Motivation

The motivation for this project stems from the experiences I had driving with my grandmother. On many occasions, when an emergency vehicle is approaching the car, my grandmother wouldn't hear the sirens until the emergency vehicle is right behind her. But by then she panics and freezes and puts parks the car in the middle of the road making the emergency vehicle have to go around her. I realized that the root of the problem is that she didn't hear the sound ahead of time to take the necessary precautions. A device that will alert her that an emergency vehicle is approaching would be ideal for her and the other 38 million Americans that suffer from hearing loss.   

Design Decision

I had a limited amount of resources to work with but that actually was not a big deal.  I knew that product had to be simple that it can sit on the dashboard of any vehicle. Thus, a small box that is unobtrusive in a vehicle seemed like the right approach. Additionally, my grandmother would appreciate objects that are simple to use that is not flashy that it distracts her from driving. The LED's flash in a a cool blue mainly because I wanted  something that is soothing. Colors like red would signal trouble, danger etc. Blue rather is associated  with peace, serenity, ethereal, spiritual, and infinity. 

The set up

A small mic is attached to an Arduino that receives digital input from the environment. 

All of that is tightly packaged into a standard black encasing that can be placed anywhere in your car. A USB is attached to the device for easy power from your car battery outlet. 

Code 

The code was the sample code given with slight adjustments. Rather than analog, the receiver was switched to digital for the output. Further, I adjusted by changing the arrays size to 500 to make the LED light up much smoother. The outputting signal is the signal input -30 so show the progression of the light as the sound gets closer.