That is true. I was thinking of it because of the comments on Dynamic Range Expanders, and I wanted to give an example of processing to reduce loudness and expand for a different purpose.
Range expanders can help if you are listening to loudness wars recordings and have no alternative master without the compression.
There is compression and expansion inherent in RIAA equalization. But it’s not uniform across the frequency range. Based on the graph above, one end of the frequency range (the bass) is being compressed, while the other end (treble) is expanded during recording. And the process is then reversed on playback with a phono preamp (really a reverse EQ) to restore the recording’s original tonal balance.
I don’t know enough about the recording process to be sure that’s actually how it works. But that’s the implication of what the graph is showing.
DRC does not have to be uniform across all frequencies. But if we’re talking about it in the most generic sense, that would usually be the implication or assumption… That the high, low, and also the midrange frequencies are all being compressed in more or less the same way.
I think it’s also important for people to understand the difference between a recording that is limited in its bandwith (ie the overall range of frequencies), and limited or compressed in its dynamic range. Because these are not the same things. And I often confused the two when I first started to learn and read more about audio.
Hi everyone, I’m new to the forum so greetings to all!
As an audio professional who has experience as a recording engineer in a commercial studio and mixing/mastering, I’ll offer some information that will hopefully help with understanding what compression is, as well as maybe dispel misunderstandings/myths about it.
To answer the OP’s question: Compression by definition in an audio sense is the reduction of the difference in amplitude between the loudest and quietest part of a signal.
Now in my observation of the headphone community, the term ‘compression’ can mean a variety of things (as astutely pointed out by @generic ). Power compression in loudspeakers reaching their limits of driver excursion and the resultant thermal issues is not an issue that headphone drivers pushing so little air are going to exhibit.
The most common use of the term ‘compression’ seems to be to describe the perception of the listener of a certain headphone failing to faithfully reproduce the differences in loud and quiet parts of a song.
Example doesn’t require uniform.
While the loudness wars AND the AM radio trick used a full frequency compression, early Dolby noise reduction for tapes (both the original Dolby A and the later consumer Dolby B) focused on specific frequencies.
Welcome aboard, JDog. Your thoughtful reply is appreciated.
I wonder if you have any speculation as to why some headphones might be producing this effect for listeners… or at least the perception of it?
I’m still sort of stumped on this one, and what might be causing it.
So do you think that folks are just using this term to describe a part of the frequency range that is more depressed (perceptually) in level than other parts in their headphones?
I’m not sure why you are stumped. It can mean many things and have various causes. Sometimes real, as with advertisements that boost average volume by cutting the peaks, or perceptual, or an electrical / mechanical artifact.
You’re very welcome ADU!
So many factors to consider here when it comes to this.
Firstly, I mention the ‘perception’ of compression because in general, the average listener (even the average seasoned hi-fi listener) is an untrained listener. By untrained, I am referring to an unfamiliarity with what the original source material of the music they are listening to sounded like before playback through their gear and headphones. So when someone says this and that headphone sounds compressed, one has to ask if it is indeed the headphone producing that artefact, or if the music sounded that way in the first place, by design or not! Simply put: critique without perspective. Most people have never heard what compression actually sounds like or how much it is deployed in the music we all listen to and enjoy. This is true for almost all genres as well.
Secondly, if the compression effect is indeed coming from the headphone, this will likely have to do with some drawback of the driver design. I’ll leave the electrical engineers to do the math, but all driver designs are a collection of compromises that have to be balanced in order to meet the designer’s criteria. The ability of a driver to reproduce transient information will have a lot to do with variables like the mass of the diaphragm, magnetic flux of the motor (voice coil and magnet), damping etc. Usually if a driver is light and fast, it’s transient reproduction improves and the difference between the peaks of the transients and the low level information increases and is perceived as dynamic.
There is always a convergence of so many factors when listening for pleasure!
Good observations, JDog.
Regarding headphone drivers, the headphone amp plays a more significgant part controlling the driver than I realized. Comparing the differences between a Kludge OTL headphone amp and a Aurouasound HEADA headphone amp, the tube amp has more midrange bloom than the HEADA. With some recordings, it’s a pleasent effect. With other recordings, it can be a bit too much.
The biggest advantage the HEADA has over the tube amp is that when listening to a symphony recorded live in a hall, the effects of the hall can be clearly heard with the HEADA, but not so much with the tube setup. The bass is also tighter with the HEADA. The HEADA has amazing upper midrange and treble playback, almost tube like.
Just picked up a Schiit Mjolnir headphone amp, and very much looking forward to trying it out.
I’ve been amazed with how much more revealing headphone listening can be with recordings over speakers. They really expose the strengths and shortfalls with recording quality more so than loudspeakers.
Right, generic. I get this.
Most of the music I listen to (e.g. pop, classic & alt-rock, r&b, disco, chalga…) is generally compressed and/or limited in some way. Often quite heavily. So I’m very used to that type sound.
Sometimes it can be well done, and sometimes not. More often I’d say its not very well-done in the music I listen to. And can be particularly obnoxious in some K and J-pop tracks, for example.
So yes, DRC can be quite common in recordings. And I agree it can also occur in your other gear. Quite easily in fact. What I’m still not understanding is why some experienced listeners and reviewers are describing this type of effect as coming from their headphones.
I assume @Resolve knows the difference between a recording that is highly compressed, and one which is not. And that he is not making the mistake of confusing the compression in a song he might be listening to with the “compression” he’s hearing from a pair a headphones. I’m still stumped by what he’s referring to on this though.
This is not a term I’d generally use to describe the sound quality of a headphone. Even subjectively.
Sometimes that can be good, and sometimes not so much. I don’t think one technology is necessarily superior to the other though. They each have different strengths.
I’ve played the same tracks on different drivers and reached the same conclusion. Take a look at my Utopia review on this site – especially row 4 of the comparison table at the end. Per extensive back-to-back comparisons, I heard only two levels of volume (limited dynamic range) from the HD-600 but much more dynamic range from Focal’s products. This may result from driver materials and construction (e.g., plastic dampening vs. precise metal).
Before I wrote that review I bought a Schiit Magni 3 (not the 3+) for my HD-600. To my ears the amp simulated recording compression with every complex, noisy, and distorted rock track I tried. The Magni 3 had terrible treble spray to my ears, so every time it was supposed to go loud my perception went upside down – it sounded softer during loud passages. That was purely from the amp.
Sample test tracks: early Pixies albums, Nirvana’s Smell’s Like Teen Spirit, Sleigh Bells Treats, etc.
Wait wait … the solution is obvious. Develop an obsession for nice acoustic jazz, classical, chamber, baroque and even Indian classical.
From K-Pop search for V and his tiny desk session.
Absolutely. I’ve managed to put together a very good loudspeaker system, and it can be very engaging with symphonic music.
It does cost more $$$ to get a loudspeaker setup to sound great as opposed to a headphone setup.
You can bet 99% of any music genres you listed have limiting and compression applied to get it to sound competitive.
I’ll like to point out that compression and limiting are not only used out of utility but almost more so an artistic choice to shape sounds and get elements to sit better in a mix.
So when you say compression and limiting has been done poorly on most tracks, I have to ask what about it you didn’t like and what led you to think it was poorly applied compression/limiting?
When it is over-used, especially to increase loudness to sound better on poorer sounding audio gear… That’s really it in a nutshell. Some use the term “brickwalling” to describe the worst examples of this. And in a way, it just defeats the whole purpose of buying better audio gear. Because you just end up having to turn it down to make the content listenable.
Sometimes the brickwalling is so bad that it also results in clipping and distortion in the loudest passages in a recording, which is just awful to listen to!
This kind of authoring (I won’t call it “mastering”, because that would be an insult) is unfortunately still very de rigueur in many of the genres I listen to. And its because many consumers of this content are still listening to it on inferior gear, like the speakers on their laptops, TVs, cell phones, desktops, car radios, or stereos in a box. Gear with often very limited volume/dynamic range, without distorting.
I could just listen to the beautiful high dynamic range recordings of jazz and chamber music, like pennstac suggested. And I do like some jazz and classical compositions (Prokofiev is a favorite). That’s not really what I enjoy listening to most of the time though. 
Country is another genre I sometimes listen to where the compression for loudness is often taken to unpleasant extremes. I think they just like it loud though!
Well, there is real country music. Like Flatt and Scrugs, or Theodore Bikel - you choose the country.
But you did say K-pop, so of course BTS. I hope you have heard how good V is when not compressed
Pretty good! I assume you’re a fan of the Coke Studio sessions as well.
Also consider the age and listening history of the creator. I’ve noticed that some cranked up the compression with later albums (e.g., Muse with Simulation Theory, Red Hot Chili Peppers with Californication). Other performers have experienced hearing loss (e.g., Sting, Neil Young, Pete Townsend, and many more), so they either sign off on garbage that they can hear or allow others to decide. Their aging associates may also have poor hearing. Finally, most 1980s rock/pop was affected by graphic equalizers (set in a “V” shape), and the treble boost did not help the hearing of anyone.
In the context of headphones, “compression” refers to a technique that reduces the dynamic range of an audio signal, meaning it makes the loudest parts quieter and the quietest parts louder, effectively evening out the overall volume. This is different from the term “compression” in digital audio files, where it refers to reducing file size.