how to change lowPassResults value in decibel

Question

lowPassResults = ALPHA * peakPowerForChannel+ (1.0 - ALPHA)* lowPassResults;

i m changing this value in decibel through this function.

decibels = 10 * log10 (lowPassResults); then if lowPassResults value is .00001 then 50db and lowPassResults value is .0000001 then 70db

But if it is detecting less noise then it is giving less value and if it is detecting more noise and it is giving more value.. so how can i get right decibel value from this variable lowPassResults???