pitch envelope

is there one in audacity?
if not, is there a way to achieve the same effect?

There is a “Time Track” feature that may do what you want: http://manual.audacityteam.org/o/man/time_tracks.html

it did what i wanted, but i was wondering if i could make the time track affect only one track, not everything in my mix.

Yes you can, sort of :wink:

You would need to create the time track envelope (this will affect all tracks), then:
Select the track that you want it to affect.
Tracks menu > Mix and Render. This will “render” the selected track and in so doing will “apply” the time envelope to the track. The selected track(s) are “used up” (disappear) and a new “Mix” track is created at the bottom (below all other non-selected tracks).
Then delete the Time Track (click on the [X] in the top left corner of the track.

See here about “Mix and Render”: http://manual.audacityteam.org/o/man/tracks_menu.html#mix