What is true about the speed of waves as they travel through different materials?

Sound waves travel faster in liquids and gasses, compared to solids, where they travel slower.

Comparably for gasses and liquids, it is harder for waves to get across gasses because the particles are more spread out.

If you want to research more about it, look into the two main properties that impact how fast a wave can go and if it can even pass through, the elastic properties and density itself.