Pythagoras healed people with music played from a lyre with "7" strings. 

Seven

In every system of antiquity there is a frequent reference to this number, showing that the veneration for it proceeded from some common cause.  It is equally a sacred number in the Gentile as the Christian religion.  Oliver says that this can scarcely be ascribed to any event, except it be the institution of the Sabbath.  Higgins thinks that the peculiar circumstance, perhaps accidental, of the number of the days of the week coinciding exactly with the number of the planetary bodies probably procured for its character of sanctity.  The Pythagoreans called it a perfect number, because it was made up of 3 (spiritual)  and 4 (physical), the triangle and the square, which are the two perfect figures.  

I've read Pythagoras also played an instrument that is referred to as an ancient form of guitar, a Momochord.

A single string instrument. 1

~ The "Tetrad" or "triangle" of numbers of the soul.

~ The 7 planets that Pythagoras spoke of and that earth was the center point. 

** My thoughts ** 

Wouldn't it make since that the pyramids, were more like resonance producers, water deep under the pyramid.

to create an air system, ionzer? Power ?

They could heal anything with sound.

All you would have to know is the tone needed. Perfect harmony/resonance .... maybe that's why the the harmonic measure "A" was changed from 432 (the perfect harmony of the universe) to 440. That subtle change would change EVERYTHING! 

Music. This is why we humans are so drawn to music, it's a sound that helps us to resonate with the All.  ALL healing.

Mental, physical, the soul. 

Soul. The balance between worlds. Etheral, physical. 

Wouldn't it be wonderful if the answer to what "everyone" was looking for was as simple as a harmonic tone. Wouldn't that make complete sense that we, the human race could all be healed from disease, mental illnesses, just by harmonizing? 

~  Umberto Eco, Art and Beauty in the Middle Ages  ~

This triangular figure of numbers in the shape of the Greek letter Lamda is the Tetrad of the Pythagorians.

As was discussed by Plato in his dissertation on the Composition of the Soul, it is a set of numbers whose relationships with each other seemed to summarize all the inter-dependent harmonies within the universe of space and time.

Thus to have established the relationship between music and space/number fired the imagination of the Pythagorians and was taken up especially by the School of Plato and the subsequent Neo-Platonists. Pythagoras himself wrote nothing which has survived, and so it is the Platonists we have to thank for recording and developing what had hitherto been passed down through two hundred and fifty years of oral tradition.

Pythagoras taught that each of the seven planets produced by its orbit a particular note according to its distance from the still centre which was the Earth. The distance in each case was like the subdivisions of the string refered to above. This is what was called Musica Mundana, which is usually translated as Music of the Spheres. The sound produced is so 

exquisite and rarified that our ordinary ears are unable to hear it. It is the Cosmic Music which, according to Philo of Alexandria, Moses had heard when he recieved the Tablets on Mount Sinai, and which St Augustine believed men hear on the point of death, revealing to them the highest reality of the Cosmos. (Carlo Bertelli, Piero della Francesca, p. 60.) This music is present everywhere and governs all temporal cycles, such as the seasons, biological cycles, and all the rhythms of nature. Together with its underlying mathematical laws of proportion it is the sound of the harmony of the created being of the universe, the harmony of what Plato called the "one visible living being, containing within itself all living beings of the same natural order".

For the Pythagorians different musical modes have different effects on the person who hears them; Pythagoras once cured a youth of his drunkenness by prescribing a melody in the Hypophrygian mode in spondaic rhythm. Apparently the Phrygian mode would have had the opposite effect and would have overexcited him. At the healing centers of Asclepieion at Pergamum and Epidauros in Greece, patients underwent therapy accompanied by music. The Roman statesman, philosopher and mathematician, Boethius (480-524 A.D.) explained that the soul and the body are subject to the same laws of proportion that govern music and the cosmos itself. We are happiest when we conform to these laws because "we love similarity, but hate and resent dissimilarity". (De Institutione Musica, 1,1. from Umberto Eco, Art and Beauty in the Middle Ages. p. 31).

The ref. above is cited from here; http://www.aboutscotland.com/harmony/prop.html