The scientific “unit” we call the decibel (lcamtuf.substack.com)

Article summary

The article discusses the concept of decibels (dB) and how they are used to measure ratios of quantities, such as sound pressure or power. The author argues that the decibel is a flawed unit because it describes a change in magnitude rather than a fixed quantity, and its meaning can be unclear without context. The article also explores the history and development of the decibel, including its relationship to the bel and the use of prefixes like dBm. The author suggests that the use of decibels can be confusing and inconsistent, particularly when used as a standalone unit without a clear reference point.

Main themes

• decibel definition
• measurement of sound levels
• logarithmic perception
• audio engineering
• unit consistency
• practical applications
• alternative units

What commenters say

• The decibel is a useful unit for measuring ratios of quantities, but its meaning can be unclear without context.
• The use of decibels is flawed because it describes a change in magnitude rather than a fixed quantity.
• Human perception of loudness is logarithmic, which is why decibels are used to measure sound levels.
• A 3dB increase in power is not equivalent to a doubling of perceived loudness, but rather a doubling of power.
• The decibel is a necessary unit in certain fields, such as audio engineering, because it allows for easy calculation of successive applications of gain or attenuation.
• The definition of decibels is inconsistent and can be confusing, particularly when used in different contexts or with different prefixes.
• The use of decibels can be defended as a practical and useful unit, despite its flaws, because it has become an established standard in many fields.
• Alternative units, such as sones or phons, may be more intuitive or useful for measuring loudness or sound levels.