Every surface that sound encounters has the ability to change it—to reflect, absorb, scatter, or refract it. Although the human ear perceives sound as something immaterial, its behavior in space depends directly on the physical characteristics of the environment through which it passes. In architecture and interior design, the acoustic properties of materials are crucial to the feeling of comfort, speech clarity, music reproduction quality, and even the psychoacoustic impact on humans. Four of the most common materials in construction—concrete, wood, glass, and textiles—have radically different "sound signatures."
Concrete – hardness, reflection, and long reverberation time
Concrete is one of the densest and hardest building materials. This property makes it excellent at reflecting sound waves, but a poor absorber. Sound waves reaching a concrete surface are repelled almost completely without losing a significant amount of the energy they carry. This leads to a long reverberation time—a phenomenon in which sound continues to resonate in a room even after the source has stopped emitting sound signals.
In rooms with large concrete surfaces (such as industrial halls, underground parking lots, or sports halls), strong echoes and speech intelligibility issues can be observed. This type of "hard sound" can be unpleasant to the ear and tiring during long stays in a particular room. For this reason, in modern acoustic architecture, concrete is almost always combined with materials that have high sound absorption properties, such as acoustic panels, perforated ceilings, or textile elements.
Wood – a natural balance between reflection and absorption
Wood has unique acoustic properties that make it one of the most valued materials in concert halls and studios. Depending on the type, density, and grain direction, wood can reflect some of the sound while absorbing certain frequencies.
This selective sound absorption gives wooden surfaces a "warm" and "natural" tonal character. Solid smooth boards reflect higher frequencies, while softer or porous woods (such as pine or alder) absorb low and mid frequencies. This property allows wood to "soften" the sound environment without muffling it—something that concrete cannot do.
For this reason, many concert halls and chamber music venues often use richly decorated wooden paneling—not only for aesthetic reasons, but also to control reverberation and ensure natural sound diffusion.
Glass – a mirror for sound waves
Glass is another hard and smooth material that hardly absorbs sound. Its density and smoothness make it an "acoustic mirror" that reflects sound waves with minimal attenuation. That is why in rooms with large glass surfaces, sound often sounds "sharp" and "metallic."
For this reason, architects and sound engineers avoid excessive use of glass in rooms intended for speech, music, or recording. When glass is unavoidable (e.g., in offices or public buildings with panoramic facades), curtains, carpets, acoustic panels, or furniture are added to soften reflections.
Interestingly, laminated and double glazing can have different acoustic properties. The intermediate layer or air gap between the panes partially absorbs sound energy, reducing noise transmission between rooms—especially in the low-frequency range.
Textiles – soft absorbent and acoustic "shock absorber"
Textiles, whether curtains, carpets, or upholstery, are a classic example of a material with high sound absorption capacity. Thanks to their porous structure and flexibility, textile fibers capture sound waves, converting acoustic energy into heat through friction and microvibrations.
The thicker and softer the fabric, the better it absorbs sound. Thick velvet or wool fabrics effectively absorb high and mid frequencies, eliminating echoes and reducing reverberation time. This is why rooms with lots of textiles—such as theaters, movie theaters, or living rooms with carpets and curtains—sound "warm," intimate, and unobtrusive.
Interaction between materials – acoustic balance
In a real architectural environment, you almost never find just one material. The effect on sound depends on how they're mixed. You get the best acoustics by carefully balancing reflective and absorbent surfaces.
For example, concrete provides strength and density to sound, while wood adds natural warmth and richness to the timbre. Glass adds brightness and definition, and textiles soften and stabilize the sound field.
This acoustic synthesis creates a harmonious sound environment in which sound is not lost, but also does not strain the ears.
In conclusion, we can summarize that every material truly "sounds" in its own way. Concrete is hard and echoey, wood is warm and harmonious, glass is sharp and ringing, and textiles are soft and absorbing. Understanding these acoustic properties is not only a technical necessity but also part of the art of spatial design. By combining materials correctly, we can shape not only the way a room looks, but also the way it "sounds"—i.e., its acoustic character, which often goes unnoticed but is felt with every word, every note, and every breath.
