Answer:
the kind of material it is moving through
Explanation:
Sound wave is a type of mechanical wave, which requires a medium to travel, unlike longitudinal waves that can travel through vacuums. Since, sound waves travel through mediums, the KIND OF MEDIUM/MATERIAL it is traveling through has a role to play on how fast it moves.
Sound waves move faster in materials whose molecules are closely packed together than those with loosely packed molecules. This is why sound waves naturally travel faster in SOLID materials. Therefore, the the kind of material the sound wave is moving through affects how fast it moves.