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PubMedDate not supplied

The maximum permissible ambient noise and frequency-specific averaging time on the measurement of distortion product otoacoustic emissions.

The effects of ambient noise and averaging time on distortion product otoacoustic emission (DPOAE) measurements were systematically examined in 20 normally hearing adults. For each frequency from 0.7 to 6 kHz, 2f1-f2 DPOAEs were measured at nine intensity levels of ambient noise for each of four different averaging times. The dependent variable of interest was the DPOAE:noise ratio (D:N)--the relationship between DPOAE amplitude and noise level at 2f1-f2. Findings indicated that, relative to the baseline condition (25 dBA), ambient noise levels of 40 dBA or greater affected the D:N considerably in the lower frequencies. However, noise levels of 55-65 dBA did not affect the D:N in the higher frequencies. Results also indicated that, to achieve detectable DPOAEs, longer averaging times were required as ambient noise increased and as frequency decreased. Based on the results, the maximum permissible ambient noise levels (MPANLs) were estimated in relation to averaging time.

Acoustic Stimulation↗
PubMed1982

Sentences for testing speech intelligibility in noise.

A list of ten spoken Swedish sentences was computer edited to obtain new lists with exactly the same content of sound, but with new sentences. A noise was synthesized from the speech material by the computer to produce exactly the same spectrum of speech and noise. The noise was also amplitude modulated by a low frequency noise to make it sound more natural. This material was tested monaurally on 20 normal-hearing subjects. The equality in intelligibility of some of the lists was investigated. Repeated threshold measurements in noise showed a standard deviation of 0.44 dB when the learning effect was outbalanced. Only a small part of the learning effect was due to learning of the word material. Intelligibility curves fitted to the data points in noise and without noise showed maximum steepnesses of 25 and 10%/dB respectively. At constant signal to noise ratio (S/N) the best performance was achieved at a speech level of 53 dB.

Adolescent↗
PubMed1990

Effect of noise on word discrimination by subjects with impaired hearing, compared with those with normal hearing.

A comparison was made of the discrimination ability of different groups of hearing-impaired and normal-hearing subjects in noisy conditions. Four groups of subjects having a sensorineural hearing loss with various audiogram configurations, one group of subjects having a conductive hearing loss and one group of normal-hearing subjects were chosen. The submaster tapes were recorded in quiet and in pink noise with signal-to-noise ratios of -3, -8, and -13 dB. The test subjects heard the test words monaurally via earphones. The best speech discrimination was achieved in quiet, anechoic conditions. As the noise level increased, speech discrimination decreased. Subjects with sensorineural hearing loss were more adversely affected by noise than subjects with normal hearing or with conductive hearing loss. However, at high noise levels, their speech discrimination was poorer than that of normal-hearing subjects. Persons with a high-frequency hearing loss, cut-off point 1 kHz, suffered in noise similarly to those with sloping or flat hearing losses. In quiet and in moderate noise, the speech discrimination of subjects with a conductive hearing loss and subjects with normal hearing was similar, while at high noise levels, subjects with conductive hearing losses achieved better discrimination than normal-hearing subjects.

Adolescent↗
PubMed1996

Evaluation of noise in hearing instruments caused by GSM and DECT mobile telephones.

The annoyance of noise in hearing instruments caused by electromagnetic interference from Global Systems for Mobile Communication (GSM) and Digital European Cordless Telecommunication (DECT) mobile telephones has been subjectively evaluated by test subjects. The influence on speech recognition from the GSM and DECT noises was also determined. The measurements involved 17 hearing-impaired subjects. The annoyance was tested with GSM and DECT noise, each one mixed with continuous speech, a mall environment noise, or an office environment noise. Speech recognition was tested with the DANTALE word material mixed with GSM and DECT noise. The listening test showed that if noise level is acceptable so also is speech recognition. The results agree well with an investigation carried out on normal-hearing subjects. If a hearing instrument user is to be able to use a telephone without annoyance, the input-related noise level must not exceed 47 dB SPL for GSM and 46 dB SPL for DECT.

Adult↗
PubMed1997

Normal and hearing-impaired word recognition scores for monosyllabic words in quiet and noise.

The effects of noise on word recognition scores were assessed with normal-hearing and hearing-impaired subjects. Fifty-one normal-hearing subjects were tested at 50 dB HL using signal-to-noise ratios (S/Ns) of 5, 10, and 15 dB. Thirty subjects with mild-to-moderate sensorineural hearing losses were tested in quiet and in noise at S/Ns of 10 dB and 15 dB. Monosyllabic words in a Multitalker Noise were selected for testing. Mean scores for the normal-hearing subjects were 45% at the 5 dB S/N, 74% at the 10 dB S/N, and 87% at the 15 dB S/N. For the hearing-impaired subjects, scores were 85% in quiet, 60% at the 15 dB S/N, and 40% at the 10 dB S/N. These results suggest that background noise which is mildly disruptive for normal hearing subjects can be highly disruptive to hearing-impaired subjects. Moreover, these findings indicate that subjects with mild-to-moderate sensorineural hearing loss require a more favourable S/N than normal listeners to achieve comparable word recognition scores. Test-retest differences for word recognition scores revealed variability that agreed closely with predictions based on the binomial distribution for both groups of subjects. Speech-in-noise abilities must be measured directly because regression equations revealed that speech-in-noise scores cannot be predicted accurately from either puretone thresholds or speech-in-quiet scores. Word recognition functions are presented from several hearing-impaired subjects and demonstrate the value of testing in noise.

Adolescent↗
PubMed2006

Acceptance of noise with monaural and binaural amplification.

The present study investigated the effects of monaural and binaural amplification on speech understanding in noise and acceptance of noise for 39 listeners with hearing impairment. Results demonstrated that speech understanding in noise improved with binaural amplification; however, acceptance of noise was not dependent on monaural or binaural amplification for most listeners. These results suggest that although two hearing aids maximize speech understanding ability in noise, most individuals' acceptance of noise, which is directly related to hearing aid use, may not be affected by the use of binaural amplification. It should be noted that monaural amplification resulted in greater acceptance of noise for some listeners, indicating that binaural amplification may negatively affect some individuals' willingness to wear hearing aids. It should also be noted that interaural differences in acceptance of noise might exist for some listeners; therefore, if only one hearing aid is fitted, monaural ANLs should be measured.

Adult↗
PubMed1990

[Audiological evaluation of the middle ear implant--speech discrimination under noise circumstances].

Speech discrimination scores under noise circumstances were studied by use of the middle ear implant (MEI) and the conventional hearing aid (HA, HA-33, RION, Co, Ltd). The studies were performed in 10 patients implanted with the MEI and in 12 adult volunteers with normal hearing as a control. The tests were carried out using Japanese monosyllabic lists from 57S-speech discrimination test list as a test sound and multi-talker noise as a noise source. A speaker was placed in front of a subject in one meter apart. Sound characteristics of HA were adjusted as far as possible to those of the MEI by use of a sound equalizer. The intensity of speech sound pressure was adjusted at 65dB SPL, while that of the noise was changed to 65, 70 and 75dB SPL in the position of patients. Audiological evaluation of the MEI, the HA and control obtained by percentages of correct answers to 50 words in speech discrimination test with and without noise (65, 70, 75dB SPL). When the test was performed without noise, speech discrimination scores by the MEI and the HA were either 96.8 +/- 3.6% and 94.8 +/- 4.1%. However, under noise circumstances (65dB SPL) that by both devices were either 81.6 +/- 9.1% and 66.8 +/- 10.6% (P less than 0.001). When the intensity of the noise increased to 70 and 75dB SPL, speech discrimination scores by both devices deprecated together with consistent difference (P less than 0.01). Moreover speech discrimination scores by the MEI were almost same as control.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Impulse noise and hand-arm vibration in relation to sensory neural hearing loss.

The present study was carried out to determine whether impulse noise and simultaneous exposure to noise and vibration can aggravate sensory neural hearing loss (SNHL) among forest (N = 199) and shipyard (N = 171) workers. The average level of exposure to noise outside the used earmuffs and the average exposure over time were nearly equal for the two groups. The impulsiveness of the noise and the average exposure level inside the earmuffs were measured with a miniature microphone. The hearing threshold of the workers was measured at 4 kHz and then estimated according to Robinson's model to compare the observed and expected hearing loss. The impulsiveness of the noise was greater both outside and inside the earmuffs in shipyard work than in forest work. The average SNHL was higher than predicted for the shipyard workers and about the same as predicted for the forest workers. The total exposure level inside the earmuffs was influenced by the total wearing time. The low frequencies of the chain-saw noise were not attenuated sufficiently by the earmuffs to protect the workers' hearing. The present study suggests that exposure to impulse noise increases the risk of SNHL, but that simultaneous exposure to hand-arm vibration and noise does not.

Ear Protective Devices↗
PubMed2005

Long-term effect of occupational noise on the risk of coronary heart disease.

OBJECTIVES: The aim of the study was to investigate the short- and long-term effects of occupational exposure to continuous and impulse noise on the risk of CHD. METHODS: The effect of noise on CHD was studied among 6005 Finnish middle-aged industrially employed men (part of the screeners in the Helsinki Heart Study) in a prospective 18-year follow-up study. The CHD end points (codes 410-414 in the ninth revision of the International Classification of Diseases and codes I20-I25 in the tenth revision) were obtained from official Finnish registers. The Finnish job-exposure matrix FINJEM provided estimates of the proportion of exposed persons and the mean level of exposure among those exposed by occupation. The relative risks (RR) of CHD and the 95% confidence intervals (95% CI) for noise exposure were calculated from Cox's proportional hazard models with adjustment for some other risk factors of CHD. RESULTS: The short-term (9-year follow-up) relative risk of CHD for the combined noise (continuous noise exceeding 80 decibels and impulse noise) was 1.38 (95% CI 1.04-1.82), and the long-term (18-year follow-up) RR was 1.54 (95% CI 1.28-1.86). For blue-collar workers the corresponding estimates were 1.11 (95% CI 0.82-1.51) and 1.29 (95% CI 1.05-1.57). Adjustment for other relevant risk factors did not materially change the results. CONCLUSIONS: In our long-term follow-up of industrially employed men, exposure to noise, especially to impulse noise, was associated with a moderate, but statistically significant increase in CHD risk that persisted even after the workers had passed the age of retirement.

Adult↗
PubMed1999

Noise assessment during aircraft run-up procedures.

BACKGROUND: A comprehensive noise survey was conducted at Oficinas Gerais de Material Aeronautico (OGMA), Alverca, Portugal, and at several Portuguese Air Force (PoAF) bases, as part of an ongoing occupational noise assessment program. The major objectives consisted of measuring and analyzing noise radiated by various types of military aircraft while undergoing maintenance, repair, or testing. METHODS: Amplitude, frequency, time history and statistical analysis were conducted on noise emitted by aircraft during run-up procedures. Analysis and evaluation used various noise indexes (Leq and Lmax), frequency spectra, and sound pressure time histories for the assessment of noise exposure on the employees during their working life span. RESULTS: The results show a predominance of large pressure amplitudes within the lower frequency bands. This was correlated with long-term clinical observations in these workers. This study corroborates the definition of vibroacoustic disease as a systemic, noise-induced occupational pathology caused by long-term (>10 yr) exposure to large pressure amplitude (> or = 90 dB SPL) and low frequency (< or = 500 Hz) noise.

Aerospace Medicine↗
PubMed1999

Sister chromatid exchange analysis in workers exposed to noise and vibration.

BACKGROUND: There has been a growing interest in the combined effects of noise and vibration. In a population of aeronautical workers diagnosed with vibroacoustic disease (VAD), a large incidence of malignancy was detected. These workers were exposed to large pressure amplitude (LPA) (> or = 90 dB SPL) noise, with energy content concentrated within the low frequency (LF) bands (< or = 500 Hz) and whole-body vibration (WBV). To our knowledge, there are no studies conducted in humans or animals that address the issue of the potential genotoxic effects of vibration combined with noise. In the present study, the levels of sister chromatid exchanges (SCE) and of cells with high frequencies of SCE (HFC) were analyzed in peripheral blood lymphocytes of workers employed in various occupations within the aeronautical industry. METHODS: SCE and HFC were analyzed in lymphocytes of 50 workers occupationally exposed to noise and vibration and of 34 office-worker controls (G0). The exposed group included: 10 hand-vibrating tool operators (G1), 15 engine test cell technicians (G2), 12 aircraft run-up technicians (G3) and 13 Portuguese Air Force helicopter pilots (G4). Groups 2-4 were exposed to WBV and LPALF noise; group 1 was exposed to LPA high frequency noise and local vibration. Statistical analysis of the mean SCE count per cell was carried out by multiple regression analysis comparing various predictor variables: type of exposure, duration of exposure, age, and cigarette consumption. RESULTS: Only cigarette consumption and type of exposure were found to be significantly correlated with the mean SCE frequency. After allowing for the effects of smoking, the analysis indicates that: 1) there was no significant difference between G1 and G0 (p > 0.05); 2) the differences between G2 and G0, G3 and G0, G4 and G0 were all highly significant (p < 0.001); 3) there was no significant difference between G2 and G3 (p > 0.05), nor between G2 and G3 combined and G4 (p > 0.05); and 4) G2 and G4 combined had a significantly elevated mean SCE frequency compared G0 (p < 0.001). Statistical analysis of the proportion of HFC was consistent with these results. CONCLUSION: Our data suggest that occupational exposure to LPALF noise and WBV may lead to increased levels of SCE in men. These results also suggest a reason for the high incidence of malignancy in VAD patients. The observed effects may not reflect a direct action of these physical agents on DNA. Alternative explanations may lie in the noise-, vibration-, and/or stress-induced pathophysiological changes.

Adult↗
PubMed1999

[Assessment of otoacoustic emission usefulness for early detection of hearing impairment caused by noise].

74 miners, aged 19-35, exposed to industrial noise were examined by means of otoacoustic emission (TEOAE). The group was divided into 3 subgroups depending on the time of noise exposure. Significant weakening of otoacoustic emission in all subgroups was observed, even in subgroup with the shortest time of noise exposition and normal audiogram. The results were confirmed by others authors. Otoacoustic emission (TEOAE) could be very useful in early detection of hearing impairment cause by noise. 74 miners, aged 19-35, exposed to industrial noise were examined by means of otoacoustic emission (TEOAE). The group was divided into 3 subgroups depending on the time of noise exposure. Significant weakening of otoacoustic emission in all subgroups was observed, even in subgroup with the shortest time of noise exposition and normal audiogram. The results were confirmed by others authors. Otoacoustic emission (TEOAE) could be very useful in early detection of hearing impairment cause by noise.

Acoustic Stimulation↗
PubMed2002

[A study on the effects of contralateral acoustic suppression to transient evoked otoacoustic emissions after noise exposure].

OBJECTIVE: To investigate the effects of contralateral acoustic suppression(CAS) on transient evoked otoacoustic emissions(TEOAE) in Noise Exposure Condition, in order to explore the effects of efferent positive feedback regulation on the cochlear mechanisms and the effects of CAS on the sensitivity of TEOAE measure for finding changes of cochlear function condition induced by noise exposure. METHOD: Observing the effects of CAS (60 dB SPL WN) on the changes of TEOAE parameters, Response Amplitude, Reproducibility, Band SNR and Band Reproducibility, before and after noise exposure. RESULT: The values of every index of TEOAE were decreased respectively so that the effects of noise exposure on cochlear function can be reflected sensitively. A small decrease of values can be induced by CAS before noise exposure, of some decrease of indices were significant. After noise exposure, the changes of TEOAE parameters become much more with CAS than without. CONCLUSION: Noise exposure can effect obviously cochlear function condition and decrease OAE measurement values. CAS had suppressing action on cochlear activity by a negative feedback and can increase obviously the sensitivity of TEOAE measurement in finding the changes induced by noise exposure.

Adult↗
PubMed1999

[The effects of salicylate on noise-induced hearing loss in the guinea pig].

OBJECTIVE: To investigate the effects of salicylate on noise-induced hearing loss (NIHL) in guinea pigs. METHODS: The animals were allocated into four groups (salicylate + noise, saline + noise, noise only and salicylate only) and were exposed to a 4 kHz octave band noise at 105 dB SPL for 2 hours for 5 consecutive days. Dynamic changes of ABR thresholds evoked by clicks were monitored. After physiological examination, the cochleae were processed for the morphological examination by light microscopy. RESULTS: Mean thresholds of ABRs in the experimental group obtained on 5th day of the noise exposure was positively lower than the control groups (P < 0.05). The similar trends of ABR changes were found during other exposure days and after exposure, but the differences were not statistically significant. In the experimental group, there were 37.00 +/- 8.89 hair cell loses as assessed by nucleus staining, and 3.20 +/- 1.07 hair cells with nuclear deformation. The noise group had 74.11 +/- 10.28 hair cell loses and 10.43 +/- 9.71 hair cells with nuclear deformation, whereas the saline group had 63.60 +/- 7.97 hair cell loses and 20.80 +/- 15.48 hair cells with nuclear deformation. The difference between two groups was significant (P < 0.05). CONCLUSION: The results suggest that administration of salicylate facilitates the recovery of cochlear hearing and reduces damage to hair cells after noise exposure.

Animals↗
PubMed1992

[Effect of noise on blood pressure of various types of rats].

Before the experiment, male Wistar rats were divided into two types (A and B) according to the different responses of their ECG and Heart Rate (HR) to 1 hour noise exposure: in type A, the ST segment elevated and HR decreased significantly during the exposure; in type B, both ST segment and HR showed no considerable variation. We exposed type A and B wistar rats and spontaneously hypertensive rats (SHRs) of 105 dB steady-state noise, 4 hours per day, 6 days per week. The results showed that after 3 weeks of noise exposure, the mean systolic blood pressure (BP) of type A rats was significantly higher than that of type B and control rats. This higher BP retained progressively till the end of observation (35 weeks); while there were not significant changes of BP in type B rats during the period of 35 weeks noise exposure. We also found that when exposed to noise for 14 weeks, the SHRs in exposure group had markedly higher mean systolic BP than those in control group. The results indicated that noise may affect BP of both Wistar rats and SHRs. There is probably a difference in the susceptibility of BP response to noise. The susceptibility of the BP of rats in type A to noise is greater than that of rats in type B.

Animals↗
PubMed1977

[Discrimination and critical signal to noise ratio of normal and pathological hearing (author's transl)].

With reference to the cocktail party situation the selective hearing of normal and pathological hearing was examined during a period of monaural or binaural noise representation. To describe the physiological situation we modified the physical definition of the signal to noise ratio adding the word "critical". Procedure of examination: Hearing level and speech intensity for maximum discrimination of numbers, monosyllables and sentences was evaluated. The speech intensity level defined by these measurements was fixed while the noise level was raised till speech discrimination was reduced to 35-45%. This value is characteristic for the critical signal to noise ratio. A second measurement examined the change of the critical signal to noise ratio by representing the same noise to the contralateral ear. Thus noise is lateralized in the middle of the head and speech discrimination is better in normal hearing compared to the monaural situation. Results of normal and pathological hearing are discussed and dependences between selective hearing and critical signal to noise ratio are shown.

Audiometry↗
PubMed2003

[Effects of noise on antioxidant enzymes of cochlea in guinea pigs].

OBJECTIVE: To investigate the effect of noise on the antioxidant enzymes of cochleae. METHODS: 16 male pigmented guinea pigs (250 - 300 g) were randomly divided into 2 groups, control group and noise group. Each group had 8 animals. The animals in noise group were performed auditory evoked brainstem responses (ABR) recording before and after exposure to a continuous noise (4 kHz, octave band, 100 dB, SPL) 8 h/d for 3 consecutive days. Immediately at the end of the third day's noise exposure after ABR recording, guinea pigs were decapitated. Both the right and the left cochlea with the bony capsule removed were homogenized, and the supernatants were prepared for assays. Reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were measured. RESULTS: ROS level of the noise group [(281.2 +/- 3.5) U/mg pro] was significantly higher than that of the control group [(273.0 +/- 3.2) U/mg pro, P < 0.05] and SOD, CAT and GSH-Px activities of the noise group [(206.5 +/- 5.1) NU/mg pro, (47.0 +/- 9.0) U/g pro, (14.1 +/- 2.5) U/mg pro respectively] were significantly lower than that of the control group [(221.8 +/- 4.8) NU/mg pro, (60.8 +/- 9.9) U/g pro, (21.1 +/- 3.1) U/mg pro respectively, P < 0.05]. CONCLUSION: Noise may damage the defensive system of antioxidant enzymes in cochlea.

Animals↗
PubMed2004

Speech intelligibility with helicopter noise: tests of three helmet-mounted communication systems.

BACKGROUND: Military aviator helmet communications systems are designed to enhance speech intelligibility (SI) in background noise and reduce exposure to harmful levels of noise. Some aviators, over the course of their aviation career, develop noise-induced hearing loss that may affect their ability to perform required tasks. New technology can improve SI in noise for aviators with normal hearing as well as those with hearing loss. METHODS: SI in noise scores were obtained from 40 rotary-wing aviators (20 with normal hearing and 20 with hearing-loss waivers). There were three communications systems evaluated: a standard SPH-4B, an SPH-4B aviator helmet modified with communications earplug (CEP), and an SPH-4B modified with active noise reduction (ANR). RESULTS: Subjects' SI was better in noise with newer technologies than with the standard issue aviator helmet. A significant number of aviators on waivers for hearing loss performed within the range of their normal hearing counterparts when wearing the newer technology. The rank order of perceived speech clarity was 1) CEP, 2) ANR, and 3) unmodified SPH-4B. CONCLUSIONS: To insure optimum SI in noise for rotary-wing aviators, consideration should be given to retrofitting existing aviator helmets with new technology, and incorporating such advances in communication systems of the future. Review of standards for determining fitness to fly is needed.

Adult↗