Never place electrodes in a way that forces the electrical current to pass through your heart. Keep all pads and probes on the lower half of the body.
To fully appreciate the value of dedicated electro+stim+audio+files, you need to understand the hardware chain: electro+stim+audio+files
Unlike traditional TENS units that use pre-set, repetitive pulses, an audio-driven e-stim system converts the amplitude (volume), frequency (pitch), and phase relationships of an audio file into real-time electrical waveforms. Never place electrodes in a way that forces
To use audio files for e-stim, you typically need a device with an "audio-in" or "stereo-in" capability: Common Devices E-Stim Systems 2B electro+stim+audio+files
The device reads the frequency and amplitude of the audio signal.