Once sound was thought of as a signal to be sent and received, a room's reverberation stopped counting as part of the sound and became interference. Engineers working with microphones and amplifiers began treating sound in a room as if it were a signal in a circuit, and they wanted the same control over both. The result was a prized new sound that was clear, direct, efficient and free of echo.
Sound-absorbing materials were brought in to shut out the din of machines, traffic and factories. But they did more than remove noise: they gave interiors a distinctive deadened sound of their own. A technology meant to subtract becomes a source of the next era's character.
A soundscape is two things at once: the physical environment of sound and the way people perceive that environment. Change either one and you change what is heard. So when new machines and materials remade rooms, they also remade the ears that listened in them.
The same tools that let builders control sound, such as absorbent tiles, sound meters and reverberation formulas, were used to produce one standard sound everywhere. Concert halls, office towers and film studios began to sound alike. A room's acoustics stopped telling you where you were.
Radios, amplified record players and talking pictures did not just carry sound. They taught people new ways of listening. Buying sound as a product made audiences more conscious of what they heard and more demanding about which kind of sound they wanted, and that shared taste in turn pushed the technology forward.