Why Early Tactile Speech Aids May Have Failed: No Perceptual Integration of Tactile and Auditory Signals

Effects of continuous tactile stimulation on auditory-evoked cortical responses depend on the audio-tactile phase

Auditory perception can benefit from stimuli in non-auditory sensory modalities, as for example in lip-reading. Compared with such visual influences, tactile influences are still poorly understood. It has been shown that single tactile pulses can enhance the perception of auditory stimuli depending on their relative timing, but whether and how such brief auditory enhancements can be stretched in time with more sustained, phase-specific periodic tactile stimulation is still unclear. To address this question, we presented tactile stimulation that fluctuated coherently and continuously at 4Hz with an auditory noise (either in-phase or anti-phase) and assessed its effect on the cortical processing and perception of an auditory signal embedded in that noise. Scalp-electroencephalography recordings revealed an enhancing effect of in-phase tactile stimulation on cortical responses phase-locked to the noise and a suppressive effect of anti-phase tactile stimulation on responses evoked by the auditory signal. Although these effects appeared to follow well-known principles of multisensory integration of discrete audio-tactile events, they were not accompanied by corresponding effects on behavioral measures of auditory signal perception. Our results indicate that continuous periodic tactile stimulation can enhance cortical processing of acoustically-induced fluctuations and mask cortical responses to an ongoing auditory signal. They further suggest that such sustained cortical effects can be insufficient for inducing sustained bottom-up auditory benefits.

Bridging a sensory gap between deaf and hearing people–A plea for a situated design approach to sensory augmentation

Deaf and hearing people can encounter challenges when communicating with one another in everyday situations. Although problems in verbal communication are often seen as the main cause, such challenges may also result from sensory differences between deaf and hearing people and their impact on individual understandings of the world. That is, challenges arising from a sensory gap. Proposals for innovative communication technologies to address this have been met with criticism by the deaf community. They are mostly designed to enhance deaf people's understanding of the verbal cues that hearing people rely on, but omit many critical sensory signals that deaf people rely on to understand (others in) their environment and to which hearing people are not tuned to. In this perspective paper, sensory augmentation, i.e., technologically extending people's sensory capabilities, is put forward as a way to bridge this sensory gap: (1) by tuning to the signals deaf people rely on more strongly but are commonly missed by hearing people, and vice versa, and (2) by sensory augmentations that enable deaf and hearing people to sense signals that neither person is able to normally sense. Usability and user-acceptance challenges, however, lie ahead of realizing the alleged potential of sensory augmentation for bridging the sensory gap between deaf and hearing people. Addressing these requires a novel approach to how such technologies are designed. We contend this requires a situated design approach.

FeelMusic: Enriching Our Emotive Experience of Music through Audio-Tactile Mappings

We present and evaluate the concept of FeelMusic and evaluate an implementation of it. It is an augmentation of music through the haptic translation of core musical elements. Music and touch are intrinsic modes of affective communication that are physically sensed. By projecting musical features such as rhythm and melody into the haptic domain, we can explore and enrich this embodied sensation; hence, we investigated audio-tactile mappings that successfully render emotive qualities. We began by investigating the affective qualities of vibrotactile stimuli through a psychophysical study with 20 participants using the circumplex model of affect. We found positive correlations between vibration frequency and arousal across participants, but correlations with valence were specific to the individual. We then developed novel FeelMusic mappings by translating key features of music samples and implementing them with “Pump-and-Vibe”, a wearable interface utilising fluidic actuation and vibration to generate dynamic haptic sensations. We conducted a preliminary investigation to evaluate the FeelMusic mappings by gathering 20 participants’ responses to the musical, tactile and combined stimuli, using valence ratings and descriptive words from Hevner’s adjective circle to measure affect. These mappings, and new tactile compositions, validated that FeelMusic interfaces have the potential to enrich musical experiences and be a means of affective communication in their own right. FeelMusic is a tangible realisation of the expression “feel the music”, enriching our musical experiences.