Human Research and Engineering Directorate Research Areas

Tactile & Bone Conduction Communication

Advisor: Kalb, Joel (joel.kalb@us.army.mil; 410-278-5977)

Location: Human Research and Engineering Directorate, Aberdeen Proving Ground, MD 21005-5425

Key words: Tactile, Bone Conduction, Communication, Perception, Display, Head, Mounted, Auditory

Tactile displays can provide information to Warfighters when other sensory modalities, such as hearing and vision, are cognitively overloaded. ARL is investigating the use of tactile displays for enhancing communication in adverse military environments, including a head-mounted application. A head-mounted tactile device would intuitively present directional or collective stimulation and would quietly warn or aid in navigation without competing for visual or auditory attention. In addition, current tactile transducers can provide both a tactile and an auditory sensation depending on the excitation frequency used such as from slow (10 Hz) and fast (250 Hz) mechanical stimulation of specialized receptors in the skin. Research may include the optimization of tactile signals, determining the most efficient operation mode (displacement, velocity, acceleration) for tactile transducers, miniaturization of head-mounted tactile devices, and person-to-person communication.

Humans can hear auditory signals through air conduction (the pathway that starts with the external ear) and bone conduction (through vibrations of the skull). Radio and audio signals can be converted into skull vibration by vibrators located on the head, and skull vibrations during speech production can be picked up by bone microphones (accelerometers) and transmitted over audio and radio channels. In quiet environments, ears can be kept open facilitating auditory awareness of the environment while in noisy environments ears can be covered by hearing protectors. In addition, bone conduction transducers can be placed at various locations on the head and hidden under hair making them ideal devices for stealth operations. This research opportunity may involve optimization of bone conduction interfaces, development of distributed and multichannel bone conduction communication systems, and assessment of bone conduction effectiveness under various operational conditions.

Finally, this research topic includes the investigation of the synergistic blend of a tactile-BC communication system. The combined technologies in a usable display will explore the strengths of each, such as in high ambient noise or physical exertion situations, where rich information, such as threat type and location can be presented to the Warfighter in a highly intuitive manner. Equipment (i.e., tactile-BC transducer) and prototype development, the optimization of materials, and means of application are worthy study problems for this portion of research.

Reference:

Mortimer BJ, Zets GA, Cholewiak RW: Journal of the Acoustical Society of America 121: 2970, 2007