An Exploratory Study of Bimodal Electro-Aural Stimulation Through the Ear Canals for Tinnitus.

Objective: The aim of this study was to explore the potential for bimodal auditory and noninvasive electrical stimulation at the ears to alleviate tonal, somatic tinnitus that was investigated in a small preliminary trial (11 participants).

Design: Auditory stimulation took the form of short "notched noise" bursts customized to each participant's tinnitus percept. Simultaneous pulsed electrical stimulation, intended to facilitate neuroplasticity, was delivered via hydrogel electrodes placed in opposite ears.

Binaural sensitivity as a function of interaural electrode position with a bilateral cochlear implant user.

Experiments were conducted with a single, bilateral cochlear implant user to examine interaural level and time-delay cues that putatively underlie the design and efficacy of bilateral implant systems. The subject's two implants were of different types but custom equipment allowed presentation of controlled bilateral stimuli, particularly those with specified interaural time difference (ITD) and interaural level difference (ILD) cues. A lateralization task was used to measure the effect of these cues on the perceived location of the sensations elicited.

Evaluation of response methods for the localization of nearby objects.

Four response methods for indicating the perceived locations of nearby objects were evaluated: the direct-location (DL) method, where a response pointer is moved directly to the perceived location of the target; the large-head (LH) and small-head (SH) methods, where the pointer is moved to the target location relative to a full-scale or half-scale manikin head; and the verbal report (VR) method, where the spherical coordinates of the target location are indicated verbally. Measurements with a visual target indicated that the DL method was relatively unbiased and considerably more accurate than the other methods, which were all roughly equivalent. Correcting for bias improved accuracy in the LH, SH, and VR responses, but not to the level of the uncorrected DL responses.

Auditory localization of nearby sources. II. Localization of a broadband source.

Although many researchers have examined auditory localization for relatively distant sound sources, little is known about the spatial perception of nearby sources. In the region within 1 m of a listener's head, defined as the "proximal region," the interaural level difference increases dramatically as the source approaches the head, while the interaural time delay is roughly independent of distance. An experiment has been performed to evaluate proximal-region localization performance.

Information transmission with a multifinger tactual display.

In this work, the tactual information transmission capabilities of a tactual display designed to provide stimulation along a continuum from kinesthetic movements to cutaneous vibrations are assessed. The display is capable of delivering arbitrary waveforms to three digits (thumb, index, and middle finger) within an amplitude range from absolute detection threshold to about 50 dB sensation level and a frequency range from dc to above 300 Hz. Stimulus sets were designed at each of three signal durations (125, 250, and 500 msec) by combining salient attributes, such as frequency (further divided into low, middle, and high regions), amplitude, direction of motion, and finger location.