Find out if LUFs or decibels be used for sound measurement of loudness in your podcast and learn the difference between the two forms of measurement
Short version for podcast producers, editors, and/or mixers
The TL;DR for those looking to know if they should use LUFS or decibels to measure loudness is… Use LUFS over decibels when adjusting audio loudness and for podcasts set your loudness to -16 LUFS. LUFS > decibels.
What exactly is a decibel?
A decibel (abbreviated dB) is the unit of measurement for the intensity of sound. At a frequency of 1 KHz, the smallest sound that human ears can detect has an objective volume of 0 dB. However, a decibel is not an absolute level or unit of sound; it represents the amount of air pressure that the sound creates. As it grows in volume, sound displaces more and more air pressure and that is what people characterize as loudness. The decibel scale quantifies the different levels of sound in a more meaningful, manageable, and measurable way.
What does LUFS even stand for and what does it measure?
The LUFS meter (Loudness Unit Full Scale) measures the perceived loudness of audio material. This standard is also referred to some as LUFS (Loudness K-weighted Full Scale). Despite the difference in names, these two are exactly alike as they describe the same phenomenon of measuring loudness. LUFS is a newer standard for measuring loudness and is considered as the most accurate.
In practical applications, LUs are equal to decibels. Amplifying audio by 2dB is the same as raising its volume by 2 Loudness Units. The same applies for LUFS units.
How do LUFS and decibels differ?
Loudness Units differ from decibels in a number of ways. First, a decibel simply quantifies the amount of air pressure displaced by a sound. A Loudness Unit upholds the consistency of the resulting volume from the audio. Second, a decibel uses standard air pressure as a reference point in measuring the intensity of sound. A Loudness Unit does not require a reference to measure the same loudness.
How are decibels measured?
The relationship between sound intensity that hits the eardrums and its perceived loudness is not linear. The decibel scale is thus logarithmic in nature and uses the standard intensity of 1×10–12 as a reference point. This scale reports all audio intensities as logarithmic ratios relative to the reference intensity.
How is Loudness Unit Full Scale measured?
Most normalization tools measure only at the peak points of audio. LUFS takes into account the average loudness of podcasts over an extended period of time. Therefore, an audio file with loud, momentary peaks will have a consistent volume within a LUFS algorithm as they do not affect the long-term average. With any other standard normalizer, the same audio will shift in volume each time the peak reaches a certain level. Momentary readings in LUFS are adjusted according to the Fletcher-Muson Curve. This standard applies a high-frequency boost to inconsistent audios, making them more suitable to human ears.
Why should professional quality podcasts use LUFS over decimals when adjusting loudness?
In the past, a listener would have to adjust their volume depending on whether music was playing or the host was talking. LUFS fixed this problem by permitting podcast sound normalization. The LU does not normalize audio to its peak levels; rather, this measure normalizes sound only up to a certain volume of loudness as perceived by human ears. If one is playing five podcasts consecutively, the LUFS standard ensures that they all have the same loudness. Professionally produced, mixed, and edited podcasts adjust to the standard measure of -16 LUFS vs. allowing an app or listening device to mangle the audio to try and adjust the loudness when it is too loud or not loud enough. This frees listeners to adjust their volumes based on their environmental fluctuations and not on the podcast audio changes. Those skilled in the art of audio mixing and mastering for podcast loudness prefers to use LUFS because it normalized all pieces of audio to the same loudness standard; a feature that is just not present in the decibel scale.
Now you know. LUFS, LUFS, LUFS > decibels.