Particles represent the density of the medium. More particles = denser medium, like the difference between air and water.

Amplitude is the wave's strength - we perceive this as loudness. Bigger waves = louder sounds.

Frequency sets how many waves pass by per second - we hear this as pitch. More waves = higher pitch and shorter wavelengths (waves closer together).

Speed is how fast waves move through the medium. Real sound has a fixed speed determined by the medium itself. For example in air at 20°C sound travels at ~343 m/s.