Tips for an Arduino project involving audio db level sensing

I'm thinking of putting together a small Arduino project for a practical purpose. My first project.

The goal is to make something that will measure the current db level of the room. Output the current db level on a LCD screen. And also light up a red LED if the db level is above a certain range and the time is within a specific range. Though if the LCD isn't at a price point I'm happy with I may opt instead to send something over the LAN.

Does anyone have suggestions on the best hardware to use and any other tips for this project? Namely the db level sensing part. I see stuff on various types of audio input but nothing on db levels.

I had a similar idea but a graphic analyzer instead. Unfortunately I don't have anything either..

mangomango: I had a similar idea but a graphic analyzer instead. Unfortunately I don't have anything either..

Something like http://www.instructables.com/id/LoL-Shield-Audio-Spectrum-VU-Meter/ perhaps?

Yes but with an LCD