In-vivo assessment of osseous versus non-osseous transmission pathways of vibratory stimuli applied to the bone and the dura in humans

Publication date: Available online 28 September 2018

Source: Hearing Research

Author(s): Reto Stump, Ivo Dobrev, Niklaus Krayenbühl, Rudolf Probst, Christof Röösli

Abstract

Background

Bone conduction (BC) is an alternative to air conduction (AC) for stimulation of the inner ear. Stimulation for BC can occur directly on the skull bone, on the skin covering the skull bone, or on soft tissue (i.e., eye, dura). All of these stimuli can elicit otoacoustic emissions (OAE). This study aims to compare OAEs generated by different combinations of stimuli in live humans, including direct stimulation of the intracranial contents via the dura, measured intraoperatively.

Methods

Measurements were performed in five normal-hearing ears of subjects undergoing a neurosurgical intervention with craniotomy in general anesthesia. Distortion product OAEs (DPOAEs) were measured for f₂ at 0.7, 1, 2, 3, 4, and 6 kHz with a constant ratio of the primary frequencies (f₂/f₁) of 1.22. Sound pressure L₁ was held constant at 65 dB SPL, while L₂ was decreased in 10 dB steps from 70 to 30 dB SPL. A DPOAE was considered significant when its level was ≥6 dB above the noise floor. Emissions were generated sequentially with different modes of stimulation: 1) pre-operatively in the awake subject by two air-conducted tones (AC-AC); 2) within the same session preoperatively by one air- and one bone-conducted tone on the skin-covered temporal bone as in audiometry (AC-BC); 3) intra-operatively by one air-conducted tone and one bone-vibrator tone applied directly on the dura (AC-DC). A modified bone vibrator (Bonebridge; MED-EL, Innsbruck, Austria) was used for BC stimulation on the dura or skin-covered mastoid. Its equivalent perceived SPL was calibrated preoperatively for each individual by psychoacoustically comparing the level of a BC tone presented to the temporal region to an AC tone at the same frequency. Simultaneously with the DPOAEs, vibrations at the teeth were measured with an accelerometer attached using a custom-made holder.

Results

It was possible to record DPOAEs for all three stimulation modes. For AC-DC, DPOAEs were not detected above the noise floor below 2 kHz but were detectable at the higher frequencies. The best response was measured at or above 2 kHz with L₂ = 60 dB SPL. The acceleration measured at the teeth for stimulation on the dura was lower than that for stimulation on the bone, especially below 3 kHz.

Conclusion

We demonstrate a proof-of-concept comparison of DPOAEs and teeth acceleration levels elicited by a bone vibrator placed either against the skin-covered temporal bone, as in audiometry, or directly against the dura mater in patients undergoing a craniotomy. It was demonstrated that DPOAEs could be elicited via non-osseous pathways within the skull contents and that the required measurements could be performed intra-operatively.

from #Audiology via ola Kala on Inoreader https://ift.tt/2y8PKNd
via IFTTT

In-vivo assessment of osseous versus non-osseous transmission pathways of vibratory stimuli applied to the bone and the dura in humans

Publication date: Available online 28 September 2018

Source: Hearing Research

Author(s): Reto Stump, Ivo Dobrev, Niklaus Krayenbühl, Rudolf Probst, Christof Röösli

Abstract

Background

Bone conduction (BC) is an alternative to air conduction (AC) for stimulation of the inner ear. Stimulation for BC can occur directly on the skull bone, on the skin covering the skull bone, or on soft tissue (i.e., eye, dura). All of these stimuli can elicit otoacoustic emissions (OAE). This study aims to compare OAEs generated by different combinations of stimuli in live humans, including direct stimulation of the intracranial contents via the dura, measured intraoperatively.

Methods

Measurements were performed in five normal-hearing ears of subjects undergoing a neurosurgical intervention with craniotomy in general anesthesia. Distortion product OAEs (DPOAEs) were measured for f₂ at 0.7, 1, 2, 3, 4, and 6 kHz with a constant ratio of the primary frequencies (f₂/f₁) of 1.22. Sound pressure L₁ was held constant at 65 dB SPL, while L₂ was decreased in 10 dB steps from 70 to 30 dB SPL. A DPOAE was considered significant when its level was ≥6 dB above the noise floor. Emissions were generated sequentially with different modes of stimulation: 1) pre-operatively in the awake subject by two air-conducted tones (AC-AC); 2) within the same session preoperatively by one air- and one bone-conducted tone on the skin-covered temporal bone as in audiometry (AC-BC); 3) intra-operatively by one air-conducted tone and one bone-vibrator tone applied directly on the dura (AC-DC). A modified bone vibrator (Bonebridge; MED-EL, Innsbruck, Austria) was used for BC stimulation on the dura or skin-covered mastoid. Its equivalent perceived SPL was calibrated preoperatively for each individual by psychoacoustically comparing the level of a BC tone presented to the temporal region to an AC tone at the same frequency. Simultaneously with the DPOAEs, vibrations at the teeth were measured with an accelerometer attached using a custom-made holder.

Results

It was possible to record DPOAEs for all three stimulation modes. For AC-DC, DPOAEs were not detected above the noise floor below 2 kHz but were detectable at the higher frequencies. The best response was measured at or above 2 kHz with L₂ = 60 dB SPL. The acceleration measured at the teeth for stimulation on the dura was lower than that for stimulation on the bone, especially below 3 kHz.

Conclusion

We demonstrate a proof-of-concept comparison of DPOAEs and teeth acceleration levels elicited by a bone vibrator placed either against the skin-covered temporal bone, as in audiometry, or directly against the dura mater in patients undergoing a craniotomy. It was demonstrated that DPOAEs could be elicited via non-osseous pathways within the skull contents and that the required measurements could be performed intra-operatively.

from #Audiology via ola Kala on Inoreader https://ift.tt/2y8PKNd
via IFTTT

In-vivo assessment of osseous versus non-osseous transmission pathways of vibratory stimuli applied to the bone and the dura in humans

Publication date: Available online 28 September 2018

Source: Hearing Research

Author(s): Reto Stump, Ivo Dobrev, Niklaus Krayenbühl, Rudolf Probst, Christof Röösli

Abstract

Background

Bone conduction (BC) is an alternative to air conduction (AC) for stimulation of the inner ear. Stimulation for BC can occur directly on the skull bone, on the skin covering the skull bone, or on soft tissue (i.e., eye, dura). All of these stimuli can elicit otoacoustic emissions (OAE). This study aims to compare OAEs generated by different combinations of stimuli in live humans, including direct stimulation of the intracranial contents via the dura, measured intraoperatively.

Methods

Measurements were performed in five normal-hearing ears of subjects undergoing a neurosurgical intervention with craniotomy in general anesthesia. Distortion product OAEs (DPOAEs) were measured for f₂ at 0.7, 1, 2, 3, 4, and 6 kHz with a constant ratio of the primary frequencies (f₂/f₁) of 1.22. Sound pressure L₁ was held constant at 65 dB SPL, while L₂ was decreased in 10 dB steps from 70 to 30 dB SPL. A DPOAE was considered significant when its level was ≥6 dB above the noise floor. Emissions were generated sequentially with different modes of stimulation: 1) pre-operatively in the awake subject by two air-conducted tones (AC-AC); 2) within the same session preoperatively by one air- and one bone-conducted tone on the skin-covered temporal bone as in audiometry (AC-BC); 3) intra-operatively by one air-conducted tone and one bone-vibrator tone applied directly on the dura (AC-DC). A modified bone vibrator (Bonebridge; MED-EL, Innsbruck, Austria) was used for BC stimulation on the dura or skin-covered mastoid. Its equivalent perceived SPL was calibrated preoperatively for each individual by psychoacoustically comparing the level of a BC tone presented to the temporal region to an AC tone at the same frequency. Simultaneously with the DPOAEs, vibrations at the teeth were measured with an accelerometer attached using a custom-made holder.

Results

It was possible to record DPOAEs for all three stimulation modes. For AC-DC, DPOAEs were not detected above the noise floor below 2 kHz but were detectable at the higher frequencies. The best response was measured at or above 2 kHz with L₂ = 60 dB SPL. The acceleration measured at the teeth for stimulation on the dura was lower than that for stimulation on the bone, especially below 3 kHz.

Conclusion

We demonstrate a proof-of-concept comparison of DPOAEs and teeth acceleration levels elicited by a bone vibrator placed either against the skin-covered temporal bone, as in audiometry, or directly against the dura mater in patients undergoing a craniotomy. It was demonstrated that DPOAEs could be elicited via non-osseous pathways within the skull contents and that the required measurements could be performed intra-operatively.

from #Audiology via ola Kala on Inoreader https://ift.tt/2y8PKNd
via IFTTT

In-vivo assessment of osseous versus non-osseous transmission pathways of vibratory stimuli applied to the bone and the dura in humans

Publication date: Available online 28 September 2018

Source: Hearing Research

Author(s): Reto Stump, Ivo Dobrev, Niklaus Krayenbühl, Rudolf Probst, Christof Röösli

Abstract

Background

Bone conduction (BC) is an alternative to air conduction (AC) for stimulation of the inner ear. Stimulation for BC can occur directly on the skull bone, on the skin covering the skull bone, or on soft tissue (i.e., eye, dura). All of these stimuli can elicit otoacoustic emissions (OAE). This study aims to compare OAEs generated by different combinations of stimuli in live humans, including direct stimulation of the intracranial contents via the dura, measured intraoperatively.

Methods

Measurements were performed in five normal-hearing ears of subjects undergoing a neurosurgical intervention with craniotomy in general anesthesia. Distortion product OAEs (DPOAEs) were measured for f₂ at 0.7, 1, 2, 3, 4, and 6 kHz with a constant ratio of the primary frequencies (f₂/f₁) of 1.22. Sound pressure L₁ was held constant at 65 dB SPL, while L₂ was decreased in 10 dB steps from 70 to 30 dB SPL. A DPOAE was considered significant when its level was ≥6 dB above the noise floor. Emissions were generated sequentially with different modes of stimulation: 1) pre-operatively in the awake subject by two air-conducted tones (AC-AC); 2) within the same session preoperatively by one air- and one bone-conducted tone on the skin-covered temporal bone as in audiometry (AC-BC); 3) intra-operatively by one air-conducted tone and one bone-vibrator tone applied directly on the dura (AC-DC). A modified bone vibrator (Bonebridge; MED-EL, Innsbruck, Austria) was used for BC stimulation on the dura or skin-covered mastoid. Its equivalent perceived SPL was calibrated preoperatively for each individual by psychoacoustically comparing the level of a BC tone presented to the temporal region to an AC tone at the same frequency. Simultaneously with the DPOAEs, vibrations at the teeth were measured with an accelerometer attached using a custom-made holder.

Results

It was possible to record DPOAEs for all three stimulation modes. For AC-DC, DPOAEs were not detected above the noise floor below 2 kHz but were detectable at the higher frequencies. The best response was measured at or above 2 kHz with L₂ = 60 dB SPL. The acceleration measured at the teeth for stimulation on the dura was lower than that for stimulation on the bone, especially below 3 kHz.

Conclusion

We demonstrate a proof-of-concept comparison of DPOAEs and teeth acceleration levels elicited by a bone vibrator placed either against the skin-covered temporal bone, as in audiometry, or directly against the dura mater in patients undergoing a craniotomy. It was demonstrated that DPOAEs could be elicited via non-osseous pathways within the skull contents and that the required measurements could be performed intra-operatively.

from #Audiology via ola Kala on Inoreader https://ift.tt/2y8PKNd
via IFTTT

Longitudinal analysis of leisure noise exposure among adolescents with special focus on portable listening devices: the OHRKAN cohort study.

Related Articles

Longitudinal analysis of leisure noise exposure among adolescents with special focus on portable listening devices: the OHRKAN cohort study.

Int J Audiol. 2018 Sep 27;:1-9

Authors: Dreher A, Weilnhammer V, Gerstner D, Hendrowarsito L, Twardella D, Reiter C, Perez-Alvarez C, Steffens T, Herr C, Heinze S

Abstract
The aim was to investigate leisure noise exposure and sociodemographic determinants of risky leisure noise exposure over five years in 2148 students visiting grade 9 of any school type in a German city from 2009-2011. Within the OHRKAN cohort study, leisure noise exposure was calculated from literature-retrieved sound pressure levels (SPLs) and self-reported duration of 18 leisure activities at baseline and two follow-ups. Risky exposure was defined as exceeding 85 dB(A) averaged over a 40-h-week. Determinants of risky total leisure noise (TLN) exposure and risky exposure to portable listening devices (PLDs) were investigated using generalised estimating equations (GEEs). Up to 73% of students exceeded noise levels of 85 dB(A) at some timepoint. The noise exposure and importance of different leisure activities changed with increasing age. Risky exposure to TLN and PLDs was associated with lower education, single parent households and being male. Risky PLD exposure was additionally associated with a migrant background. Current prevention measures for leisure noise exposure must be extended to at-risk groups. Besides enhancing campaigns in lower education schools, acoustical insulation in sports halls, noise warnings on tools or in videogames could address especially men. Migrants need education about healthy PLD use in their native language if necessary.

PMID: 30261779 [PubMed - as supplied by publisher]

from #Audiology via ola Kala on Inoreader https://ift.tt/2QeZGMr
via IFTTT

Hearing and ear status of Pacific children aged 11 years living in New Zealand: the Pacific Islands families hearing study.

Related Articles

Hearing and ear status of Pacific children aged 11 years living in New Zealand: the Pacific Islands families hearing study.

Int J Audiol. 2018 Sep 27;:1-10

Authors: Purdy SC, Taylor S, Schluter PJ, Tautolo ES, Iusitini L, Ahmad Z, Sundborn G, Paterson J

Abstract
This study aimed to determine the prevalence of hearing loss and ear problems in Pacific children, and investigate current and past demographic, health and social factors potentially associated with hearing and ear problems. A cross-sectional observational study design nested within a birth cohort was employed. Nine-hundred-twenty Nine-hundred-twenty Pacific children aged 11 years were audiologically assessed. Using average hearing thresholds at 500, 1k and 2k Hz, 162 (18%) right and 197 (21%) left ears had ≥20 dB hearing loss. Hearing loss was mild (20-39 dB) in most cases; 2% of ears had moderate to moderate-severe (40-69 dB) hearing loss. However, only 101 (11%) children had normal peripheral hearing defined by passing hearing threshold, tympanogram and distortion product otoacoustic emission assessments. Those with confirmed middle ear disease at age 2 years had significantly increased odds of a non-Type A tympanogram (adjusted odds ratio: 2.00; 95% confidence interval: 1.56, 2.50) when re-assessed at age 11 years. Hearing loss, abnormal tympanograms, and auditory processing difficulties were present in many Pacific children. Interventions are also urgently needed to mitigate the effect of the longstanding ear disease likely to be present for many Pacific children.

PMID: 30261774 [PubMed - as supplied by publisher]

from #Audiology via ola Kala on Inoreader https://ift.tt/2zErzbg
via IFTTT

Assessing auditory nerve condition by tone decay in deaf subjects with a cochlear implant.

Related Articles

Assessing auditory nerve condition by tone decay in deaf subjects with a cochlear implant.

Int J Audiol. 2018 Sep 27;:1-8

Authors: Wasmann JA, van Eijl RHM, Versnel H, van Zanten GA

Abstract
The condition of the auditory nerve is a factor determining hearing performance of cochlear implant (CI) recipients. Abnormal loudness adaptation is associated with poor auditory nerve survival. We examined which stimulus conditions are suitable for tone decay measurements to differentiate between CI recipients with respect to their speech perception. Tone decay was defined here as occurring when the percept disappears before the stimulus stops. We measured the duration of the percept of a 60-s pulse train. Current levels ranged from below threshold up to maximum acceptable loudness, pulse rates from 250 to 5000 pulses/s, and duty cycles (percentages of time the burst of pulses is on) from 10% to 100%. Ten adult CI recipients were included: seven with good and three with poor speech perception. Largest differences among the subjects were found at 5000 pulses/s and 100% duty cycle. The well performing subjects had a continuous percept of the 60-s stimulus within 3 dB above threshold. Two poorly performing subjects showed abnormal loudness adaptation, that is, no continuous percept even at levels greater than 6 dB above threshold. We conclude that abnormal loudness adaptation can be detected via an electric tone decay test using a high pulse rate and 100% duty cycle.

PMID: 30261773 [PubMed - as supplied by publisher]

from #Audiology via ola Kala on Inoreader https://ift.tt/2QgQgQw
via IFTTT