The proton spin-lattice relaxation time (T-1) dispersion was studied under simultaneous sonication in the nematic phase of 5CB. It appears that metastable ordered states subject to a memory effect can be induced by the combined action of an amplitude-modulated ultrasonication and a pulsed magnetic field. We argue that the acoustic amplitude modulation adds instability to the nematic phase through director order fluctuation enhancement. Different manipulated states of the director were unambiguously identified by the Larmor frequency dispersion of T-1. The field-cycling NMR technique was used for T-1 measurements. (c) 2007 Elsevier B.V.. All rights reserved.