It doesn't to any real extent. Here, from Wikipedia, because the text from my aerodynamics textbook might make your little head assplode:
" (The speed of sound) is proportional to the square root of the absolute temperature, but is independent of pressure or density for a given ideal gas."
And with context:
"The speed of sound in an ideal gas is independent of frequency, but does vary slightly with frequency in a real gas. It is proportional to the square root of the absolute temperature, but is independent of pressure or density for a given ideal gas. Sound speed in air varies slightly with pressure only because air is not quite an ideal gas. Although (in the case of gases only) the speed of sound is expressed in terms of a ratio of both density and pressure, these quantities cancel in ideal gases at any given temperature, composition, and heat capacity. This leads to a velocity formula for ideal gases which includes only the latter independent variables."