Human Noise Perception

[Eshet]

Hello to all.
i'm interested in the transition from noise spectrum to the level of 
annoyance. I have measured noise spectrum in dBSPL and i want to find out if 
that noise cause damage to whom who listens to it.
i know that there are graphs and tables for it, but i am looking for a well 
defined algorithm and maybe a computer program for the calculation.
also, are there any formulas, instead of graphs for calculating dB(A) out of 
dBSPL.
Thanx.

Itay (yaele at post.tau.ac.il)