Why do certain songs sound louder than others even when they’re played at the same volume?
In: Technology
Its the way it is produced. Imagine, different people speaking at a mic in an auditorium. Some may speak louder than others. Even though speaker volume is unchanged you can make out the difference.
While post production some may amplify a bit.
There’s an audio technique called levelling, where the overall average volume can be changed. Some CDs have different levels depending on the production values, and sometimes because the range of volumes in the music (loud vs. soft), more common in orchestral pieces. You’ll see levelling used on radio and TV stations, they use it to keep the audio low so that they can blare commercial sound, used to be a common tactic.
FYI some PC audio applications like snackamp can take your audio library and “auto-level” them for you, do you don’t have to mess with the volume controls all the time.
They’re probably not actually at the same volume. If we record you whispering to me, and me yelling at you, and then play them both back at 100% volume, it doesn’t change the fact that we recorded you doing something quiet and me doing something loud – the playback volume may be the same, but the source volume is different.
One thing to blame is the [Loudness War](https://en.wikipedia.org/wiki/Loudness_war?wprov=sfti1), where producers mastered their albums to be louder on the radio than other songs.
Imagine two recordings of the same song: in the first, the singer was sitting right in front of the microphone; in the second, the singer stood 20 feet away from the microphone.
If played back at the same volume, which recording do you think would be louder?
The point is that the producer of any music has a lot of influence over how “loud” music will sound when you replay it. They can influence loudness of the recording you replay in any number of ways. Your volume setting has no bearing on their recording techniques or post-recording changes (usually with software) to the recording before it was delivered to you.
* If one song has loud peaks every now and then, and another song has loud peaks all the time, the second song will seem louder even though the peaks of each song are the same level.
* Producers use a technique called “audio compression” to do this.
* Also TV and Radio stations use it too. They use it to make songs and commercials easier to hear in noisy environments.
[Perception of Loudness](http://www.physics.mcgill.ca/~guymoore/ph224/notes/lecture13.pdf)
The frequency of a sound impacts its perceived loudness. Source: audiologist
Volume is not the same as loudness. There’s several ways to measure sound levels, peak measurements deal with the loudest points, and then there are special algorithms that measure average levels, which are much more accurate at measuring loudness. You can have the same volume playing two different source materials which have been processed differently, and you’ll hear them having different loudness, despite the volume in your amplifiers being the same.
2 main things. 1, the amount of limiting/compression. Compression (and limiting, which is the same as compression, just more extreme) is essentially done by making the loud parts of music quiet, so you can make the quiet parts loud. That is, there is a defined peak loudness that a sound can have. If we take the loudest parts of the sound and smash them down, we can raise the overall loudness of the sound. Imagine recording a gunshot. The very first few milliseconds of the recorded sound are massive, but the rest of the sound (99% of the sound) is much smaller. If we take those first few milliseconds and squish them down, we can raise the entire sound wave.
Next: Perceived loudness vs actual loudness. By limiting the peaks, we’re bringing up the rest of the signal. Even though we have a defined peak (in digital audio there are only so many bits in a sample), we can make it sound louder. If you look at a waveform of a song that hasn’t been limited, it has lots of peaks and troughs of varying magnitudes. If you look at the waveform of a mastered (heavily limited) song, it looks like a sausage. The songs are both the same loudness, but the squished one sounds louder.
Hope this helps. Source: multiple Grammy nominated recording engineer.
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