These concerts were held on ceremonial occasions in the open air, in the village squares or in the courtyards of the houses.  They began in the morning and usually continued until nightfall, occasionally far into the night.  The musicians occupied the centre of the square and the trained singers stood or sat around them.  When the sign was given to begin, the two most skillful singers, sometimes a man and a woman, pronounced the first syllables of the song slowly but with a sharp emphasis;[25] then the drums began in a low tone, and gradually increased in strength as the song proceeded; the other singers united their voices until the whole chorus was in action, and often the bystanders, to the numbers of thousands, would ultimately join in the words of some familiar song, keeping time by concerted movements of the hands and feet.

Each verse or couplet of the song was repeated three or four times before proceeding to the next, and those songs which were of the slowest measure and least emotional in character were selected for the earlier hours of the festivals.  None of the songs was lengthy, even the longest, in spite of the repetitions, rarely lasting over an hour.[26]

The tone in which the words were chanted is described by Clavigero, Muehlenpfordt and other comparatively recent travelers as harsh, strident and disagreeable to the European ear.  Mendieta calls it a “contra-bass,” and states that persons gifted with such a voice cultivated it assiduously and were in great demand.  The Nahuas call it tozquitl, the singing voice, and likened it to the notes of sweet singing birds.

Sec. 6. THE INSTRUMENTAL ACCOMPANIMENT.

The Nahuas were not acquainted with any stringed instrument.  They manufactured, however, a variety of objects from which they could extract what seemed to them melodious sounds.  The most important were two forms of drums, the huehuetl and the teponaztli.

The word huehuetl means something old, something ancient, and therefore important and great.  The drum so-called was a hollow cylinder of wood, thicker than a man’s body, and usually about five palms in height.  The end was covered with tanned deerskin, firmly stretched.  The sides were often elaborately carved and tastefully painted.  This drum was placed upright on a stand in front of the player and the notes were produced by striking the parchment with the tips of the fingers.

A smaller variety of this instrument was called tlapanhuehuetl, or the half drum, which was of the same diameter but only half the height.[27] Still another variety was the yopihuehuetl, “the drum which tears out the heart,"[28] so called either by reason of its penetrating and powerful sound, or because it was employed at the Yopico, where that form of human sacrifice was conducted.