This study aimed to compare the sound pressure levels (SPL) generated by four different ventilator models operating in high-flow nasal cannula (HFNC) mode during HFNC therapy. Although HFNC therapy is widely used for respiratory support, the acoustic characteristics of the HFNC mode in ventilators remain largely unexplored. Four ventilators were investigated: Vivo3, EO-150, LUISA, and prismaVENT50-C. SPL were measured using a digital sound level meter positioned 1 m from each ventilator operating at flow rates of 30, 40, 50, and 60 L/min. At the low flow range (30-40 L/min), all ventilators exhibited similar SPL of 32.6-35.0 A-weighted decibels [dB(A)]. However, a marked difference was observed at high flow rates; the Vivo3 demonstrated a substantial increase to over 50 dB(A) at flow rates exceeding 40 L/min, whereas the other three ventilators maintained gradual increases, reaching only 38.8-40.4 dB(A) at maximum flow. Analysis of SPL change rates across different flow ranges revealed that the Vivo3 exhibited a dramatic rate of 1.69 dB/L/min in the 40-50 L/min range; this rate was approximately 6 to 8 times higher than those observed in the other ventilators. The notable variation in acoustic generation among the ventilators, particularly at high flow rates, highlights the importance of considering SPL characteristics when selecting devices for clinical use. At high flow rates, the Vivo3 generated SPL exceeding the recommended SPL limits for healthcare settings, which may potentially impact patient outcomes, including sleep quality and recovery.