metering and visual mastering tools
Modern audio gear and software comes loaded with meters to try and give visual indications of signal levels and a host of other information. The problem is that a lot of us don’t really understand exactly what our meters mean and what they’re trying to show us.
There are dozens of ways that understanding how to interpret meter readings can help you. To this end, we’re going to take a closer look at decibels, then examine some of the various meters, dials, gauges and indicators in more detail. This should help you understand how they all work and how they will be useful to you in your music making.
What’s a decibel?
The hardest part about metering is getting to grips with exactly what a decibel is. In fact, many experienced engineers and producers struggle with the scientific definitions.
A decibel is most accurately described as a logarithmic method for measuring the magnitude of a signal relative to a given reference level. Only when we know what the reference point is does the decibel measurement take on any real meaning. As such, there are a number of different signals that can be measured using decibels, although for audio purposes we’re mainly interested in acoustic sound signals and (analogue) electronic sound signals.
Part of the reason why so many people find this confusing is that most of the time, we foolishly insist on referring to each of these different measurements simply as ‘a decibel’ and abbreviating them all to ‘dB’. What we should be doing is specifying what the reference point is.
The result of this lazy naming is that we often have to infer the reference point from the context. There are three main areas where you’ll find decibels used for audio measurements, and the context should give you a clue about which type is being used.
Probably the most common everyday use of the decibel unit is as a measurement of the level of intensity of an acoustic sound. This is more accurately termed dB(SPL) and is referenced to sound pressure level in air, where 0dB(SPL) equates to 20 micropascals (uPa). This measurement of micropascal is the lowest pressure (and therefore quietest sound) that can be perceived by the human ear.
