Imagine thousands and thousands of penguins gathering for mating season after six years of being at sea. Each one has its own particular partner, and somehow the pairs all manage to find each other among the crowd. How do they do it? The answer, according to Radka Šindlerová, is that penguins, like humans, each have a distinctive voice. The idea that each voice is unique is also the basis for overtone music, which is taught and celebrated at a festival in Prague every year.

"Every voice has its own 'color' or characteristics," explains Šindlerová, one of the organizers of the Overtone Festival. "Overtones are the elements in the spectrum of 'colors' which make our voices unique." The musical possibilities of harnessing these elements of sound is gaining a growing following in Europe, and the Prague festival is one of the biggest gatherings of overtone devotees.

"The festival represents the continuing stream of musical traditions from many nations, coming to us in a new way from old traditions," Šindlerová says. "Above all, [the festival represents] the strong influence of the power of singing on the psyche of man."

Highlights of the festival include a workshop led by Regina Lindinger, who will demonstrate an intuitive singing technique she developed called Voiceflow. A respected music therapist in Germany, Lindinger will be making her first appearance lecturing and performing in Prague.

Another event that comes highly recommended is the concert by Mongolian singing troupe Hosoo & Transmongolia. Overtone performers from Mongolia are of particular interest because the music is indigenous to their culture. "Mongolians are the strongest in this type of music because they practice it from birth," Šindlerová explains. "It's a normal part of their culture. They sing it even at home with their families."

Indigenous practitioners from Mongolia, Tibet, Siberia and the surrounding area comprise one of two schools of overtone music. The other, younger school has its origins in Europe during the '60s. This more orchestra-based stream will be showcased in the festival's "Water Live Show," and will also be the focus of Sunday's workshop by Chris Amrhein, who is credited with being the godfather of the festival.

The Friday night water show is new this year, and will be preceded by a lecture by Alexander Lauterwasser explaining the effect of sound vibrations on water. The lecture will be in German only, but is expected to be primarily a visual presentation. Both the lecture and concert will feature large screens on which vibrations in water will be made visible as colorful mandalas and geometric patterns.

The effect of sound vibrations on water is fundamental to overtone music, Šindlerová says, "because we are water. Seventy percent. This is why sounds influence our psyche so much." She goes on to say that musical sounds, as opposed to ordinary or chaotic sounds, create organized, geometric patterns in water vibrations, and that something similar happens when sound penetrates a human being. "When tones enter us, our whole body listens, and it accepts and makes special geometry, affecting our insides so that we feel very relaxed and happy."