 |
| |||
| low frequency sound | |||
| all-bottom sound | |||
| 低频声: 41 phrases in 15 subjects |
| Air defense | 1 |
| Automobiles | 2 |
| Aviation | 3 |
| Earth sciences | 2 |
| Electric machinery | 1 |
| Electronics | 4 |
| Fishery fishing industry | 1 |
| General | 4 |
| Geophysics | 2 |
| Life sciences | 1 |
| Metallurgy | 1 |
| Oil / petroleum | 2 |
| Otorhinolaryngology | 1 |
| Space | 6 |
| Technology | 10 |