While seismic waves and sound waves both propagate through different mediums, it is possible for humans to perceive the acoustic energy associated with an earthquake before the arrival of seismic waves. This phenomenon is known as the "precursory sound" or "earthquake sound."
The precursory sound is not the direct propagation of seismic waves that travel faster than sound waves. Instead, it involves the transmission of airborne sound waves that are generated by various processes associated with an earthquake, such as the movement of rocks, fracturing, and ground shaking. These processes can induce vibrations in the air and other mediums, leading to the generation of audible sound waves.
The speed of sound in air is much slower than the speed at which seismic waves travel through the Earth. Therefore, if the epicenter of an earthquake is relatively close to the observer, the airborne sound waves generated by the earthquake can reach the observer's location faster than the seismic waves.
In some cases, the intensity of the precursory sound may be significant enough for humans to hear and perceive it as a rumbling or roaring sound before the arrival of the more powerful seismic waves. However, it's important to note that the precursory sound is typically only heard in close proximity to the earthquake's epicenter and for relatively small to moderate earthquakes.
For larger earthquakes occurring at greater distances, the time delay between the generation of the precursory sound and the arrival of seismic waves becomes more significant, making it less likely for humans to perceive the sound before feeling the ground shaking.
It's worth mentioning that the ability to hear the precursory sound depends on various factors, including the geological characteristics of the region, the distance from the epicenter, the intensity of the earthquake, and individual sensitivity to sound.