Overview

I often say that when you measure what you are speaking about, can express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind. It may be the beginning of knowledge but you have scarcely, in your thought, advanced to the stage of Science whatever the matter may be.-Lord Kelvin.

Measurements have always been critical to science as they allow us to put assumptions, theories, and equations to the test of reality. As a result, scientists have always been looking for ways to improve the availability, accuracy, and precision of measurements. The science of room acoustics is no exception.

High-fidelity sound reproduction involves the frequency range from 20 to 20,000 Hz. This range of frequencies includes acoustic waves with wavelengths ranging from a single centimeter to nearly 20 meters. As the previous chapters of this book have shown, the dimensions of rooms and loudspeakers also fall within this range, making them subject to various acoustic effects due to diffraction, resonances, boundary effects, and reflections. Given the extremely complex nature of acoustics, these effects are often very difficult to model with a useful level of precision. Therefore, measurements are the most reliable way to accurately quantify room acoustics.

Fortunately, acoustical measurement tools are now more available and affordable than ever. Much of this is due to the recent popularity of the personal computer and the evolution of digital signal processing. In this chapter, we will...