Measurements of bone conduction auditory brainstem response with the new audiometric bone conduction transducer Radioear B81^*

Figures & data

Figure 1. Mean and individual ABR Wave V amplitude (A) and latency (B) values obtained for tone bursts of 500 Hz, 2000 Hz, 4000 Hz, click and broad-band chirp stimuli by the B71 (triangles) and the B81 (circles). The data of the BC transducers are shown side by side for each stimuli level and the scatter plot shows individual values. Error bars represent 95% confidence intervals for the mean values. For the latency data (B), Wave V latency in response to broad-band chirp stimuli were adjusted by the Eclipse system to allow direct comparison with clicks (TB: tone burst).

Figure 2. Boxplot of the observed differences in ABR wave V amplitudes calculated as percentage difference (see Methods section) for the B81 across the stimuli used. The lines mark the medians, the boxes extend from the 25th to 75th percentiles, and the whiskers extend from 10th to 90th percentiles. Symbols mark the outliers. (TB: tone burst).

Table 1. Summary of the comparison of the ABR wave V amplitudes obtained by the B71 and the B81 for each sound stimulus and intensity level.

Intensity	Mean Difference (μV)^a	MDD (μV)^b
500 Hz tone burst
20 dB nHL	0.025	0.070
50 dB nHL	0.021	0.073
2000 Hz tone burst
20 dB nHL	−0.007	0.039
50 dB nHL	−0.011	0.045
4000 Hz tone burst
20 dB nHL	−0.034	0.053
50 dB nHL	−0.037	0.073
Click
20 dB nHL	−0.040	0.097
50 dB nHL	0.040	0.078
Broad-band chirp
20 dB nHL	0.007	0.078
50 dB nHL	0.023	0.093

^aObserved difference in wave V amplitude.

^b Minimal detectable difference (MDD) values estimated by power analysis of the data for a significance level of 0.05 and a power of 0.8.

Figure 3. The amplitude of the electrical stimulus artefact imposed on the ABR recordings for the B71 (triangles) and the B81 (circles). Mean of the peak values of Hilbert envelopes of single polarity sweeps are given side by side for the two BC transducers. Scatterplot shows the individual values. Only the sweeps recorded in response to 50 dB nHL stimulus level were analysed. Error bars represent 95% confidence intervals of the mean values. Arrow indicates an outlier with a value of 43.75 µV. Inset shows a sample trace recorded using the B71 and 4000 Hz tone burst stimulus. Hilbert envelope of the electrical artefact caused by the BC transducer is marked by the letter H. Asterix marks the wave V ABR response.

Table 2. Summary of stimulus parameters utilised in previous bone conduction ABR studies on normal hearing adults using the B71.

Stimulus parameters	Rate (Hz)
Tone burst frequencies (duration), gating
Gorga et al. (1993)
250, 500, 1000, 2000, 4000 Hz (4, 6, 4, 3, 2 msec), Blackman	37
Small and Stapells (2003)
500, 1000, 2000, 4000 Hz (2-1-2 cycle), linear	10
Current study
500, 2000, 4000 Hz (5-cycle), Blackman	37.2
Click duration
Beattie (1998)
100 μs rectangular pulse	33.1
Current study
100 μs rectangular pulse	37.2
Broadband chirp type
Cobb and Stuart (2016)
CE-Chirp	57.7
Current study
CE-Chirp LS	37.2

Table 3. Summary of ABR Wave V latency values in normal hearing adults reported in previous studies using the B71.

	Mean wave V latency (ms)
	Current study	Gorga et al. (1993)^a	Beattie (1998)	Cobb and Stuart (2016)
	Stimulus Intensity (dB nHL)
	20/50	20/50	20/40	30
Tone bursts
500 Hz	14.9/11.7	12.5/10^b
2000 Hz	9.9/8	10/8
4000 Hz	8.8/6.9	9/7.5
Click	8.2/6.7	9/7.5	8.02/7.31
Broadband chirp	8.2/6.7			8.88^c

^aApproximate values estimated from figures.

^b Value obtained for 40 dB nHL.

^c CE-Chirp, which is the earlier version of the level-specific CE-chirp LS.

Gorga, M. P., J. R. Kaminski, K. L. Beauchaine, and B. M. Bergman. 1993. “A Comparison of Auditory Brain Stem Response Thresholds and Latencies Elicited by Air- and Bone-Conducted Stimuli.” Ear Hear 14 (2): 85–94. doi:10.1097/00003446-199304000-00003.

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Small, S. A., and D. R. Stapells. 2003. “Normal Brief-Tone Bone-Conduction Behavioral Thresholds Using the B-71 Transducer: three Occlusion Conditions.” Journal of the American Academy of Audiology 14 (10): 556–562. doi:10.3766/jaaa.14.10.4.

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Beattie, R. C. 1998. “Normative Wave V Latency-Intensity Functions Using the EARTONE 3A Insert Earphone and the Radioear B-71 Bone Vibrator.” Scandinavian Audiology 27 (2): 120–126. doi:10.1080/010503998420360.

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Cobb, K. M., and A. Stuart. 2016. “Auditory Brainstem Response Thresholds to Air- and Bone-Conducted CE-Chirps in Neonates and Adults.” Journal of Speech, Language, and Hearing Research 59 (4): 853–859. doi:10.1044/2016_JSLHR-H-15-0182.

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