How do I use Sound Sensor LM393 + Speaker in Arduino
This post was awhile ago, but I wanted to offer some more definitive info for others like myself who were trying to identify it. What you have there is the Keyes KY-037 "high-sensitivity voice sensor" module. Mine came with the Inland Arduino Uno RFID Learning Kit.

Apparently the KY-037 and the KY-038 are the same except the KY-037 has a higher sensitivity microphone. I could not find any specs to quantify what that sensitivity difference is, however. Both have a LM393 voltage comparator on the board. The same Arduino code ought to work for both.

Here are a few helpful links I found, some also showing a bunch of the other Keyes modules and how to use them:

http://linksprite.com/wiki/index.php5?title=Advanced_Sensors_Kit_for_Arduino

http://brd4.braude.ac.il/~ksamuel/ElIn.31361/Lectures/022-Basic%20Definitions%20and%20Concepts%20Sensors%20and%20Actiators%202013-10-10.pdf  (Page/slide 40)

tkkrlab.nl/wiki/Arduino_37_sensors