The emission of electrons from metals can be excited through a variety of treatments and stimulated by thermal energy and as shown only recently, by high‐intensity ultrasound. Investigations were carried out on disks of 99.999% pure aluminum and aluminum 6061, exposed to acoustic irradiation up to 100 W/cm2at 20 kc/sec. The peak emission at certain intensity levels of the acoustic field is presented, compared with emission from thermal stimulation, and discussed from the viewpoint of acoustic activation of lattice defects in metal crystals.