Maturation of Mechanical Impedance of the Skin-Covered Skull: Implications for Soft Band Bone-Anchored Hearing Systems Fitted in Infants and Young Children

Mackey, Allison; Hodgetts, William E.; Scott, Dylan K.; Small, Susan A.

doi:10.1097/aud.0000000000000272

Cited by 10 publications

(5 citation statements)

References 40 publications

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“…However, their impedances are around 5 dB lower overall at 1 kHz compared to the current results. The current results at the mastoid are within 2 dB from the impedances of the mastoid with 2 N static force of adults in Mackey et al (2016). Moreover, Mackey et al (2016) showed that the mastoid mechanical impedance with 5.4 N static force was 3 to 5 dB higher than with 2 N static force in adults.…”

Section: Mechanical Point Impedancementioning

confidence: 49%

“…The current results at the mastoid are within 2 dB from the impedances of the mastoid with 2 N static force of adults in Mackey et al (2016). Moreover, Mackey et al (2016) showed that the mastoid mechanical impedance with 5.4 N static force was 3 to 5 dB higher than with 2 N static force in adults. Consequently, the slightly lower impedances for the mastoid reported here compared to Flottorp and Solberg (1976) and Håkansson et al (1986) is likely an effect of the lower static force used in the current study.…”

Section: Mechanical Point Impedancementioning

confidence: 67%

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Hearing Through Bone Conduction Headsets

2023

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Bone conduction (BC) stimulation has mainly been used for clinical hearing assessment and hearing aids where stimulation is applied at the mastoid behind the ear. Recently, BC has become popular for communication headsets where the stimulation position often is close to the anterior part of the ear canal opening. The BC sound transmission for this stimulation position is here investigated in 21 participants by ear canal sound pressure measurements and hearing threshold assessment as well as simulations in the LiUHead. The results indicated that a stimulation position close to the ear canal opening improves the sensitivity for BC sound by around 20 dB but by up to 40 dB at some frequencies. The transcranial transmission ranges typically between −40 and −25 dB. This decreased transcranial transmission facilitates saliency of binaural cues and implies that BC headsets are suitable for virtual and augmented reality applications. The findings suggest that with BC stimulation close to the ear canal opening, the sound pressure in the ear canal dominates the perception of BC sound. With this stimulation, the ear canal pathway was estimated to be around 25 dB greater than other contributors, like skull bone vibrations, for hearing BC sound in a healthy ear. This increased contribution from the ear canal sound pressure to BC hearing means that a position close to the ear canal is not appropriate for clinical use since, in such case, a conductive hearing loss affects BC and air conduction thresholds by a similar amount.

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Section: Mechanical Point Impedancementioning

confidence: 49%

Section: Mechanical Point Impedancementioning

confidence: 67%

Hearing Through Bone Conduction Headsets

2023

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“…The output properties of BCDs are affected by the mechanical impedance of the load ( Weece and Allen, 2010 ). Several researchers have thoroughly investigated the impedance of the mastoid, and the results showed that the mastoid impedance was influenced by age ( Flottorp and Solberg, 1976 ; Zhang, 1994 ; Mackey et al, 2016 ; Nie et al, 2022 )), and that differences in mastoid impedance will lead to differences in the output force of the BC transducer. In addition, there are some differences in mastoid impedance between Chinese subjects and B&K 4930 artificial mastoid ( Nie et al, 2022 ).…”

Section: Resultsmentioning

confidence: 99%

An objective bone conduction verification tool using a piezoelectric thin-film force transducer

Nie

Sang²,

Zheng³

et al. 2022

Front. Neurosci.

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All hearing aid fittings should be validated with appropriate outcome measurements, whereas there is a lack of well-designed objective verification methods for bone conduction (BC) hearing aids, compared to the real-ear measurement for air conduction hearing aids. This study aims to develop a new objective verification method for BC hearing aids by placing a piezoelectric thin-film force transducer between the BC transducer and the stimulation position. The newly proposed method was compared with the ear canal method and the artificial mastoid method through audibility estimation. The audibility estimation adopted the responses from the transducers that correspond to the individual BC hearing thresholds and three different input levels of pink noise. Twenty hearing-impaired (HI) subjects without prior experience with hearing aids were recruited for this study. The measurement and analysis results showed that the force transducer and ear canal methods almost yielded consistent results, while the artificial mastoid method exhibited significant differences from these two methods. The proposed force transducer method showed a lower noise level and was less affected by the sound field signal when compared with other methods. This indicates that it is promising to utilize a piezoelectric thin-film force transducer as an in-situ objective measurement method of BC stimulation.

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“…The physical properties that may explain the different IAA across frequencies were elucidated in the fundamental study by Mackey et al (2016). The authors measured the magnitude of mechanical impedance to vibratile force transduced by a bone conduction hearing device placed on the mastoid or forehead of infants, children, and adults across frequencies of 100 to 10,000 Hz.…”

Section: Effect Of Frequencymentioning

confidence: 99%

“…The resonance frequency is characterized by the point of lowest impedance across the frequencies and a zero-phase delay. Mackey et al (2016) showed that infants had significantly lower impedance in the lower frequencies when compared with adults. In the higher frequencies, infants had higher impedance when compared with adults.…”

Section: Effect Of Frequencymentioning

confidence: 99%

Assessment of Interaural Attenuation in Infants and Young Children Using Bone-Conducted Auditory Brainstem Response

Kariv,

Taitelbaum-Swead,

Levit

2024

Ear &Amp; Hearing

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Objectives: In hearing assessment, the term interaural attenuation (IAA) is used to quantify the reduction in test signal intensity as it crosses from the side of the test ear to the nontest ear. In the auditory brainstem response (ABR) testing of infants and young children, the size of the IAA of bone-conducted (BC) stimuli is essential for the appropriate use of masking, which is needed for the accurate measurement of BC ABR thresholds. This study aimed to assess the IAA for BC ABR testing using 0.5 to 4 kHz narrowband (NB) CE-chirp LS stimuli in infants and toddlers with normal hearing from birth to three years of age and to examine the effects of age and frequency on IAA. Design: A total of 55 infants and toddlers with normal hearing participated in the study. They were categorized into three age groups: the young group (n = 31, infants from birth to 3 mo), middle-aged group (n = 13, infants aged 3–12 mo), and older group (n = 11, toddlers aged 12–36 mo). The participants underwent BC ABR threshold measurements for NB CE-chirp LS stimuli at 0.5 to 4 kHz. For each participant, one ear was randomly defined as the “test ear” and the other as the “nontest ear.” BC ABR thresholds were measured under two conditions. In both conditions, traces were recorded from the channel ipsilateral to the test ear, whereas masking was delivered to the nontest ear. In condition A, the bone oscillator was placed on the mastoid of the test ear, whereas in condition B, the bone oscillator was placed on the mastoid contralateral to the test ear. The difference between the thresholds obtained under conditions A and B was calculated to assess IAA. Results: The means of IAA (and range) in the young age group for the frequencies 0.5, 1, 2, and 4 kHz were 5.38 (0–15) dB, 11.67 (0–30) dB, 21.15 (10–40) dB, and 23.53 (15–35) dB, respectively. Significant effects were observed for both age and frequency on BC IAA. BC IAA levels decreased with age from birth to 36 mo. In all age groups, smaller values were observed at lower frequencies and increased values were observed at higher frequencies. Conclusions: BC IAA levels were both age and frequency dependent. The study found that the BC IAA values for lower stimulus frequencies were smaller than previously assumed, even in infants younger than 3 mo. These results suggest that masking should be applied in BC ABR threshold assessments for NB CE-chirp LS stimuli at 0.5, 1, and 2 kHz, even in young infants. Masking may not be necessary for testing at 4 kHz if a clear response is obtained at 15 dB normal-hearing level (nHL) in infants younger than 3 mo.

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Maturation of Mechanical Impedance of the Skin-Covered Skull: Implications for Soft Band Bone-Anchored Hearing Systems Fitted in Infants and Young Children

Cited by 10 publications

References 40 publications

Hearing Through Bone Conduction Headsets

Hearing Through Bone Conduction Headsets

An objective bone conduction verification tool using a piezoelectric thin-film force transducer

Assessment of Interaural Attenuation in Infants and Young Children Using Bone-Conducted Auditory Brainstem Response

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