hi. i have a question that is not directly related to houdini but more about the process of making an animation.

how are sounds created for an animation. suppose we have a scene in which a truck passes. are the sounds recorded or created using a computer software?

mostly sound design on a pc and some time recordet

Take a look at http://audacity.sourceforge.net/ [audacity.sourceforge.net]. If you are like me you will also soon take a look at commercial sound effects libraries It's really an art-form in itself.

that should be really interesting to make the sound of a truck by pc. are there tutorials on doing such things?

can chops do this thing?

and a lot of fun to do sound design score etc

Most film sound effects are derived from recorded material, which are then arranged in time layered on top of other sounds (such as ambience, music etc.) using multi-tracker software. Steinberg Nuendo has strong audio to video features (and is very expensive), while Cockos Reaper has good audio capabilities, but limited video features (and is very cheap).

Check out: - http://filmsound.org/starwars/ [filmsound.org] for some insight into creative sound design. Probably filmsound.org will have lots of other really great things, but the Star Wars thing is the only article I've read on there.
- freesound.org has lots of raw audio materials
- reaper.fm is the homepage of the Reaper audio software. Learning will be required.

Houdini can be used to trigger the playback of sound effects in time with visual events… which is quite cool. Creating sound effects from scratch (procedurally) can be very difficult though. Have a look at http://en.wikipedia.org/wiki/Physical_modelling_synthesis [en.wikipedia.org]

And if you're not scared off by that,
Here's a technical paper on generating footstep sounds:
http://vbn.aau.dk/files/37619504/Turchet_Serafin_Dimitrov_Nordahl_DAFx10_P50.pdf [vbn.aau.dk]

sound design and scoring for movies and games are expensive and a bit of a hassle but yea non the less my main passion

thank you guys. i had no idea designing sound is such a big deal. i'll have a look and see if i can figure sth out. if i did, i would ask for more links.