An inexpensive alternative for recording middle ear muscle activity (MEMA) during sleep.

In past studies of middle ear muscle activity (MEMA) in sleep, one of two methods of recording has been used: an acoustic impedance bridge (AIB) or a miniaturized pressure transducer (MPT). A low-cost and less fragile piezoresistive pressure transducer was tested to determine its practicality in recording MEMA during sleep in humans. A specialized ear mold accommodating both types of pressure transducer was custom-fitted for six subjects. The sleep of each subject was analyzed epoch by epoch for one night to determine comparability of the two transducers. In no case did either transducer indicate a MEMA without confirmation by the other. It is recommended that this type of transducer would be practical for researchers interested in recording MEMA in sleep.

Middle-ear muscle activity (MEMA) and its association with motor activity in the extremities and head in sleep.

Middle-ear muscle activity (MEMA) in sleep was simultaneously recorded from both ears using extratympanic manometry. Head movement, speech movements, ankle flexion and wrist movement were monitored by electromyographic recording using surface electrodes at the back of the neck, second laryngeal notch, anterior tibialis and forearm muscle. Motor events recorded from these electrode placements were examined for correlation with MEMA to test the hypothesis that the middle-ear muscles are activated in conjunction with other motor activities, aside from eye movements, by a central motor command system. Phi coefficients were calculated for each subject; all were positive, thus indicating an association between MEMA and other noneye movement motor events. These results suggest that there is a central phasic motor system responsible for MEMA and associated phasic motor activity in sleep.

A sensitive air pressure-measuring transducer for indirect middle ear muscle recording in humans.

In the past, the recording of middle ear muscle activity (MEMA) during sleep was accomplished with the use of the acoustic impedance bridge (AIB). However, two major concerns with this technique are: 1. augmentation of MEMA (and possible impairment of the auditory apparatus), as a consequence of the 85-95 dB probe tone, which is necessary for acoustic tympanometry; 2. the AIB recording method is susceptible to snoring artifact so that determination of true MEMA events is difficult. By utilizing a highly sensitive air-pressure measuring transducer (AMPT), we were able to record MEMA accurately without artifactual stimulation of this endogenously occurring REM sleep phasic activity. Possible damage to inner ear structures is precluded because no sound input is required with the AMPT.