Does altitude change the sound of speakers??

Too many variables. Temperature, altitude and humidity and seismic characteristics, to name a few.

"So if can’t hear a fart in space, can you smell one, or does that go hand in hand."

Assuming you do have a helmet and oxygen supply, you are not likely to smell it. Without it, it probably depends on how close you are to the source and how long you can stand without breathing much else.

To find your answers to these and other pressing questions, read Mary Roach, author of Packing for Mars, and other scientifically tangential books. 

Actually, it was from the first Alien movie advertised as “in space, no one can hear you scream”. I still have the movie poster.

Yes but my kid brother had the "In space no one can hear you fart" T-shirt. 

 Boy, this thread sure went in the proverbial toilet quick!!