Earspeaker coupling effects on auditory action potential and brainstem responses.

Human auditory nerve action potential and brainstem evoked response input-output functions were obtained with standard audiometric earspeakers coupled in three different ways, commonly used in auditory evoked potential laboratories (ie, free field, circumaural cushions, standard audiometric cushions). All other stimulus values were matched as closely as possible. Under the different coupling conditoins, substantially different amplitude-intensity and latency-intensity functions were generated for both auditory nerve N1 and brainstem V peaks.

Normal short-latency electrophysiological filtered click responses recorded from vertex and external auditory meatus.

We recorded normal electrophysiological responses to third-octave filtered clicks from external auditory meatus (EAM) and vertex electrodes referred to coupled earlobe electrodes (forehead ground). From both vertex and EAM, polarity-sensitive responses predominated at low frequencies and exhibited characteristics of both phase-locked neural responses (frequency-following response or FFR) and cochlear microphonics (CM). The FFR-like response predominated at the vertex site and the CM-like response predominated at EAM.

Pion radiotherapy: studies with nuclear emulsions.

Nuclear emulsions were used to provide information on (1) the pion star distribution for a therapy beam; (2) star production as a function of pion energy and residual range in nuclear emulsion; (3) the distribution of nuclear framgent ranges in emulsion; and (4) the neutron energy spectrum and fluence produced by negative pion capture in tissue, during treatment of a patient. This last item is important for determining the whole-body dose delivered to a patient undergoing pion radiotherapy.