First instinct was a stuck lifter, but the ticking would increase with the rpms. Other things could be arcing from a plug wire, bad pulley, broken rocker arm/spring. I am a little puzzled. Almost all engine ticking sounds would increase with rpms. So that brings us to the tranny, and you said taking the car out of gear(ie putting it in N or P) stops the sound. Getter in the air and put it in gear, don't get under the car unless you have to, and listen. Let us know if you need help or if you solve.