The Effect of Dual-target tACS Combined With Speech Training on Repetition Disorder After Stroke

This clinical trial aims to study whether dual-target transcranial alternating current stimulation (tACS) applied to the auditory and motor brain region can improve repetition disorder in people with stroke, and to evaluate the safety of tACS. The main goals are to answer the following questions: 1. Can dual-tACS stimulation of the auditory and motor brain area improve repetition functions in people with aphasia after stroke? 2. Can it improve the integration of auditory information and speech motor control during communication? Researchers will compare the effects of real tACS versus sham (placebo) stimulation to see if real stimulation leads to better outcomes in aphasia patients. Participants will: 1. Receive one extra 20-minute session of either real or sham tACS each day for 10 days 2. Attend clinic visits before and after 10-days stimulation for clinical assessments(WAB) and fNIRS recording related brain activity