Аннотация:Linear non-stationary dynamic problems describing transient wave processes in deformable solids are consideredunder the assumption that the perturbation propagation region is limited. The statement of the problem is formulated in ageneralized form, it is understood that the linear constitutive relations can express the interconnection of the parameters ofthe stress-strain state with the temperature field, with the electric and magnetic fields and other physical characteristics. Inaddition, it is assumed that the material of the body can have viscoelastic properties in the framework of the linearBoltzmann-Volterra model. The integral Laplace transform with respect to time is applied to the equations and boundaryconditions, taking into account the initial conditions. A theorem is formulated and proved. This theorem establishes aconnection between the branch points on the complex plane of the solution of the non-stationary problem in images andthe properties of the spectral set of the problem of free vibrations of the body under consideration, as well as the initial dataof the non-stationary dynamic problem. The established property of solutions to the problems of the type underconsideration in images in many cases facilitates the process of constructing solutions in the originals. An exampleillustrating the formulated theorem is given.