At a concert or near a loud speaker, bass can feel like a thump in your chest or feet. Sound is a mechanical wave, so it transfers energy by making particles vibrate. Low-frequency bass can make speaker cones move backwards and forwards through relatively large distances. Those vibrations can pass into the floor, walls and nearby objects. Your body can detect some of these vibrations through touch as well as through your ears. That is why very low notes can be felt as much as heard. The effect is a useful reminder that sound needs matter to travel through and that waves can transfer energy without carrying the material itself along with them.

The useful part of this physics is that it helps people predict and design real things. Engineers often begin with the same simplified model used in school, test where it works, then add more detail when measurements show that the real situation is more complicated.

Waves transfer energy and information without transferring matter from source to receiver overall. Frequency tells us how many oscillations pass each second, wavelength is the spacing between matching points, and wave speed links them through v = fλ. Different frequencies interact with materials differently, which is why engineers can choose particular parts of the electromagnetic spectrum—or particular sound frequencies—for sensing, communication, heating or imaging.