Devices and methods for arc fault detection, based on arc sound signals, are disclosed. The device can monitor sound data from a power device by one or more microphones arranged near the power device and extract the characteristic of the sound data. The device can also compare the characteristic of the sound data with the arc fault feature database, and then determine to generate an arc alarm signal. The device is a stand-alone device, which can provide the forecast and early warning of arc faults, and can improve the reliability of arc fault detection.