Enhancing speech recall and reducing cognitive load through rhythmic amplitude modulated vibrotactile stimulation in noise.

This study introduces and evaluates Rhythmic Amplitude Modulated Vibrational (RAM-Vib) stimulation for improving speech recall and reducing cognitive load in noisy environments. Building on multisensory integration and neural entrainment theories, three experiments tested and refined RAM-Vib for Japanese speech in noise. Initial experiments focused on speech perception and attention using either amplitude-envelope (Exp 1) or speech-rhythm alone (Exp 2). While these approaches reduced cognitive load, they did not improve recall, often due to perceived feedback quality or synchronicity issues. However, Experiment 3, combining both rhythmic patterns with dynamic amplitude modulation (RAM-Vib), yielded significant improvements. This integrated RAM-Vib not only enhanced speech recall but also reduced objective cognitive load (measured through Skin Conductance Level), indicating a more efficient memory resource allocation. These findings demonstrate that RAM-Vib using rhythmic patterns and dynamic amplitude changes synchronized with the speech amplitude guides attention and facilitates multisensory processing. This could be a promising, non-intrusive tool to improve speech recall and reduce cognitive load in noisy or difficult listening situations.