Sound Track: Speaking of Specs

Specifications capture the essence of equipment performance. Understanding them will make you a savvy shopper.

When you're shopping for audio or video equipment, you should base your decision on three basic criteria: price, features and performance. Price and features are relatively easy to compare. Once you decide on a price range and select the features you need, you're "in the ballpark." The next step is to compare specifications. They are the true indicators of the equipment's performance, and they help you get the most bang for your buck.

But be careful. Comparing specifications can be a simple and straightforward process, or it can be a misleading mess. The trick is to make sure you're comparing apples with apples, not apples with oranges.

All specifications are measured relative to certain standards. The problem is that not all manufacturers use the same standards. Some manufacturers select a standard, or even create one, that makes their product look better than the competition's. Most independent testing laboratories use identical test methods and reference points, and are better information sources.

To determine which specifications are useful and which aren't, let's take a closer look at how we measure audio performance.

Units of Measurement
Sound loudness, or level, can range from nearly inaudible to ear-shatteringly loud. Measuring such a wide range on a linear scale would require very large numbers. So to make the numbers more manageable, engineers measure sound on a logarithmic (log) scale. The fundamental unit for measuring sound level is the decibel (dB).