Which of the following is deemed incorrect regarding decibels?

The assertion that decibels never represent a negative value is incorrect because decibels can, in fact, have negative values depending on the context in which they are used. For example, when measuring sound intensity, decibels are often referenced against a standard level of sound pressure, and values below this threshold are expressed as negative decibels. This logarithmic scale means that decibels can effectively represent very low levels of sound or power, allowing for a wide range of values including those below zero.

The other statements provide accurate reflections of decibels. They are commonly used to measure sound intensity (the first statement), can indeed be expressed as an absolute measurement in relation to a reference level (the second statement), and they inherently denote a logarithmic scale (the third statement). Understanding the nature of decibels as a logarithmic unit helps to clarify how they can accommodate a broader spectrum of measurement values, including negative values.