Sound Activated Switch ( also known as clapper)

hi all, i am doing a project of the circuit below which is sound activated switch, this circuit will receive about 5Khz, which is also avoid our vocal sound.

this circuit is working, if you want you might try it, but my problem is if i want to upgrade or modified this circuit to become more better, what can i do on it and also what should i do?

hope some1 can help me with this.

thx you

EEK! A fuzzy JPG.
Please save and attach schematics as a clear GIF or PNG file type.
The circuit doesn't have much frequency filtering.
The old LM358 barely works as high as 5kHz.
IC1A amplifies the mic's signal, then R5 and R6 attenuates it.