The input impedance of the FE185 Neuro Amp EX and Headstage is very high (compared to other commercial amplifiers, which often have lower input impedances). This ensures an optimal noise/signal ratio and minimizes the need for external shielding.
When trying to listen to nerve sounds it is recommended that the user first identify the location of the nerve using extraneural and intraneural electrical stimulation.
Using electrical stimulation to first identify the nerve is preferable to simply using auditory sounds to find it. The latter relies on random identification, whilst electrical stimulation ensures accurate electrode placement.
While it is possible to use high quality speakers (with Bass and Treble equalization options), when the Neuro Amp EX is recording from electrodes placed close to the nerve fascicle, auditory signals can be obtained from the audio output of the amplifier using standard PC speakers.