Because our auditory system is non-linear with respect to frequency response and listening level, our perception of audio does not equate exactly with the terms used to describe those differences. In practical reality the decibel system is not perfect. Understanding this distinction is important. By contrast, power (dBm) implies that 3 dB is considered twice as loud. Sound pressure level (dBspl) for example, implies that twice as loud is defined as a 6 DB difference. Unless the person you are communicating with understands the reference implied, the number associated with the term dB is meaningless. The term dBspl, is used to describe the sound pressure level with a reference of 20 micro pascals. The term dBv, for example is used to describe voltage level with a reference of. Thus, a descriptive term will follow the dB in order to define that reference. The reference relates to what technical aspect you are actually measuring. The term dB is meaningless unless the reference is defined. In order to make the decibel system more practical for describing audio in its many forms, ratios are used to help simplify all of the math. This greatly simplifies our ability to describe our experience of levels and audio. Thus, a linear way of describing audio becomes more practical to the audio engineer and equipment designer. As you can see in the 1st example twice as loud is a difference of 90 whereas in the 2nd example twice as loud would be a difference of 900.įor practical purposes, logarithms are used to make these numbers linear so that they are not relative to the starting point. If you start at 100, however, twice as loud would then become 1000. What this means is that the numbers used to describe those measurements will vary greatly based on the starting point.įor example: if you define an audio voltage level as being the number 10, twice as loud as him would be defined as 100. From a technical point of view the measurement of audio is logarithmic. The purpose of the decibel scale is to make a nonlinear a system linear. The ability to quantify and communicate level changes of any kind would be very limited. Without a reference system, working with audio would become entirely a matter of individual perception and guesswork. This provides a valuable reference tool for the audio engineer, technical engineer, and the audio equipment designer. The decibel can be used to measure sound pressure level, sound intensity level, voltage level and power, just to name a few.
The decibel scale can be used to measure audio in a variety of different ways. What Can Be Measured By The Decibel Scale
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