[Influence of directional microphones on listening effort in middle ear implant users]

Besides speech intelligibility, subjective listening effort is an important outcome for the success of hearing devices and their signal processing. The aim of the present study was to determine subjective listening effort for speech in a noisy background in patients with the active middle ear implant Vibrant Soundbridge (VSB) for omnidirectional and directional microphone settings, with and without occlusion of the contralateral ear.

A total of 15 patients using a VSB were measured using the adaptive categorical listening effort scaling (ACALES) method in a ring of loudspeakers placed in an anechoic room. Different background noises from different directions and simultaneously presented sentences from the Oldenburg sentence test were combined in four different realistic acoustic scenes.

The directional microphone program reduced median subjective listening effort only numerically compared to the omnidirectional microphone program in acoustic scenarios with diffuse noise and with low signal-to-noise ratios; however, this difference failed to reach statistical significance. When occluding the ear contralateral to the VSB, all investigated listening effort categories were measured at significantly higher signal-to-noise ratios than with access to both ears.

Due to missing statistical significance in reduction of listening effort, this study delivered no recommendation for or against usage of the directional microphone program; however, reduced listening effort was shown for binaural listening in comparison to monaural listening. Therefore, patients should be encouraged to always listen with both ears for best results.