I have added hearing to Eddie. Every time you take a step it makes a sound. The faster you move the louder your footsteps make a sound. A white bar at the lower left of the screen is a sound meter. If this line turns red, Eddie has heard you. Moving while crouching creates very little noise. Stay crouched to stay silent. When Eddie hears you, he moves slowly in the direction of the sound and circles the area where the sound was made.