When I worked as VP of Business Development for a large multi-brand audio manufacturer there was a man named Thomas Lund in my department. His area of focus was audio products intended for use in broadcast and studio production.
He is the first, and likely the last, person I believe would lead a resistance trying to topple a government organization for mistreating its people. However, with his own marching orders, Thomas pushed governments and standards organizations to change the way we produce audio by caring about the affect of loudness on our lives – both physically and mentally.
He regarded the un-regulated drive for music and entrainment producers to make their content louder than their competitors as a war that needed to stop.
He and his peers deserve accolades for success in this battle. Every person that has ever listened to music, TV shows or movies in the past decade has unknowingly appreciated the work done in the war on loudness. Although the war is still on-going, there are some fruits we can enjoy.
One of those fruits is that the focus on measuring loudness in the production of audio has started to correct the disastrous vocabulary that audio professionals have perpetuated.
Our Audio Vocabulary is Wrong?
Yup.
Growing up as an audio professional in the early nineties my audio vocabulary was so discombobulated you would have done better to learn audio from me by turning you ears off.
I, along with my fellow audio-term-illiterate audio professionals, were tossing around words like volume, level and loudness like they all meant the same thing and everything. It would be like using the words apple, oranges and bananas interchangeably to describe apple, oranges and bananas!
Learning and caring about loudness required me to choose my words more carefully. Not surprisingly, choosing the right words helped people around me understand the right message.
What is the wrong word?
Volume.
Don’t use the word volume. Avoid it as much as you can.
Volume has been the most misused audio term and therefore trying to correct its use is a battle not worth fighting. The problem with using the word “volume” is that it is associated strongly with a “volume control” as well as what it is controlling, for example, “turning up the volume.” But what are you turning up? Depending on where that control exists — in your DAW, on an Amp, or an input to a compressor – what you’re changing could be measured in different ways.
What are the right words?
Loudness & level are the first words to get know.
Level is a measure of power of signal. That power may be in volts, pressure or, in a roundabout way, bits.
Loudness is our perception of sound as being quiet or loud. It can also be measured by factoring in how we hear sound over time.
There are many levels
Our standards for measuring level are similar to measuring other phenomena like fluid, light, etc: We tend to measure a given point in time; we measure logarithmically; and we have some sort of reference point.
When sound is produced by a voice in the air, we can measure the pressure or force of the air. We express this as dB SPL (Sound Pressure Level)
When we convert that sound pressure to an electrical signal using a microphone we can measure the voltage of that electrical signal. We express this as dBV or dBu.
When we convert that electrical signal to digital using an audio interface we can measure the level of the signal in terms of how far away it is from the the maximum digital level determined by the bit depth (8, 16, 24, 32 bits). We express this is dBFS (FS is for full scale).
We use dB (decibel) in all these measurements because the measurements are all ratios against a reference.
- The reference for dB SPLs is normal air pressure – 0 dB SPL
- The reference for dBV’s is 1 volt – 0 dBV.
- The reference for dBFS is the maximum digital level – 0 dBFS
Well then, what is loudness?
Loudness is how we perceive sound from quiet to loud. It’s a characteristic of sound along with frequency, pressure, etc.
Saying something is quiet or loud is not new. I’m sure a parent saying to a child, “be quiet” may actually be the first words spoken in any a language!
What has changed is that we now recognize that even though we measured the level of sound accurately, we had a practical flaw. Unlike a measurement device, humans perceive sound differently at different pitches and over time.
This Concert is Too Loud!
Let’s pretend you lived in apartment with a difficult-to-get-asleep baby before #loudnesswar started.
The summer outdoor concert in the park beside your place is getting too loud.
You storm down to the park, babe in arms, and march up to the sound engineer and say, “You’ve got to turn this down. It’s way too loud!”.
The mildly annoyed sound engineer says, “I was told by the park authority that this concert can’t exceed 110 dB SPL. Look at my SPL – it’s not exceeding 110 dB SPL.”
You say to yourself, “Crap! The sound engineer was following a guideline and using a real measurement. But it’s still too loud!”
It turns out SPL on it’s own is not the best measurement to determine if the concert in the park is too loud.
Not All Frequencies are Equal
Our brain does not perceive the loudness of all frequencies in the same way. For example, we perceive sounds that contribute to the intelligibility of speech as louder than other frequencies. So we have a peak in response around 2,500 Hz. We also tend to perceive frequencies below 100Hz as quieter.
Sometimes we measure SPL by applying what is call “K-weighting”. This weighting compensates for how we perceive various frequencies.
Time Matters
Our brain’s perception of loudness is also affected by time. A single one-second scream of 120 dB SPL is less likely to annoy a parent than one 30-second rage fest at 110 dB SPL.
Today we can measure loudness
So, our models for measuring loudness factor in the weighting of human hearing as well as the time exposed to sound.
K-weighting and time combine to form a loudness measure called LUFS (sometimes called LKFS).
Thanks to work by audio pioneers like Thomas Lund and his peers, measurements of loudness ensure concerts in the park aren’t too loud and also ensure every YouTube video, music stream or TV commercial can be experienced without needing to constantly turn the level up or down.
Thanks Thomas:-)
Kevin Alexander is CEO and co-founder of Singdaptive, bringing his past experience as CEO of the singing technology company TC-Helicon, as well as live sound, recording and love of music. Recently, he has been a university instructor in Multimedia Learning and is helping to envision an exciting future with technology at the research firm Kinsol.io
