Effect of humming frequency on nitric oxide output (nL·min−1) using sinuses with different resonance frequency in the model
| Humming frequency | Sinus resonance frequency | |
| 120 Hz | 200 Hz | |
| 120 Hz | 1043±10 | 527±5.8 |
| 200 Hz | 561±8.3 | 611±7.7 |
| 400 Hz | 286±6.3 | 418±8.1 |