A Randomized Crossover Study in Single-Sided Deafness Comparing a Cartilage Conduction CROS System and an Air-Conduction CROS System

Abstract

Objective: To investigate if cartilage conduction (CC) rerouting devices are noninferior to air-conduction (AC) rerouting devices for single-sided deafness (SSD) patients by measuring objective and subjective performance using speech-in-noise tests that resemble a realistic hearing environment, sound localization tests, and standardized questionnaires.

Study design: Prospective, single-subject randomized, crossover study.

Setting: Anechoic room inside a university.

Patients: Nine adults between 21 and 58 years of age with severe or profound unilateral sensorineural hearing loss.

Interventions: Patients' baseline hearing was assessed; they then used both the cartilage conduction contralateral routing of signals device (CC-CROS) and an air-conduction CROS hearing aid (AC-CROS). Patients wore each device for 2 weeks in a randomly assigned order.

Main outcome measures: Three main outcome measures were 1) speech-in-noise tests, measuring speech reception thresholds; 2) proportion of correct sound localization responses; and 3) scores on the questionnaires, "Abbreviated Profile of Hearing Aid Benefit" (APHAB) and "Speech, Spatial, and Qualities of Hearing Scale" with 12 questions (SSQ-12).

Results: Speech reception threshold improved significantly when noise was ambient, and speech was presented from the front or the poor-ear side with both CC-CROS and AC-CROS. When speech was delivered from the better-ear side, AC-CROS significantly improved performance, whereas CC-CROS had no significant effect. Both devices mainly worsened sound localization, whereas the APHAB and SSQ-12 scores showed benefits.

Conclusion: CC-CROS has noninferior hearing-in-noise performance except when the speech was presented to the better ear under ambient noise. Subjective measures showed that the patients realized the effectiveness of both devices.