environment↗
PubMedDate not supplied

Environmental noise induced hearing loss in Nepal.

INTRODUCTION: Noise pollution in urban cities is a serious problem and steadily increasing over the years. This has direct and indirect affect to the people that can lead to the health hazard. OBJECTIVES: To find out environmental noise induced health effect on people residing in an urban community and to predict the risk of the environmental noise induced hearing loss. MATERIAL AND METHODS: One hundred fifty questionnaires were filled up for the environmental noise pollution survey. For the case control study, 36 exposed and 25 non-exposed residents of Kupondole were included. Based on the place of residence (main road and 20 min. walking distance from the main road), subjects were divided into exposed and non-exposed group concerning environmental noise. Demographic data and information about health problems was obtained by a structured interview. Audiometric test was performed using manual audiometer. Odds ratios (OR) and their 95% confidence intervals (95% CI) for noise induced hearing loss were estimated using logistic regression. Adjustment for occupational noise was done. RESULTS: The major health effect induced by the environmental noise was observed as lack of concentration followed by irritation, fatigue and headache. The crude OR and 95% CI for the exposed subjects was 4.2 (1.4, 12). After adjustment for occupational noise, the OR (95% CI) was 4.0 (1.2, 13). CONCLUSION: This study shows that exposure to noise causes wide range of health effects. For the exposed subjects there was an increased risk of noise induced hearing loss. The risk was significantly increased also after adjusting for occupational noise.

Adolescent↗
PubMed2006

[Measurement of personal noise exposure in a cold rolling mill].

OBJECTIVE: To measure and evaluate the personal noise exposure of cold rolling mill workers by using noise dosimeter. METHODS: According to job category and work type, all workers were divided into 11 groups. 3 to 5 day shift (8:00 to 16:00) workers from each group were selected as subjects for personal noise exposure measurement. SH-126 dosimeters were worn by each subject and collect noise data by a phone fix at collar. All subjects were asked to take notes about their working activities when they were wearing SH-126 dosimeters. Each worker's L(A)(eq) of 8 hours, geometric mean and range of each group were computed. RESULTS: There were many noise sources in the workshop. Recorded data showed that noise exposure of cold rolling mill was unstable. The varieties of personal noise levels were quite large. Among 53 workers, the highest noise exposure level was 100.0 dB (A), the lowest was 81.2 dB (A); the highest work type was of the foreside welders [94.20 dB (A)], and the lowest was of the straight-cutters [89.02 dB (A)]; quality checkers had the biggest rang [16.3 dB (A)], and primary rolling workers had the lest [2.3 dB (A)]. CONCLUSION: Noise exposure of all the 11 groups were more than 85 dB (A). Noise protection of these workers should be improved. It suggested that measuring personal noise exposure individually with dosimeters might obtain the noise exposure level more integrally in the complicated environment.

Environmental Monitoring↗
PubMed1995

[Noise signal reduction in cochlear implant speech processors].

Cochlear implant wearers suffer from an additional impairment of auditory-verbal communication due to environmental noise, similar to that experienced by many users of conventional hearing aids. To reduce this problem the mini-22 cochlear implant system has implemented a noise suppression function in the Mini Speech Processor (MSP) decreasing background noise-induced stimulation. The efficacy of this algorithm was investigated in 18 experienced postlingually-deafened adult cochlear implant users. By means of a computer-assisted speech intelligibility measurement unit, speech understanding was compared with and without the noise suppression function. Paired observations were conducted in noise as well as in silence. The recording of complete performance-intensity functions in terms of speech discrimination tested with the standardized Freiburg speech intelligibility test and a newly developed sentence test demonstrated the benefit of the noise reduction mechanism. Better understanding was achieved in silence in the normal speech processing mode of the MSP, whereas a significant improvement in noise resulted from the noise suppression. Considerable interindividual differences were found in the gain patients derived from using the noise suppression algorithm. The more often the S-position was used, the better the individual result with activated noise suppression. However, providing the cochlear implant patients with more information, as in the spectral peak ("SPEAK") stimulation strategy recently developed by Cochlear Corporation, could lead to higher speech discrimination scores in interfering noise. Paired comparison studies revealed that the new strategy added significantly to results of speech understanding. Average intelligibility rose 40% when using the new coding method instead of the MSP with activated noise suppression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Word recognition performance in continuous and interrupted broad-band noise by normal-hearing and simulated hearing-impaired listeners.

Word recognition performance was investigated in 12 normal-hearing young adults in continuous and interrupted broad-band noise as a function of signal-to-noise ratio (S:N) with and without a simulated high frequency hearing loss (i.e., low-pass filtered at 2000 Hz). Subjects exhibited conventional sigmoid performance-intensity functions in continuous noise, for both unfiltered and filtered conditions. In contrast, subjects demonstrated shallower performance-intensity functions in the interrupted noise conditions with overall superior performance under adverse signal-to-noise ratios relative to the continuous noise conditions. Separate two-way analyses of variances investigating mean word recognition performance differences as a function of normal listening (unfiltered) versus the simulated hearing loss (filtered). Signal-to-noise ratio for both continuous and interrupted noise conditions revealed a significant main effects for S:N with both noise conditions (p < .05) and a significant main effect for the simulated hearing loss only in the interrupted noise condition (p < .05). It was hypothesized that subjects' diminished performance in the interrupted noise condition with the stimulated high frequency hearing loss reflected a reduced ability to temporally resolve auditory information between the gaps of noise.

Adult↗
PubMedDate not supplied

Noise analysis of three newborn infant isolettes.

OBJECTIVE: The purpose of this study was to evaluate the noise of three newborn infant isolettes. STUDY DESIGN: An observational, prospective study evaluated noise in three isolettes (Ohmeda, Air Shields, and Drager). The study measured interior isolette noise production during quiet noise situations and isolette noise attenuation of added low- and high-frequency noise. Noise was measured on the decibel A scale and in the 125 Hz and 1000 Hz bands. RESULTS: During quiet conditions the Ohmeda and Drager isolettes had the least noise production on the basis of decibel A levels (p < 0.001). Low-frequency noise on the decibel A scale was attenuated the most by the Drager isolette (p < 0.001), although the overall difference may be clinically insignificant. The Ohmeda isolette attenuated high-frequency noise by 28.4 dB as measured on the decibel A scale, which was greater than values for the Drager (22.8 dB) and Air Shields (14 dB) isolettes (p < 0.001). CONCLUSIONS: High-frequency noise attenuation by the Ohmeda and Drager isolettes is clinically and statistically greater than high-frequency noise attenuation by the Air Shields isolette.

Evaluation Studies as Topic↗
PubMed1989

[Electronic noise compensation for improving speech discrimination in airplane pilots].

Noise exposure measurements were performed in pilots of the Federal Navy during realistic flight situations. The ambient noise levels during regular flight service were maintained at levels nearly all the time above 90 dB. To avoid occupational hearing loss, the "Noise Injury Prevention Code" issued by the insurers would demand wearing personal ear protection, e.g. ear plugs. But such equipment in the aircraft cockpit would have precisely the opposite effect, because one of the reasons for possible damage to hearing is radio communication. To be able to understand radio traffic in spite of the noisy environment, headphone volume must be raised above the noise of the engines. The use of ear plugs can be of only limited value. Whereas 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 traffic. Cockpit noise has its maximum intensity around 125 Hz and flight helmets and ear defenders are not very effective in low frequency ranges. Sennheiser electronic KG developed an active noise compensation circuit, which makes use of the "anti noise" principle. Here the outside noises picked up by two microphones integrated into the headset are processed electronically in such a way that they largely neutralise the original noise. It had to be made sure that the radio traffic signal was not also compensated and that the signal to noise ratio was clearly increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Aircraft↗