Influence of transducer types on bone conduction hearing thresholds

Abstract

ObjectiveDifferent types of bone conduction transducers with different physical and electro-acoustic properties are available for audiometric hearing threshold measurements. The reference equivalent threshold vibratory force levels (RETVFL) specified in ISO 389–3 are based on measurements conducted with the B71 and KH70 transducers but apply to all types of transducers available for bone conduction audiometry. The objective of this study was to compare bone conduction hearing thresholds measured by different transducers.DesignIn a prospective study the hearing thresholds were measured psychometrically between 125 Hz and 8000 Hz using the Radioear B71, B81 and Präcitronic KH70 transducers.Study sampleTwenty-one normal hearing participants and fifteen hearing impaired participants.ResultsIn both groups significant differences were found between the thresholds measured with the different transducers at the low frequencies 125 Hz and 250 Hz and the high frequencies 3000 Hz, 4000 Hz, 6000 Hz and 8000 Hz. In the normal hearing group, deviations from the reference threshold 0 dB HL towards lower thresholds were observed for the B71 and B81 at 125 Hz and at the high frequencies 3000 Hz, 4000 Hz, 6000 Hz and 8000 Hz.ConclusionsRETVFL-values should be reassessed and provided specifically for the different transducers.

Air-Conduction and Bone-Conduction Reference Threshold Levels – A Multicenter Study

“…In a study performed at Cambridge (U.K.) University, listeners with SNHL exhibited air-bone gaps at 4000 Hz averaging 19.3 dB when tested with AMTAS (Automated Method for Testing Auditory Sensitivity) and 13.2 dB when tested with conventional manual pure-tone audiometry (Margolis et al 2010). The finding was replicated in follow-up studies using both manual and automated audiometry performed in the U.S. (Margolis et al, 2013), Germany (Fröhlich et al 2018), India (Vijayasarathy and Shetty 2023), and Australia (Eikelboom and Swanepoel, unpublished, data presented in Margolis et al, 2013 ). These false air-bone gaps result from incorrect reference equivalent threshold force levels (RETFLs) for highfrequency (>2000 Hz) stimuli in the International and American audiometer standards (ISO 389-3-2016;ANSI S3.6-2018).…”

Improved Low-Frequency Crosstalk Cancellation in Bone Conduction Using Bone Transducers and Probe Microphone

“…Before starting the experiments, the frequency responses of the two B81 BTs we used in this study were first measured to ensure they had the same response. The measurement set-up used to obtain the B81 frequency response was adopted from Jansson, Frohlich, et al [28], [29]. The B81 BT was applied to a B&K 4930 artificial mastoid with a static force of 5.4 N, as illustrated in Fig.…”

Unilateral crosstalk cancellation via bone conduction: Methods and evaluation

“…Note that the choice of signal for measuring impulse responses may depend on whether the transducer exhibits nonlinear behaviour. In our experiments, the TSP signal was appropriate given its compatibility with the B81 audiometric bone transducer, which is characterized by its low harmonic distortions [26] . Conversely, when using the B71 transducer, which is known for its pronounced harmonic distortions [26] , exponential sweeps [ 25 , 27 ] could be a more fitting choice to account for these distortions.…”