https://freesound.org/people/InspectorJ/sounds/395441/

1. a wobbly sine wave, compared to a regular sound wave this sound modulates its frequency clearly
2. sonic visualiser analysis, drags the frequency, I dont know how to or if its possible to remove the source sound to leave just the effect, the frequencies are very spread out but remain in the higher range
3. –
4. vibrato, other examples:

https://freesound.org/people/Carlos_Vaquero/sounds/153883/ double bass

https://freesound.org/people/kalhan/sounds/529292/ a birds call containing vibrato