| 1. |
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| 2. |
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| 3. |
- Brännström, Jonas, et al.
(author)
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Clinical application of long-term intensity and pitch matches in fluctuating low-frequency hearing loss.
- 2008
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In: International Journal of Audiology. - : Informa UK Limited. - 1708-8186 .- 1499-2027. ; 47:7, s. 412-419
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Journal article (peer-reviewed)abstract
- The purpose of this study was to measure changes in intensity and pitch matches to better assess disease activity in fluctuating hearing loss. Long-term suprathreshold audiometry was carried out at home on a subject with a unilateral fluctuating low-frequency hearing loss during a period when the subject demonstrated no symptoms and a period when the subject reported hearing loss, aural pressure, and tinnitus. Daily measurements of binaural intensity and pitch matches were made. Day-to-day fluctuations were clearly accentuated during the period when the subject experienced symptoms. Specifically, deviations from the reference tone were only observed for binaural pitch matches at 1 kHz during the period without symptoms; however, highly fluctuating binaural intensity and pitch matches were observed at 0.25 kHz during the period with symptoms. These fluctuations were not observed in a normal-hearing group. The results suggest that long-term measurements of binaural intensity and pitch matches can be used to monitor disease activity in fluctuating low-frequency hearing loss.
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| 4. |
- Brännström, Jonas, et al.
(author)
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Effects on cochlear frequency selectivity after hypobaric pressure exposure.
- 2008
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In: The Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 1520-8524 .- 0001-4966. ; 123:5
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Journal article (peer-reviewed)abstract
- The effects of hypobaric pressure chamber exposure was measured in noise in ten patients with monaural fluctuating low-frequency hearing loss (FLFHL) such as Meniere's disease using psychophysical tuning curves (PTC), transiently evoked otoacoustic emissions (TEOAE), binaural pitch matches and speech recognition scores (SRS) in noise. In the literature, reversible hearing losses have been observed in about 50 % of the patients, but sometimes improved SRS can be observed in patients without hearing threshold improvement. This indicates possible effects of pressure treatment on cochlear frequency selectivity. The relative overpressure in the middle ear obtained after repeated exposures in hypobaric pressure chamber (total duration 18.5 to 28 minutes) was used to impose pressure gradients to the inner ear. The results indicated that the treatment effects were small, but slightly improved SRS in noise, TEOAEs emission strength and PTCs were observed after treatment. Pure tone hearing thresholds improved only for patients exposed to longer treatment durations. Subjective improvement at follow-up could not be predicted from the results. Although the effects were small, the data suggest that hypobaric pressure treatment may improve cochlear frequency selectivity in the affected ear in patients with monaural FLFHL.
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| 5. |
- Brännström, Jonas, et al.
(author)
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Long-term measurement of binaural intensity and pitch matches. II. Fluctuating low-frequency hearing loss.
- 2008
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In: International Journal of Audiology. - : Informa UK Limited. - 1708-8186 .- 1499-2027. ; 47:11, s. 675-687
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Journal article (peer-reviewed)abstract
- Thirteen subjects made consecutive long-term recordings of binaural intensity and pitch matches in their homes using portable equipment to assess hearing fluctuations. Two groups of subjects were used; one with monaural fluctuating low-frequency hearing loss (FLFHL) without vertigo, and one with monaural Meniere's disease (i.e. FLFHL with vertigo). The subjects measured binaural pitch matches using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear during one to several weeks. Their results were compared to those previously obtained from ten normal-hearing subjects. Both groups of subjects showed fluctuations in binaural intensity and pitch matches not seen in the normal-hearing group. We calculated the average day-to-day difference in matched intensity and frequency for each subject's test period as a measure of disease activity. This measure indicated that the group with Meniere's disease has a higher disease activity than the group with FLFHL without vertigo, and that both these groups of subjects had higher disease activity than normal-hearing subjects.
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| 6. |
- Brännström, Jonas, et al.
(author)
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Long-term measurement of binaural intensity matches and pitch matches. I. Normal hearing.
- 2008
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In: International Journal of Audiology. - : Informa UK Limited. - 1708-8186 .- 1499-2027. ; 47:2, s. 59-66
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Journal article (peer-reviewed)abstract
- Changes in pitch perception and hearing thresholds over time have been observed in subjects with monaural fluctuating low-frequency hearing loss and Ménière's disease. Long-term suprathreshold audiometry and binaural pitch matches could provide information of these changes. Ten normal subjects were tested for stability of binaural intensity and pitch matches during 9-22 days in their homes with newly developed portable test equipment. Binaural pitch matches were measured using a 0.25- or 1-kHz reference tone presented at 60 dB SPL to one ear, and a loudness-matched test tone of adjustable frequency presented to the other ear. The results showed stable binaural intensity matches (individual inter-quartile ranges, IQRs, 1.2 to 5.7 dB), but binaural pitch matches varied greatly (IQR -0.6 to 5.3% at 0.25 kHz; IQR -1.6 to 7.9% at 1 kHz). Binaural pitch-matching was much better in subjects who could define pitch precisely during monaural pitch matching. It was concluded that in future long-term evaluations of patients with fluctuating inner-ear function, binaural intensity matches could be suitable for all, but binaural pitch matching only for selected patients.
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| 7. |
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| 8. |
- Brännström, K J, et al.
(author)
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Hypobaric pressure exposure effects on cochlear frequency selectivity in fluctuating, low-frequency hearing loss.
- 2009
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In: Journal of Laryngology and Otology. - 1748-5460. ; 123, s. 710-717
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Journal article (peer-reviewed)abstract
- Aim:To study the effects of hypobaric pressure chamber exposure on the cochlear frequency selectivity of subjects with monaural, fluctuating, low-frequency hearing loss, such as occurs in Ménière's disease.Methods:We used a hypobaric pressure chamber to create relative underpressure in the ear canal, in order to impose positive pressure gradients on the inner ear. Psychophysical tuning curves, transiently evoked otoacoustic emissions and speech recognition scores in noise were measured in 10 subjects with fluctuating, low-frequency hearing loss, before and after pressure exposure.Results:After the exposure, subjects' overall pure tone averages showed no improvement, but individual results showed improved speech recognition scores in noise (six subjects), increased transiently evoked otoacoustic emission strength (three subjects) and increased psychophysical tuning curve steepness (two subjects). Deteriorations were also seen, mainly in psychophysical tuning curves. No association could be established between the different tests, and the measured parameters could not predict subjective improvement.Conclusion:The results suggest variable effects of hypobaric pressure exposure on inner-ear physiology.
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| 9. |
- Einarsson, Einar-Jon, et al.
(author)
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Long term hearing degeneration after platinum-based chemotherapy in childhood.
- 2010
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In: International Journal of Audiology. - : Informa UK Limited. - 1708-8186 .- 1499-2027. ; 49:10, s. 765-771
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Journal article (peer-reviewed)abstract
- The aim of this study was to investigate long-term development of hearing in subjects who had received platinum-based chemotherapy in childhood or adolescence. Another aim was to assess the self-reported hearing loss handicap and compare it to audiometric measurements. Medical records from individuals diagnosed with childhood cancer and treated with platinum-based chemotherapy between 1985 and 2000 at the University Hospital in Lund Sweden were reviewed retrospectively. Fifteen subjects, who fulfilled the eligibility criteria set for the study, underwent a thorough audiometric evaluation. The results show that the hearing loss, in subjects with ototoxicity had increased after the end of treatment, to include also the lower frequencies. The largest deterioration in hearing thresholds, up to 55 dB HL, was found at frequencies above 2 kHz. The findings also reveal that the subjects have a considerably greater hearing loss handicap and disability than would be expected from the results of the audiometric evaluations. The conclusion of this study is that children and adolescence treated with platinum-based chemotherapy should have regular audiometric follow-up examinations, also many years after the end of treatment. Furthermore, assessments of self-reported hearing disability should be made during and after chemotherapy.
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| 10. |
- Engervall, K, et al.
(author)
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Borreliosis as a cause of peripheral facial palsy: a multi-center study
- 1995
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In: ORL. - 0301-1569. ; 57:4, s. 202-206
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Journal article (peer-reviewed)abstract
- Borreliosis is known to be a common cause of peripheral facial palsy in Stockholm and its vicinity. The aim of the present study was to investigate the frequency and characteristics of borreliosis among patients with peripheral facial palsy in different parts of Sweden. All serological tests were performed in one laboratory. Ten Swedish Ear Nose and Throat clinics participated in a prospective 1-year study of patients seeking medical attention for acute peripheral facial palsy. Twenty-eight (6%) out of totally 446 patients fulfilled the criteria for the diagnosis of borreliosis. The frequency varied between 1 and 16% and was highest along the southeast coast of Sweden whereas no case was reported from the northern part of the country. Borreliosis was more common among children with facial palsy than among adults. The infection occurred during all seasons although it appears to be less frequent during the spring months. Only a minority of the borrelial patients had a history of a preceding tick bite or erythema migrans. The fairly low overall frequency of this secondary stage of borreliosis in the study may be a result of better knowledge of the disease and earlier treatment of its early manifestations. In Sweden's endemic areas borreliosis is a common cause of peripheral facial palsy, and therefore all patients with facial palsy in these regions should be examined for borrelial infection.
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| 11. |
- Grenner, Jan, et al.
(author)
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A comparison of wind noise in four hearing instruments
- 2000
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In: Scandinavian Audiology. - : Informa UK Limited. - 0105-0397. ; 29:3, s. 171-174
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Journal article (peer-reviewed)abstract
- Wind noise was measured in four behind-the-ear hearing instruments with different microphone openings. A silent airflow of 7 m/s was directed toward the ear of a Kemar head and the resulting wind noise was measured. The amplification was set to an insertion gain of 35 dB at 1.6 kHz. The wind noise amplitude at the position of the drum ranged from 84 to 97 dB(A). The hearing instrument with a partially covered microphone entrance proved best, whereas one with an open microphone entrance had the poorest performance. A reduction in wind noise of 6-17 dB could be achieved in all hearing instruments by using a simple windscreen made of Styrofoam. The windscreen affected the frequency response by less than 2 dB. By subtracting the insertion gain from the wind noise, an equivalent wind noise could be presented as a function of frequency. A considerable difference was found between the wind noise sensitivity in different hearing instruments. All could be improved by a windscreen without adversely affecting the frequency response.
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| 12. |
- Grenner, Jan, et al.
(author)
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Action potential threshold elevation in the guinea-pig as a function of impact noise exposure energy
- 1988
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In: Audiology. - : Informa UK Limited. - 0020-6091. ; 27:6, s. 356-366
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Journal article (peer-reviewed)abstract
- Eighteen groups of guinea pigs were exposed to a simulated impact noise for periods of 1.5-24 h. The peak level was kept constant at 131.5 dB and the repetition rate was varied to give seven different equivalent levels (Leq) between 96 and 117 dB. The auditory thresholds were assessed by electrocochleography after 1 month and compared with those of a control group. Significant damage occurred even at the lowest exposure energy used. When the total exposure energy was expressed on a decibel scale, the threshold elevation (1-10 kHz) increased 1.07 dB for each decibel increase in the exposure energy, regardless of the combination of Leq and exposure time. The results of the study thus support the equal-energy hypothesis under these conditions.
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| 13. |
- Grenner, Jan, et al.
(author)
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AP threshold elevation in the guinea pig following exposure to a broadband noise
- 1989
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In: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 1520-8524 .- 0001-4966. ; 86:6, s. 2223-2228
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Journal article (peer-reviewed)abstract
- Sixty guinea pigs were exposed to a steady-state broadband noise with a falling frequency spectrum. The sound-pressure level was varied between 96 and 117 dB SPL, and the duration of the exposure was varied from 3 to 12 h. After 4-5 weeks, the auditory thresholds were determined by electrocochleography at 14 frequencies, and the results were compared with a control group. With increasing sound-pressure level, the thresholds became elevated at all frequencies. The maximum threshold elevation also exhibited a slight shift toward higher frequencies. With increasing exposure time, the threshold elevations increased and shifted into the high-frequency region, whereas the low-frequency region was less affected. Linear regression analysis showed that the average threshold elevation between 1 and 20 kHz did not deviate from that predicted by the equal-energy hypothesis. However, the high-frequency loss at 5-20 kHz was very dependent on the exposure time, whereas the 1- to 4-kHz loss was not. There was no sign of any critical intensity with sudden increments in threshold elevation.
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| 14. |
- Grenner, Jan
(author)
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Comments on Zazzio's Hyperacusis Study.
- 2012
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In: Photomedicine and Laser Surgery. - : Mary Ann Liebert Inc. - 1549-5418 .- 1557-8550. ; 30:7, s. 400-400
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Journal article (peer-reviewed)
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| 15. |
- Grenner, Jan, et al.
(author)
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Hearing thresholds in four-year-old children with weak or no transient-evoked otoacoustic emissions
- 1997
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In: Scandinavian Audiology. - : Informa UK Limited. - 0105-0397. ; 26:2, s. 107-111
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Journal article (peer-reviewed)abstract
- Play audiometry is part of the general developmental screening covering 4-year-old children in the city of Malmo (Sweden). In an open study, 10% of the cohort was tested with transient-evoked otoacoustic emissions (TEOAEs), using the ILO88 system. The aim was to reveal a hearing loss exceeding 25 dB HL in 4-year-old children. As the first step in determining whether emissions can be used as an efficient method of screening for hearing loss, 295 children were tested with TEOAEs. Audiometry was performed in 160 children. Audiometry was not performed if the TEOAEs were strong (> or = 10 dB SPL) in both ears. In the group with TEOAEs of 8.8dB SPL or greater, all ears tested with audiometry had a pure-tone average (PTA) of 25 dB HL or better. Twenty-one percent of the ears had TEOAEs < or = 0 dB SPL. Only 9% of the ears had a hearing threshold exceeding 25 dB HL (PTA). In conclusions, the number of pathological TEOAE results was much larger than the number of pathological audiograms, making TEOAEs too sensitive to use as a single screening test, but the method may be used as first-line screening.
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| 16. |
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| 17. |
- Grenner, Jan, et al.
(author)
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Long-term measurements using home audiometry with Békésy’s technique
- 2017
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In: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 56:3, s. 202-211
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Journal article (peer-reviewed)abstract
- Objective: To examine the efficacy of fixed-frequency Békésy’s home audiometry to assess hearing fluctuation and treatment outcomes in patients with subjectively fluctuating hearing loss. Design: SMAPH, a software audiometry program for Windows, was installed and calibrated on laptop computers. Békésy’s audiometry was carried out daily in the patients’ homes, using sound-attenuating earphones. Study sample: Seventeen patients with previously or currently subjectively fluctuating hearing loss. Five patients received of treatment for their conditions during the measurement period. Results: Measurement periods ranged from 6 to 60 days. Varying degrees of compliance were seen, some patients measuring less than 50% of the days, others measuring every day. Based on their long-term measurements the patients were classified into three groups: patients with stable recordings, with fluctuating low-frequency hearing loss, or with fluctuating high-frequency hearing loss. In the patients with stable recordings, significant test–retest differences were seen below 10 dB at frequencies 0.125–8 kHz. Conclusions: Home audiometry with Békésy’s technique can be used to evaluate disease activity and to monitor hearing results after therapy.
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| 18. |
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| 19. |
- Grenner, Jan, et al.
(author)
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Noise-induced threshold elevation as a function of peak sound pressure level
- 1990
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In: Hearing Research. - 0378-5955. ; 46:1-2, s. 161-169
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Journal article (peer-reviewed)abstract
- Thirty-three groups of guinea pigs, consisting of five animals in each group, were exposed to a simulated impact noise with peak levels ranging between 119.5 and 134.5 dB SPL. By varying the repetition rate, different equivalent levels could be set at each peak level. The equivalent levels ranged from 96 to 117 dB SPL, and the exposure duration was 1.5 to 24 hours. The compound action potential thresholds were measured in 1/3-octave steps between 1 and 20 kHz, one month after the exposure. Higher peak levels resulted in a peak-shaped threshold elevation with a maximum around 8 kHz. For constant peak levels, the equal energy theory was supported. For exposures of equal energy but different peak levels, significantly higher threshold elevations resulted after exposure to higher peak levels.
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| 20. |
- Grenner, Jan, et al.
(author)
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Right-left correlation in guinea pig ears after noise exposure
- 1990
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In: Acta Oto-Laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 109:1-2, s. 41-48
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Journal article (peer-reviewed)abstract
- In order to investigate whether experimental material consisting of noise-exposed animals should be regarded as 'ears' or 'animals', a comparison was made between the permanent threshold shifts in the right and left ears in 53 groups of noise-exposed guinea-pigs, with 5 animals in each group. The action potential (N1) thresholds were measured at fourteen frequencies in both ears. In the noise-exposed animals, the threshold elevations were up to 40 dB. The average right-left correlation coefficient within each group was about 0.79, regardless of noise energy. The degree of correlation was significantly greater after impact noise than after continuous noise. As a consequence of the high right-left correlation, the informative value of measuring a second ear in the same animal was, in our experiments, only 11% of that of the first one. No correlation could be found between the degree of skin pigmentation and the threshold elevation.
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| 21. |
- Grenner, Jan
(author)
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Significance of a notch in the otoacoustic emission stimulus spectrum.
- 2012
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In: Journal of Laryngology and Otology. - 1748-5460. ; 126:9, s. 897-901
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Journal article (peer-reviewed)abstract
- Objective: To explain a clinical observation: a notch in the stimulus spectrum during transient evoked otoacoustic emission measurement in ears with secretory otitis media. Methods: The effects of tympanic under-pressure were investigated using a pressure chamber. A model of the ear canal was also studied. Results: Tympanic membrane reflectance increased as a consequence of increased stiffness, causing a notch in the stimulus spectrum. In an adult, the notch could be clearly distinguished at an under-pressure of approximately -185 daPa. The sound frequency of the notch corresponded to a wavelength four times the ear canal length. The ear canal of infants was too short to cause a notch within the displayed frequency range. The notch was demonstrated using both Otodynamics and Madsen equipment. Conclusion: A notch in the otoacoustic emission stimulus spectrum can be caused by increased stiffness of the tympanic membrane, raising suspicion of low middle-ear pressure or secretory otitis media. This finding is not applicable to infants.
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| 22. |
- Konradsson, Konrad, et al.
(author)
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Electrocochleographic and audiometric evaluation of hypobaric effect in Meniere's disease
- 1999
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In: Laryngoscope. - 1531-4995. ; 109:1, s. 59-64
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Journal article (peer-reviewed)abstract
- OBJECTIVES: To elucidate the effects of hypobaric pressure on cochlear hydrodynamics in patents with well-defined Meniere's disease. DESIGN: Sixteen patients were consecutively selected. Elevated hearing threshold levels and pathological transtympanal electrocochleography (tt-ECOG) were confirmed at the day of trial. The patients were exposed to repeated episodes of hypobaric pressure in a pressure chamber. The rate (20 daPa/s) and magnitude (-285 daPa) of chamber pressure change were low. The induced tympanic overpressure (+185 daPa) was continuously monitored and any tympanic equilibration was avoided. METHODS: The results of Bekesy and speech audiometry as well as tt-ECOG performed immediately before and after exposure were compared. The importance of chamber pressure change, number of hypobaric episodes, duration of exposure, and the induced relative tympanic overpressure was tested. RESULTS: It is shown that the relative tympanic overpressure is the most important factor to affect the cochlear hydrodynamics. Higher relative overpressure was associated with improvement of hearing threshold levels, while the ECOG results tended to improve with lower induced tympanic overpressure. CONCLUSION: The importance of tympanic overpressure shown in this study is in agreement with previous findings from hypobaric animal experiments. The inverse relation of psychoacoustic and ECOG tests suggests that the two methods evaluate different parameters, perhaps contributing differently to the physiology of hearing.
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| 23. |
- Konradsson, Konrad, et al.
(author)
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Tympanic pressure gradients and otoacoustic emissions
- 1999
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In: Ear and Hearing. - 1538-4667. ; 20:5, s. 403-403
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Journal article (peer-reviewed)abstract
- OBJECTIVE: The purpose of this study was to investigate the immediate effects of tympanic over- and under-pressure, induced by variations in ambient pressure on click-evoked otoacoustic emissions (CEOAEs) in healthy individuals. It was of particular interest to elucidate whether changes in the CEOAE response in both spectral and time domains could be attributed not only to tympanic, but also to cochlear influence. DESIGN: Nine healthy subjects with normal hearing and middle ear pressure were exposed to ambient pressure changes in a pressure chamber. The pressure was progressively changed in 100 daPa steps to accomplish an increase and a decrease in tympanic pressure. Pressure equilibration of the middle ear was avoided. The relative tympanic over- and under-pressure (+/- 320daPa) was monitored by tympanometry and the CEOAEs recorded at every step of tympanic pressure change. RESULTS: There was a statistically significant reduction of the otoacoustic emission (OAE) response levels and reproducibility already at 100 daPa of ambient pressure change. The OAE response was progressively reduced by increased pressure gradients. The CEOAEs recorded during progressive tympanic over- and under-pressure also had increasingly shorter latencies. These changes of the OAE response characteristics were most pronounced in the 750 to 3000 Hz frequency bands. CONCLUSIONS: The progressive attenuation of the OAE response and the concomitant shortening of the OAE response latencies were observed during a combination of altered middle and inner ear pressure. Although the middle and inner ear influence cannot be separated we suggest, based on our findings, that the shortening of latencies may partly be caused by inner ear pressure changes and stiffening of the labyrinthine membranes. Further studies are needed to more specifically clarify the relative contribution of the tympanic and labyrinthine influence, respectively, for the various aspects of pressure influence on the OAE response.
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| 24. |
- Latifpour, David Homayoun, et al.
(author)
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The effect of a new treatment based on somatosensory stimulation in a group of patients with somatically related tinnitus.
- 2009
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In: The international tinnitus journal. - 0946-5448. ; 15:1, s. 94-99
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Journal article (peer-reviewed)abstract
- The aim of this study was to evaluate the effect of a new treatment consisting of stretching, posture training, and auricular acupuncture immediately and at a 3-month followup. This method has not been tested previously. From an original pool of 41 potential subjects, we recruited 24 (12 men, 12 women; ages 18-70 years) into this study and divided them from a waiting list into either a treatment group or a control group. We measured mobility of neck and posture; measured severity of tinnitus by the Klockhoff test and the visual analog scale (VAS); and measured grade of anxiety and depression with the Hospital Anxiety and Depression Scale. We also used the Mann-Whitney U-test to determine statistical significance. The statistical analysis demonstrated a significant decrease of tinnitus in the treatment group as compared with the control group, according to the VAS before and after treatment (p < .001) and at follow-up after 3 months (p < .01). We also observed a significant decrease of tinnitus according to the Klockhoff test before and after treatment (p < .001) and at follow-up after 3 months (p < .01). Our study indicates that this method, based on somatosensory stimulation, may be a useful and alternative treatment of somatic tinnitus.
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| 25. |
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| 26. |
- Minja, B M, et al.
(author)
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Chronic suppurative otitis media in Tanzanian school children and its effects on hearing
- 2006
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In: East African Medical Journal. - 0012-835X. ; 83:6, s. 5-322
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Journal article (peer-reviewed)abstract
- OBJECTIVES: To compare different treatment regimens of chronic suppurative otitis media (CSOM) in school children, in regard to their consequence in hearing and discharge from the ear drum perforation. DESIGN: Randomised controlled trial. SETTING: Randomly selected primary schools within Dar es Salaam. SUBJECTS: Three hundred and twenty eight children between 5-17 years of age with CSOM in one or both ears. RESULTS: Three to four months after the onset of treatment 31% of group 1, 54% of group 2, and 56% of group 3, had dry ears. Treatment with dry mopping and boric acid in alcohol ear drops was significantly better than dry mopping alone. Adding amoxicillin to the treatment did not improve the end results. Hearing test performed before and after treatment showed that the hearing thresholds were the same or better after the treatment. The possible risk that boric acid in alcohol ear drops should lead to sensorineural hearing loss has not been confirmed. CONCLUSION: Based on the above results, the treatment of choice for CSOM in children in Dar es Salaam should be dry mopping and boric acid in spirit ear drops.
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| 27. |
- Nilsson, P, et al.
(author)
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Impulse noise and continuous noise of equivalent frequency spectrum and total sound energy
- 1987
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In: Acta Oto-Laryngologica. Supplement. - : Informa UK Limited. - 0365-5237 .- 0001-6489 .- 1651-2251. ; 104:S 441, s. 45-58
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Journal article (peer-reviewed)abstract
- It has been proposed that impulse noise and continuous noise affect the inner ear differently and investigations have found impulse noise to be harmful to both the inner hair cells and the outer hair cells. Scanning electron microscopy and non-standard methods for statistical analysis have facilitated the evaluation of different types of morphological changes after exposure to various kinds of noise. Morphological differences were compared in groups of guinea pigs exposed to either impulse noise or continuous noise of equivalent duration, spectral content and energy. Functionally, the groups also showed similar threshold elevations. In order to separate the two groups, subtle hair cell changes were recorded and evaluated either alone, in combination with each other or with hair cell loss. It was found that both the inner hair cells and the outer hair cells were affected differently by impulse noise than by continuous noise even though the auditory thresholds were similar.
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| 28. |
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| 29. |
- Rydmarker, S, et al.
(author)
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Impulse noise of different durations
- 1987
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In: Acta Oto-Laryngologica. Supplement. - : Informa UK Limited. - 0365-5237 .- 0001-6489 .- 1651-2251. ; 104:S 441, s. 3-23
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Journal article (peer-reviewed)abstract
- This paper describes a comparison between auditory threshold elevations and morphological cochlear changes evaluated with scanning electron microscopy in order to identify cochlear defects in guinea pigs exposed to impulse noise of varying durations. There was a significant difference in the auditory threshold shifts between animals exposed for 3 and 12 hours. Hair cell loss is generally used as a morphological correlate to noise-induced hearing loss. Minor stereocilia changes, quantified with non-standard statistical methods have been used as a complement. Morphologically, it was not possible to separate cochleas exposed to impulse noise for 3 and 12 hours when only lost hair cells were evaluated. Quantitative evaluation of subtle morphological changes are valuable in the correlation of noise-induced hearing loss with morphologic changes.
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| 30. |
- Tideholm, B, et al.
(author)
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Continuous 24-hour measurement of middle ear pressure
- 1996
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In: Acta Oto-Laryngologica. - 1651-2251. ; 116:4, s. 581-588
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Journal article (peer-reviewed)abstract
- A new method was developed for continuous measurement of the middle ear pressure during a 24-h period. The equipment consisted of a piezo-electric pressure device and a digital memory. To allow continuous pressure recordings during normal every-day activities the equipment was made light and portable. The measurement accuracy of the equipment as well as the base-line and temperature stability were tested and found to meet to our requirements satisfactorily. In 4 volunteers with different middle ear conditions, a small perforation was made through the tympanic membrane. A rubber stopper containing a small polyethylene tube was fitted into the external ear canal. Tubal function tests were made to establish the equipment's ability to monitor fast pressure changes. The tests were well in accordance with other methods of direct pressure measurements. The equipment was carried by the volunteers for 24 h to monitor any slow or rapid dynamic pressure changes in the middle ear. Four continuous 24-h measurements are presented. The method was found to be suitable for valid measurements of dynamic pressure changes in the middle ear during normal every-day activities. It may become a useful instrument in the search for a better understanding of the development of chronic middle ear disease.
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