http://cec.sonus.ca/econtact/14_2/stevens_needle.html

A Very Fine Needle is a recording of an electromyography (EMG) [1] test I underwent for Ocular Myasthenia. The test involves a very thin needle being inserted into a muscle to measure its electrical activity. The electrical activity picked up by the electrodes is then displayed on an oscilloscope and an audio-amplifier is used so the activity can be heard, and evaluated, by the consultant. As an artist who works a lot with sound I found it completely fascinating, lying there and hearing my bodies muscle activity amplified by this process.

In enquiring about the method deployed I found out that the needle used here is a recording device. The needle has a silver wire (the active electrode) inside a shaft of metal (which is used as the reference electrode). By placing a ground electrode on the patient, the physician can obtain a very precise measurement, since the active electrode and the reference electrode are very close to each other.