Picture of Sound Activated Camera Trigger For High Speed Photography
To make a sound activated camera trigger the main thing you need is a camera that accepts an external trigger. 

The camera I’m using for this example is a Samsung NX1000 Smart Camera. The camera is activated when the external trigger contacts are shorted to ground; so the circuit we’re making shorts a signal to ground whenever there is a “loud” noise.

Components List:
     •SimpleCircuit Microphone Board
     •SimpleCircuit Comparator
     •SimpleCircuit N-Channel MOSFET

All Simple Circuits can be found on our Kickstarter Page 

Step 1: The Schematics

Picture of The Schematics
The first schematic is the Microphone circuit (Single Supply). 

Connect the output of the microphone to the voltage comparator circuit (Second Schematic)

Connect the output of the Comparator to the N-CH MOSFET

Connect the Drain of the N-CH MOSFET to the camera trigger 

The third Schematic is the entire design redrawn with Simple Circuits! 

5V for VCC works well. You could go as high as 12V or as low as 3.3V if you need to.