Why are EBU Loudness Meters more sensitive to High Frequencies?
In this video we take a look at the K-Weighting Filter which is used in EBU Meters. It’s by far the most significant difference between an ordinary RMS Meter and an EBU Meter.
Why would you want to know about the shape of the K-Curve? Because it tells you what frequencies a Loudness Compensation Algorithm will be the most sensitive to. If you boost the Bass, your song will probably be turned down less than if you boost the Highs.
Many people think that loudness and volume are synonyms, since there’s usually a direct relationship between the two. However, loudness is subjective.
Since television viewers all over the world have complained about the loudness of commercials, the broadcaster’s International Telecommunications Union has proposed new standards to make loudness more measurable.
As opposed to volume units (VU) that are the standard for analog volume or decibels full scale (dBFS) that are the standard for digital volume, K-Weighting, expressed as LKFS (loudness K-Weighted full scale), has been proposed as a possible standard for loudness. Here, one loudness unit would equal one dB.
K-Weighting is based on perceived loudness. For example, recordings made with more presence due to good microphone placement, or recordings having more mid-range frequencies (the easiest for humans to hear), or those with more dynamic compression, so that the average volume is higher, even though the peak volume hasn’t increased, are perceived as louder than other recordings at the same volume levels.
To better measure loudness, a gate stops the meter when the level falls below -10 loudness units, so that those levels don’t pull down the average.
True-peak is an algorithm developed by TC Electronic, that measures not only the actual samples, but also the peaks between the samples. The proposed standard is to have peaks at -24 LKFS, using the gated meter with the True-Peak algorithm, so that the loudness playing field will be leveled for everyone.
