The quasiparticle that represents quantized sound vibrations is the phonon.
A phonon is the quantum description of a collective vibration in a solid or another structured material. At the classical level, atoms in a crystal can oscillate in normal modes, much like masses connected by springs. When those vibrational modes are quantized, each discrete unit of vibrational energy is treated as a phonon.
Phonons are often compared with photons: a photon is a quantum of electromagnetic radiation, while a phonon is a quantum of mechanical vibration. Long-wavelength acoustic phonons behave like sound waves, with neighboring atoms moving in coordinated patterns. Materials with more than one atom in their repeating unit cell can also support optical phonons, in which different atoms oscillate against one another.
Phonons are not fundamental particles floating freely through empty space. They are emergent quasiparticles whose properties depend on the material’s lattice and interactions. They help explain thermal conductivity, electrical resistance, sound propagation, and how crystals scatter neutrons. The concept was introduced by physicist Igor Tamm in 1930, and the name comes from the Greek word for sound or voice.