The spectrum of harmonic frequencies of pulse width modulator output signal y is spread out to decrease {TAIL ~ peak energy levels} of {HEAD ~ PWM output signal} y 
The spectrum of harmonic frequencies of pulse width modulator output signal y is spread out to decrease { TAIL ~ peak energy levels } of { HEAD ~ PWM output signal } y
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH