Can't distinguish the sound but it's reason enough to check things out. Valve tapping, exhaust leak, fuel injectors, timing chain (not sure on this one)...? The manual suggests using a high viscosity oil treatment if you suspect a stuck lifter. After the engine warms I hear it at idle and while driving; plus the plugs are tight. I'm going to change the oil since it's time, (I only use synthetic Motorcraft or Mobil1 5-20) and add a treatment. But not sure on brand. Wondering other possible causes, and your guys/gals' experience. Thanks.

 

what engine, miles?