  In the present work we determine the speed of sound in a Bose-Einstein
condensate confined by an isotropic harmonic oscillator trap. The deduction of
this physical parameter is done resorting to the $N$-body Hamiltonian operator.
The single-particle eigenfunctions that have been employed in this formalism
are those stemming from the corresponding harmonic oscillator potential, and an
expression for the dependence of this speed on the temperature is also deduced.
These functions are used in the calculation of the scaterring length, etc. The
situation for a Bose-Einstein condensate of sodium is evaluated and the
corresponding speed of sound is obtained and compared against the known
experimental outcomes. The possibility that the solution, to the existing
discrepancy between experiment and theoretical predictions, could be given by
the Zaremba-Nikuni-Griffin formalism is also explored.
