| 61. |
- Hällgren, Mathias, 1972-, et al.
(författare)
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Speech understanding in quiet and noise, with and without hearing aids
- 2005
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Ingår i: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 44:10, s. 574-583
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Tidskriftsartikel (refereegranskat)abstract
- Speech recognition and cognitive functions important for speech understanding were evaluated by objective measures and by scores of perceived effort, with and without hearing aids. The tests were performed in silence, and with background conditions of speech spectrum random noise and ordinary speech. One young and one elderly group of twelve hearing-impaired subjects each participated. Hearing aid use improved speech recognition in silence (7 dB) and in the condition with speech as background (2.5 dB S/N), but did not change the perceived effort scores. In the cognitive tests no hearing aid benefit was seen in objective measures, while there was an effect of hearing aid use in scores of perceived effort, subjects reported less effort. There were no age effects on hearing aid benefit. In conclusion, hearing aid use may result in reduced effort in listening tasks that is not associated with improvement in objective scores. © 2005 British Society of Audiology, International Society of Audiology, and Nordic Audiological Society.
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| 62. |
- Johansson, Magnus, 1973-, et al.
(författare)
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Binaural masking level difference for speech signals in noise
- 2002
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Ingår i: International Journal of Audiology. - 1499-2027 .- 1708-8186. ; 41:5, s. 279-284
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the binaural masking level difference in both detection and recognition of speech embedded in noise when the signal is phasc-shifted 180░ between the left and the right ear. Swedish spondaic words masked by noise were presented binaurally to 10 normally hearing subjects. The results are presented in terms of speech detection threshold, speech recognition threshold, a psychometric function of speech recognition versus signal-to-noise ratio, and speech intelligibility as a function of binaural intelligibility level difference. Both specch detection threshold and speech intelligibility improved when the speech signal was phase-shifted 180░. The binaural intelligibility level difference ranged from 5.7 to 7.7 dB.
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| 63. |
- Johansson, Magnus, et al.
(författare)
-
Hearing threshold levels for an otologically unscreened, non-occupationally noise-exposed population in Sweden
- 2002
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Ingår i: International Journal of Audiology. - 1499-2027. ; 41:3, s. 180-194
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the hearing threshold levels (HTL) of an otologically unscreened population in Sweden. The results are compared to other studies of otologically unscreened populations, and a new mathematical model of hearing threshold levels as a function of age is presented. The subjects were males and females aged from 19 to 81 years, selected from the province of ╓sterg÷tland in Sweden. The test battery included otoscopy, tympanometry, pure-tone audiometry, and a questionnaire. Subjects exposed to occupational noise were excluded, and in total 603 persons were included in the analysis. The regression analysis resulted in different hyperbolic tangent functions with four parameters: HTL = A + B ╫ tanh(C ╫ age + D).
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| 64. |
- Johansson, Magnus, 1973-
(författare)
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On noise and hearing loss : Prevalence and reference data
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Noise exposure is one of the most prevalent causes of irreversible occupational disease in Sweden and in many other countries. In hearing conservation programs, aimed at preventing noise-induced hearing loss, audiometry is an important instrument to highlight the risks and to assess the effectiveness of the program. A hazardous working environment and persons affected by it can be identified by monitoring the hearing thresholds of individual employees or groups of employees over time. However, in order to evaluate the prevalence of occupational noise-induced hearing loss, relevant reference data of unexposed subjects is needed.The first part of this dissertation concerns the changes in hearing thresholds over three decades in two occupational environments with high noise levels in the province of Östergötland, Sweden: the mechanical and the wood processing industries. The results show a positive trend, with improving median hearing thresholds from the 1970s into the 1990s. However, the hearing loss present also in the best period, during the 1990s, was probably greater than if the occupational noise exposure had not occurred. This study made clear the need for a valid reference data base, representing the statistical distribution of hearing threshold levels in a population not exposed to occupational noise but otherwise comparable to the group under study.In the second part of the dissertation, reference data for hearing threshold levels in women and men aged from 20 to 79 years are presented, based on measurements of 603 randomly selected individuals in Östergötland. A mathematical model is introduced, based on the hyperbolic tangent function, describing the hearing threshold levels as functions of age. The results show an age-related gender difference, with poorer hearing for men in age groups above 50 years.The prevalence of different degree of hearing loss and tinnitus is described for the same population in the third part of the dissertation. The overall prevalence of mild, moderate, severe or profound hearing loss was 20.9% collectively for women and 25.0% collectively for men. Tinnitus was reported by 8.9% of the women and 17.6% of the men. Approximately 2.4% of the subjects under study had been provided with hearing aids. However, about 7.7% were estimated to potentially benefit from hearing aids as estimated from their degree of hearing loss.Noise-induced hearing loss primarily causes damage to the outer hair cells of the inner ear. The fourth and last part of the dissertation evaluates the outer hair cell function, using otoacoustic emission measurements (OAE). Prevalence results from three different measuring techniques are presented: spontaneous otoacoustic emissions (SOAE), transient evoked otoacoustic emissions (TEOAE) and distortion product otoacoustic emissions (DPOAE). Gender and age effects on the recorded emission levels were also investigated. Women showed higher emission levels compared to men and for both women and men the emission levels decreased with increasing age. The results from the OAE recordings were shown to be somewhat affected by the state of the middle ear. The study included tympanometry, and the relation of the outcome ofthis test to the otoacoustic emissions is described, where high middle ear compliance resulted in low emission level. Reference data for the tympanometric measurements are also presented.The results of this project form an essential part of the important work against noiseinduced hearing loss, which needs continuous monitoring. The reference data presented here will provide a valid and reliable data base for the future assessment of hearing tests performed by occupational health centres in Sweden. This data base will in turn prove useful for comparison studies for Sweden as a responsible fellow EU member country setting high standards for work force safety. The statistical distribution of hearing threshold levels as a function of age for men and women in tabulated form is available on the Swedish Work Environment Authority (Arbetsmiljöverket) web site: http://www.av.se/publikationer/bocker/fysiskt/h293.shtm.
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| 65. |
- Johansson, Magnus, et al.
(författare)
-
Otoacoustic emissions and tympanometry in a general adult population in Sweden
- 2003
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Ingår i: International Journal of Audiology. - 1499-2027. ; 42:8, s. 448-464
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Tidskriftsartikel (refereegranskat)abstract
- The present study concerns a general adult population in Sweden, not exposed to hazardous occupational noise. Tympanometry and spontaneous (SOAE), transient evoked (TEOAE) and distortion-product (DPOAE) otoacoustic emissions were investigated in 493 randomly selected men and women aged from 20 to 79 years. Effects of gender, age, ear side and middle ear state were determined, with and without adjusting for hearing threshold level. No statistically significant effects on middle ear pressure or compliance were present. For TEOAEs and DPOAEs, the effect of gender and age was statistically significant (p < 0.01), with larger signal levels for female subjects and young subjects, even after adjusting for hearing threshold level. No effect of middle ear pressure on otoacoustic emissions was present, but high middle ear compliance was associated with low emission levels (p < 0.01). Reference data for middle ear compliance and pressure and prevalence data on SOAEs, TEOAEs and DPOAEs for male and female subjects in different age groups were determined. Mean signal levels of TEOAEs and DPOAEs are presented.
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| 66. |
- Johansson, Magnus, et al.
(författare)
-
Prevalence of hearing impairment in a population in Sweden
- 2003
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Ingår i: International Journal of Audiology. - 1499-2027. ; 42:1, s. 18-28
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Tidskriftsartikel (refereegranskat)abstract
- An epidemiological study was carried out, based on 590 randomly selected subjects, aged from 20 to 80 years, in the province of Ostergötland in Sweden. The results obtained were similar to published results from other countries, with an overall prevalence of subjects with average hearing threshold levels over the frequencies 0.5, 1, 2 and 4 kHz (M4) equal to or exceeding 25 dB HL for the better ear (BE) of 16.9% (95% CI: 13.819.9%). For M4 BE > or = 35 dB HL, the prevalence was 7.7% (95% CI: 5.5-9.8%), for M4 BE > or = 45 dB HL, the prevalence was 3.3% (95% CI: 1.9-4.8%), and for M4 BE > or = 65 dB HL, the prevalence was 0.2% (95% Cl: 0.0-0.6%). The overall prevalence of reported tinnitus was 13.2% (95% CI: 10.5-16.0%). In the population under study, 7.7% of the subjects were estimated to benefit from a hearing aid, while the prevalence of hearing aid users was 2.4%.
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| 67. |
- Johansson, Magnus, 1973-, et al.
(författare)
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Reference data for evaluation of occupationally noise-induced hearing loss
- 2004
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Ingår i: Noise & Health. - 1463-1741 .- 1998-4030. ; 6:24, s. 35-41
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Tidskriftsartikel (refereegranskat)abstract
- Relevant reference data are required in order to determine the effect from occupational noise exposure on hearing. Pure-tone averages (PTA) of hearing threshold levels simplify the evaluation for audiometric frequencies typically affected by noise. The present study provides reference data of high frequency (HF) PTA over 3, 4 and 6 kHz for a general adult population, aged from 20 to 79 years, not exposed to hazardous occupational noise. The results are presented as statistical distributions of HF PTA values as functions of age, and as prevalence of different degree of HF PTA in the age groups 20-29, 30-39, 40-49, 50-59, 60-69 and 70-79 years.
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| 68. |
- Johansson, Magnus, et al.
(författare)
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The development of noise-induced hearing loss in the Swedish County of Östergötland in the 1980s and the 1990s
- 2001
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Ingår i: Noise & Health. - 1463-1741. ; 3:10, s. 15-28
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Tidskriftsartikel (refereegranskat)abstract
- This retrospective cross-sectional study of median hearing threshold levels of males employed in two specific occupations shows that the trend with decreasing noise-induced hearing loss in Sweden during the 1970s and 1980s continues into the 1990s. In the occupational categories mechanical work and wood processing men in age groups 30-39, 40-49 and 50-59 years old examined during the time period 1971-76, 1981-86 and 1991-96 were compared. Possible explanations to the improvement might be a wider use of hearing protectors at work and less exposure to noise during military service. The results show that the awareness of noise-induced occupational hearing loss has improved but the hearing conservation programs are still necessary as hearing threshold levels in these occupational groups continue to be poorer than expected in relation to age.
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| 69. |
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| 70. |
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