Results of optical-acoustic researches of thermal and shock influence on change of elastic properties and durability of metals due to reorganization of their structure are submitted in the paper. To reveal the scales of modifications, we study iron, nickel, copper, and aluminum alloy specimens with various initial structures before and after shock loading. The loading was accomplished by pressure impulses of amplitude ∼1.0GPa and duration ∼8*10 ^-8s. The initial structure of the specimens was modified by vacuum annealing for 1 hour at a given temperature. After the annealing, the specimens were cooled in a furnace. Measurements of elastic waves in two orthogonal directions are carried out by the pulsed opticalacoustic method before and after shock loading. The analysis of velocities allows to determine changes of material elastic properties and to estimate the contribution of different mechanisms of plastic flow to hardening metals with various initial structures. The pulse optical-acoustic method allows to carry out measurements over a wide spectral range. It gives a chance to obtain frequency dependences of the attenuation and acoustic velocity in metal samples after preliminary heat treatment and shock hardening. The analysis of changes of the dependences allows to estimate scales of structural reorganizations which have occurred in the samples due to shock loading. It is shown, that the rotational machine of plastic flow is the basic in samples with the grain size ∼ 20μm, and the dislocation and twin mechanisms - in coarsegrained samples. With this method, one can gain information on restructuring on a scale of ≥10 ^-7 -10 ^-6m.