The right-ear advantage for verbal stimuli shows the left hemisphere's specialization for language. According to a 1973 study, speech presented to the right ear in dichotic presentation shows stronger control over language mechanisms in the left hemisphere than the left ear. This shows that the act of competition between each ear is key, as right-ear advantage does not exist when sounds are presented one ear at a time. Another study in 1980 shows that the advantage in right handers is only restricted to a few consonants, but not any vowels.