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Functional magnetic resonance imaging (fMRI) enables sites of brain activation to be localized in human subjects. For auditory system studies, however, the acoustic noise generated by the scanner tends to interfere with the assessments of this activation. Understanding and modeling fMRI acoustic noise is a useful step to its reduction. To study acoustic noise, the MR scanner is modeled as a linear electroacoustical system generating sound pressure signals proportional to the time derivative of the input gradient currents. The transfer function of one MR scanner is determined for two different input specifications: 1) by using the gradient waveform calculated by the scanner software and 2) by using a recording of the gradient current. Up to 4 kHz, the first method is shown as reliable as the second one, and its use is encouraged when direct measurements of gradient currents are not possible. Additionally, the linear order and average damping properties of the gradient coil system are determined by impulse response analysis. Since fMRI is often based on echo planar imaging (EPI) sequences, a useful validation of the transfer function prediction ability can be obtained by calculating the acoustic output for the EPI sequence. We found a predicted sound pressure level (SPL) for the EPI sequence of 104 dB SPL compared to a measured value of 102 dB SPL. As yet, the predicted EPI pressure waveform shows similarity as well as some differences with the directly measured EPI pressure waveform. [ABSTRACT FROM AUTHOR]

A sonar based device with tactile feedback was developed to improve the mobility and independence of visually impaired individuals. It features a transceiver/receiver, a potentiometer, a microcontroller, a rechargeable polymer lithium ion battery, and a Nokia Cell phone vibrator. All components are commercially available and housed in a custom acrylic package with 86 mm × 34 mm × 12 mm in dimension, and 120 grms in weight. Additionally, the device features an adjustable detection scheme for user customization of distance range, and a tactile feedback system that avoids interference with auditory sensory information. The device was tested for its navigational efficacy in an artificial indoor environment, and in a live outdoor setting. Ten subjects (9 males and 1 female), with a mean age of 35 years-old (range: 17 to 52) were presented with a series of navigational tasks resulting in considerable reduction of head, shoulder, chest, and arms collisions during their locomotion. We conclude that this device greatly improves the mobility and safety of visually impaired individuals.

Current research is in agreement with the presence of a magnetic compass in living beings including humans. The two most accepted explanations that demonstrate the existence of magnetoreceptors in living beings are, the radical pair and the biogenic magnetite, which are discussed here with its respective experimental evidence and support. It indicates the presence of magnetite crystals in otoliths, among different inferior species of animals. Moreover, the magnetite found in several organs of human body allows predicting the existence of such element, in otoliths of vestibular system as well; further, anticipates that human magnetoreception is an additional function of the vestibular system. These geomagnetic signals would modulate balance, movement and spatial positioning of man in concordance of gravity values. This new field of otomagnetism opens new research areas for understanding the mechanisms involved in balance, equilibrium, orientation, and space positioning in normal and disease populations. Likewise, this could be the starting point for application of new human neurorehabilitation procedures, in those magnetoreception-associated neurological disorders that happen in the earth, the sea or the air.