Albedo is the proportion of insolation that is reflected back by the surface. It depends upon the nature of the surface upon which the solar radiation is incident and the angle of incidence of the solar beam.
Mesa is an elevated area of land with a flat top and sides that are usually steep cliffs. Mesa is exclusively used to refer to landforms built of flat lying strata.
Ultrasound refers to a sound wave with a frequency greater than the upper limit of human hearing, which is generally over 20 kHz. In general, humans can hear sounds with a frequency between 20 Hz and 20 kHz.