A sound wave travels from a glass panel into glycerol. Measurements are shown in the table.
| Medium | Speed of sound (m/s\mathrm{m/s}m/s) | Wavelength (m\mathrm{m}m) |
|---|---|---|
| Glass panel | 4500 | — |
| Glycerol | 1900 | 7.6 |
Which option gives the class of the wave and its wavelength in the glass panel?
audible sound, 18 m18\ \mathrm{m}18 m
infrasound, 7.6 m7.6\ \mathrm{m}7.6 m
infrasound, 18 m18\ \mathrm{m}18 m
audible sound, 3.2 m3.2\ \mathrm{m}3.2 m