A non-chiral ferroelectric nematic compound DIO was studied by dielectric spectroscopy in the frequency range 0.01 Hz to 10 MHz over a wide range of temperatures. The compound exhibits three nematic phases on cooling from the isotropic phase, viz. the ordinary paraelectric nematic N; intermediate nematic NX and ferroelectric NF phases. The lower frequency relaxation process P1 is similar to those observed in other ferronematic compounds. It is a continuation of the molecular flip-flop mode in the isotropic phase and corresponds to the collective movement of dipoles which are strongly coupled with splay fluctuations in the nematic phases. In addition to this process, the studied compound DIO shows another collective relaxation process in both paraelectric nematic phases. The high-frequency P2 originates from the polar/chiral domains which appear due to spontaneous symmetry breaking in achiral system. Both the collective processes, P1 and P2, show soft mode-like behavior on cooling to the NX-NF phase transition and therefore independently contribute to the formation of ferronematic phase
