Comment on "Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations".

Manley (, 16 September 2016, p. e1501814) report the splitting of a transverse acoustic phonon branch below in the relaxor ferroelectric Pb[(MgNb) Ti ]O with = 0.30 using neutron scattering methods. Manley argue that this splitting occurs because these phonons hybridize with local, harmonic lattice vibrations associated with polar nanoregions. We show that splitting is absent when the measurement is made using a different neutron wavelength, and we suggest an alternative interpretation.