Twenty-six healthy volunteers participated in the study. All
were right-handed and without deficits in hearing. Handedness
was assessed by a questionnaire adapted from the Edinburgh
Handedness Inventory [20]. The subjects were assigned to two
groups according to their age: a young group (YG), comprising 8
males, 6 females, mean age 26.3 years, age range 25–31 years, and
an old group (OG), consisting of 8 males, 6 females, mean age 55.4
years, age range 48–60 years. The study was performed with the
approval of the local ethics committee. All subjects gave a written
informed consent according to the Declaration of Helsinki prior to
participating in the study and after being thoroughly instructed
about the nature of the experiment.