Saru Mayo

The quality of sound reproduction within and enclosed space is largely dependent upon the room acoustics of the space. Room acoustics are the term applied to the interaction between the sound waves originated from any sound source and the surfaces within the room. Walls, floors, ceilings, furniture and even people in the room can change the way sound is perceived by listeners within the room.

Surfaces that are very hard and smooth reflect sound best, while those that are soft and yielding and which do not present flat surfaces bigger than the sound waves that are hitting them are the best are reducing echoes and unwanted reflections. Sound waves produced by an average musical passage range from very, very small to 50 feet or more in length. Larger waves are produced by the lower bass frequencies, while small waves are made by higher pitched sounds.

In smaller rooms, the large bass waves can be folded back upon themselves as they reflect off a wall or other solid surface. When the reflected wave overlaps itself or another following wave, the energy of the two waves interacts. Depending upon which portions of the wave, a peak or a valley, are interacting, the result can be an unnatural boost or a partial cancellation of the original note. As waves of different frequencies play upon echoes, the original music or other sounds can be badly distorted, making them unpleasant at best, and completely unintelligible at worst.

You may have experience the deleterious effects of room acoustics firsthand if you have ever tried to make out the announcements made over the public address system at most airports. Airport buildings often have large glass windows that provide excellent reflective surfaces. When combined with vast open expanses of hard tiled floor and long corridors, most airports could not be better designed as echo chambers even if the architect had tried.

Acoustic engineers and sound management professionals have an excellent knowledge of how sound waves react with various building materials and with rooms of various shapes and sizes. Using this knowledge they can correct room acoustics to make them as close to acoustically neutral as possible. By adding acoustic panels of materials like Owens Corning 703 or other acoustic damping material, they can reduce the effect of echoes within a room.

Buildings where sound quality is important can be designed for good acoustic performance before they are built. Experts in church acoustics, for example, are often consulted when new houses of worship are in the design stage. While room acoustics often come into play in large public spaces, they also play a strong role in the quality of sound reproduction in smaller, residential spaces as well. The popularity of home theater rooms has led to an increased demand for affordable, DIY acoustic room treatments.

Understanding the complex interactions between sound waves and the space within which they are produced can help designers make sure that a room sounds as good as it looks.