{HEAD ~ Each} of {TAIL ~ these spectral regions} is defined by a respective center frequency within a common frequency range 
of
{ HEAD ~ Each } of { TAIL ~ these spectral regions } is defined by a respective center frequency within a common frequency range
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH