Sound waves can pass through walls due to a phenomenon known as sound transmission or sound propagation. When a sound wave encounters a solid object like a wall, several factors determine whether the sound is transmitted through the wall or not.
Elasticity and density: The ability of a material to transmit sound depends on its elasticity and density. Sound waves are mechanical waves that require a medium to propagate. Solids, including walls, have high elasticity and density compared to gases or liquids, making them better at transmitting sound. When a sound wave reaches a wall, it can cause the wall's particles to vibrate, allowing the sound energy to be transferred to the other side.
Thickness and composition: The thickness and composition of the wall also play a role in sound transmission. Thicker walls generally provide better sound insulation as they offer more material for the sound wave to interact with and lose energy. Additionally, walls made of denser materials like concrete or brick tend to block sound more effectively than thinner walls made of lightweight materials like drywall.
Sound frequency: Sound waves consist of different frequencies, which correspond to different pitch or tone. Higher frequency sound waves, such as those produced by a whistle or a bird chirping, tend to be more easily blocked or absorbed by walls due to their shorter wavelength. Lower frequency sound waves, such as those produced by bass-heavy music or a rumbling engine, have longer wavelengths and can pass through walls more effectively.
Despite these factors, no wall is completely soundproof. Some sound waves will still be transmitted through walls, although their intensity may be reduced. Specialized construction techniques and materials can be used to improve sound insulation in buildings, such as adding insulation layers, using double walls, or incorporating sound-absorbing materials to minimize sound transmission.