The undesired periodic noise is coupled via ground and {HEAD ~ the battery} into {TAIL ~ the signal processing path} 
into
The undesired periodic noise is coupled via ground and { HEAD ~ the battery } into { TAIL ~ the signal processing path }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL