<p>To analyze the effects of cold, sour, and combined cold-sour stimulation on swallowing muscle activity by recording surface electromyographic (sEMG) signals from the masseter, submental, and infrahyoid muscles in healthy individuals, thereby investigating the impact of these sensory stimuli on swallowing function. Thirty healthy participants (15 males, 15 females) were recruited. Participants maintained an upright seated position with the head neutrally aligned. They received 15 mL injections of room-temperature water, cold water, sour water, and cold-sour water via needle-free syringe in sequence. Each liquid was tested three times under two protocols: single-swallow stimulation (immediate swallowing) and 5-s sustained stimulation (holding liquid for 5 s before swallowing). To mitigate fatigue, a 30-s rest interval was enforced between trials. Bilateral sEMG signals from target muscles were recorded for root mean square (RMS) and mean power frequency (MPF) analysis. Single-swallow stimulation: Sour stimulation significantly increased RMS in bilateral submental muscles (<i>P</i> &lt; 0.05), whereas cold-sour stimulation elevated RMS in the right submental muscle (<i>P</i> &lt; 0.05). Both sour and cold-sour stimulation reduced MPF in bilateral masseter muscles (<i>P</i> &lt; 0.0083). 5-s sustained stimulation: Sour stimulation activated RMS in bilateral masseter and left submental muscles (<i>P</i> &lt; 0.05), while sour and cold-sour stimulation enhanced RMS in bilateral submental muscles (<i>P</i> &lt; 0.0083) and decreased MPF in bilateral masseter (<i>P</i> &lt; 0.05) and left submental muscles (<i>P</i> &lt; 0.05). Compared to cold stimulation, sour stimulation more effectively activates the masseter and submental muscles, and prolonging stimulation duration enhances efficacy.</p>