[GRASS-user] noise propagation script

[honza]

Hi everyone,
I'm trying to make script of noise level propagation for grass. I just
stop at this point:
done - map with values of inhibit for every place,(negative values)
     - values of noise in source of noise (vector points, positive
values)
And I would like to use something similar r.cost, but with decreasing
efect. Have you any hint how to solve this problem?
Thanks Honza