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