Bone Conduction Trial Device to Eliminate the Effect of Transcranial Attenuation: A Prospective Observational Study in Single-Sided Deaf Subjects

OBJECTIVES: The contact miniTM (CM) is a nonimplantable, digital bone conduction device (BCD) consisting of 2 isolated units: an electronic housing, including the microphone, and a vibrator housing. The study investigated whether the CM can be used as an alternative test device for a BCD trial in single-sided deaf (SSD) adults with the microphone placed at the SSD ear and the vibrator at the normal-hearing (NH) ear (i.e., cross position). METHODS: Twenty SSD adults (mean age: 50 [±13.2] years) participated in a 2-week BCD trial with the CM on the headband in cross position. Prior to the trial, the subjects performed adaptive speech-in-noise tests in an unaided condition. After the trial, speech-in-noise tests were performed with the CM in cross position (CMcross) and ipsilateral position, i.e., both units at the SSD ear (CMipsi). Five different speech-in-noise configurations were used (S0N0; S0NNH; S0NSSD; S0°NNH+SSD; and SSSDNNH). Speech reception thresholds (SRT) were analyzed comparing the unaided, the CMcross condition, and the CMipsi condition. RESULTS: Friedman's test revealed no significant differences in SRTs between the CMcross, CMipsi, and the unaided condition for the S0N0, S0NNH, S0NSSD, and S0°NNH+SSD configuration. However, in the SSSDNNH configuration, a significant effect was found (p < 0.001). Wilcoxon pairwise comparisons with Bonferroni correction indicated that SRTs in the CMcross condition were significantly lower (i.e., better speech understanding) than those in the unaided (p < 0.001) and the CMipsi condition (p < 0.05). CONCLUSION: The CM may be a good alternative for patients with SSD, resulting in significantly better speech recognition when noise is presented to the NH ear and speech to the SSD ear. As the speech recognition results are better in the cross than the ipsilateral position, the CMcross might help to overcome the negative effect of transcranial attenuation during BCD trials.