MUNICH -- The ability to hear colors is apparently more frequent than has so far been assumed, the Munich-based medical journal **** Aerztliche Praxis **** reports.

According to the publication, the phenomenon does not only occur after drug intake. Although the exact number is unknown, it is estimated that one in every 2,000 people is able to associate certain noises or tones with colors.

Most of these so-called synesthetes are females, the journal said. Synesthesia is the excitation of one sensory organ after another is stimulated, DPA reported.

Hearing colors is independent of intelligence, education or personality characteristics, the publication adds. Synesthetes are normal, absolutely healthy people, as a rule, whose perception is not imbalanced. A team of researchers at the University of Leipzig is now examining the phenomenon and indications are that it may be hereditary.