•I have characterized my target sounds in three frequencial components (Hz), with their amplitude (dB). And I only want to compare the sound measured with these components but I can't split them from audio samples I have taken.
I'm not sure I understand... If you have a truck and a trumpet at the same time, and you want to filter-out the truck, that's virtually impossible.* Except, you can filter-out low frequencies such as "rumble" from the truck.
If the sounds are not occuring at the same time, you have a better chance of automatically separating them. But of course, not all trucks generate the same frequencies at the same volume, and a trumpet can play many different notes and can be played/recorded at various volumes. There is no simple "fingerprint" for either of these sound-sources.
* "You can't un-fry and egg, you can't un-bake a cake, and you can't un-mix a recording."
If you could do that, there would be no need for multitrack recording... You could record the whole band with one microphone at once, un-mix, edit, and then re-mix. That technology does not exist.