The stimuli for hearing, or audition, aresound waves, which have several physical characteristics. The physical characteristic of amplitude or height of sound waves is transformed into the subjective experience of[Select], which is measured in units called[Select]. The frequency (cycles per second) of sound waves is transformed into the subjective experience of[Select], which for humans range from about 20 to 20,000 Hertz (HZ), the unit of measure for frequency.