Benefit of a Contralateral Routing of Signal Device for Unilateral Cochlear Implant Users

Abstract

Objective: To investigate objective and subjective effects of an adjunctive contralateral routing of signal (CROS) device at the untreated ear in patients with a unilateral cochlear implant (CI). Design: Prospective study of 10 adult experienced unilateral CI users with bilateral severe-to-profound hearing loss. Speech in noise reception (SNR) and sound localization were measured with and without the additional CROS device. SNR was measured by applying speech signals at the untreated/CROS side while noise signals came from the front (S90N0). For S0N90, signal sources were switched. Sound localization was measured in a 12-loudspeaker full circle setup. To evaluate the subjective benefit, patients tried the device for 2 weeks at home, then filled out the abbreviated Speech, Spatial and Qualities of Hearing Scale as well as the Bern benefit in single-sided deafness questionnaires. Results: In the setting S90N0, all patients showed a highly significant SNR improvement when wearing the additional CROS device (mean 6.4 dB, p < 0.001). In the unfavorable setting S0N90, only a minor deterioration of speech understanding was noted (mean -0.66 dB, p = 0.54). Sound localization did not improve substantially with CROS. In the two questionnaires, 12 of 14 items showed an improvement in mean values, but none of them was statistically significant. Conclusion: Patients with unilateral CI benefit from a contralateral CROS device, particularly in a noisy environment, when speech comes from the CROS ear side. © 2014 S. Karger AG, Basel

Application of Wireless Contralateral Routing of Signal Technology in Unilateral Cochlear Implant Users with Bilateral Profound Hearing Loss

“…As expected (Niparko et al, 2003;Lin et al, 2006), the assessment of CROS benefit when speech is in front of the unilateral CI listener (Arora et al, 2013;Grewal et al, 2015) results in marginal benefit compared with those designed to measure head shadow effect (van Loon et al, 2014;Taal et al, 2016). Furthermore, these studies all used hearing aids (Arora et al, 2013;Grewal et al, 2015;Guevara et al, 2015;Weder et al, 2015;Taal et al, 2016) or lapel microphones (van Loon et al, 2014) hard-wired to a CI processor to deliver the contralateral microphone input. Although promising, such systems are not optimized for application in CIs, and variables such as directional microphones were not considered.…”

“…Rerouting of bilateral input for MLs is a promising alternative for patients who cannot benefit from binaural input (Arora et al, 2013;Weder et al, 2015;Taal et al, 2016). Early studies of CROS application in unilateral CI have demonstrated variable results (Arora et al, 2013;van Loon et al, 2014;Grewal et al, 2015;Guevara et al, 2015;Weder et al, 2015). Outcomes were reported in terms of hearing performance in noise.…”

“…SIN measures can be either fixed where a percent correct score is obtained at a fixed signal-to-noise ratio (SNR) level, or adaptive where either the speech or the noise is adjusted to determine an individual's threshold (SNR, where 50% of the presented speech can be identified) for hearing in noise (Taylor, 2003). Studies measuring differences in overall percent correct scores suggested limited benefit (Arora et al, 2013;Grewal et al, 2015;Guevara et al, 2015), whereas studies of speech reception thresholds suggested a positive effect of CROS input to the CI (van Loon et al, 2014;Weder et al, 2015;Taal et al, 2016). Given the variability in speech perception among CI recipients, threshold measures may be more resistant to these inherent variances in the CI population.…”

Contralateral Routing of Signal Yields Significant Speech in Noise Benefit for Unilateral Cochlear Implant Recipients

“…As a result, the net benefit of CROS devices in unilateral CI recipients has been mixed. Whereas some groups have reported that adding the CROS is not detrimental to speech understanding in noise when noise is presented to the CROS ear (Weder et al, 2015) or not significantly different (Wimmer et al, 2017), other work has shown a negative impact on speech understanding (Arora et al, 2013;Van Loon et al, 2014;Grewal et al, 2015;Taal et al, 2016). For speech understanding in quiet, some studies have shown no benefit of CROS (Taal et al, 2016), whereas other studies have demonstrated significant benefit for CROS with unilateral CI recipients (Arora et al, 2013;Grewal et al, 2015;Guevara et al, 2015).…”

Comment on the Paper by Weder et al. Entitled ‘Benefit of a Contralateral Routing of Signal Device for Unilateral Cochlear Implant Users'

“…We would like to formally address the above article [Weder et al, 2015] in which it is mentioned in the Introduction section, paragraph 2, that '… a CROS device has never been studied as an aid to patients with a unilateral CI, a condition which has some similarities to single-sided deafness'.…”