The need for micro-mechanics based understanding leading to meso-scale models for understanding relation between microstructure and ultrasonic higher harmonic generation is emphasized. Three important aspects of material behavior, namely tension-compreßion asymmetry, shear-normal coupling and deformation induced anisotropy that are relevant to ultrasonic higher harmonic generation are identified. Of these, the role of tensioncompreßion asymmetry in micro-scale material behavior on ultrasonic higher harmonic generation is investigated in detail. It is found that the tension-compreßion asymmetry is directly related to ultrasonic even harmonic generation and an energy based measure is defined to quantify the asymmetry. Using this energy based measure, a homogenization based approach is employed to quantify the acoustic nonlinearity in material with micro-voids and the findings are discußed.