The effect of bimodal auditory stimulation on localization and speech understanding in noise

Abstract Background Hearing loss necessitates technologies like hearing aids and cochlear implants, with cochlear implants proving particularly effective for severe or profound sensorineural cases. Bimodal stimulation, combining cochlear implants with hearing aids, offers promise in improving speech understanding and sound localization in individuals with hearing impairment. Methods This study aims to investigate the effects of bimodal stimulation on auditory perception abilities and sound localization, as well as to compare the auditory skill differences when a hearing aid is used in conjunction with a cochlear implant. The study included twenty participants with bilateral severe to profound sensorineural hearing loss. Depending on the test conditions administered, participants utilized either a unilateral cochlear implant or bimodal stimulation. Patient localization skills were assessed through speakers arranged at 45-degree angles in 8 different directions, and their speech performance in both noisy and quiet environments was evaluated using the Turkish matrix test. Results The data indicated that the use of bimodal stimulation resulted in a statistically significant improvement in pure tone averages and free-field sound localization compared to the unilateral cochlear implant condition ( p < 0.001). Moreover, signal-to-noise ratio (SNR) values acquired from adaptive matrix test assessments in silence and in noise demonstrated that bimodal stimulation offers a statistically significant benefit over unilateral cochlear implants ( p < 0.05). Conclusion The findings of our research revealed that bimodal stimulation enhances voice localization skills in participants. Furthermore, it is determined that bimodal stimulation contributes to improved speech performance by enhancing SNR.