Is there any ambient sound senor for arduino?
With the right type of microphone you can connect it to an analog input of the Arduino
Not sure I would agree with that. What is the right sort of microphone, it would have to be one with a built in amplifier.
...if a sound abnormally exceeds that sound level it starts flashing a LED.
Maybe I need another sensor to capture ambient sound too?
The brick includes a "high sensible microphone", but no amplifier, which isn't very "sensible".
Do you want one (which one) or both? The Arduino can do both in software (with a little hardware to create an amplitude envelope, a "DC" level that reflects the sound amplitude) or both can be done in hardware and the Arduino can simply read the two levels.
Jane Austin wrote a book about them. Sense and sensitivity.