Methods and apparatus to communicate via a welding arc are disclosed. An example welding-type power supply includes a power converter, a weld monitor, and an arc modulator. The power converter outputs welding power to sustain a welding-type arc at a welding-type torch. The weld monitor monitors one or more aspects of a weld performed using the welding-type arc and the welding-type torch, and selects an audio message based on the one or more aspects. The arc modulator configured to modify the welding-type arc to output the selected audio message as a plasma speaker.