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- A simple test can see how well you can recognize lossy formats using your own music choices
- Beyond a certain point most people can't easily tell the difference
- High-quality lossless is still the most future-proof format
With music, how good is good enough? When you're listening to digital music, what you hear depends on the original master, the file format and most of all, whether it's lossy — reducing the sound quality to reduce file sizes — or lossless, which is pristine and perfect. If you're serious about sound, lossless is going to defeat lossless every time.
Right?
Perhaps not.
On the r/audiophile subreddit, a user called vlad1m1r has shared a tool that tests how well you can differentiate different quality levels and formats. Can you tell the difference between a lossless FLAC or WAV and a 320kbps MP3, even if it's music you listen to all the time and you know inside out?
According to Apple Music exec Oliver Schusser, most people can't. Speaking to Billboard, he said that "honestly, if we did an anonymous blind test on just an iPhone with headphones… I can tell you most fans wouldn’t be able to tell the difference."
Is he right? It turns out there's an easy way to find out. Vlad1m1r's Flactest runs in your browser and enables you to drag a FLAC, WAV or AIFF file onto the app, at which point it will re-encode it to different MP3 bitrates and play them to you without revealing which one is which.
And at the risk of sounding clickbaity, the results may surprise you. They certainly surprised vlad1m1r, who struggled to tell the difference between uncompressed FLAC and high-bitrate MP3.
Redditors have been having fun with this, and I thought I'd join in. I've got a very nice, Hi-Res Audio-friendly, setup. Are my headphones, speakers and ears good enough to spot what are often very subtle differences?
The trouble with testing
One of the problems of listening tests is that you can't always be sure you're listening to the same version when you're comparing different formats and bitrates. Some releases, especially of legacy artists, have been released multiple times and in some cases remastered, and that's likely to change the sound more than a minor difference in the encoding rate.
The source quality isn't the only factor that'll affect what you hear, of course. The speakers you're using, their placement and the acoustic qualities of your room make a difference, as will the kind of headphones you're listening on, the DAC you have and the volume level you're playing the music at. Those will all shape the sound, too.
Flactest solves a lot of that for testing purposes because all of those things stay constant. You provide a single original and it then re-encodes it in multiple resolutions of MP3 via the same LAME codec, as well as playing your untouched original. What that means is you get consistency: you're listening to the same song from the same source on the same hardware and software as you switch between the five mystery formats it serves up.
It's worth noting that there's another factor at play here, and it will apply to everyone who is no longer a teenager: age. From early adulthood we start losing the top end of our hearing, and that means a 50-something like me won't hear the same highs that I could easily discern at 15. So, if encoding changes are making a difference at the very top frequencies, which is where a lot of digital artefacts tend to live in compressed MP3s, I may not be able to hear much difference.
Sheer FLAC attack
I listened to multiple songs in two ways: on my large Adam studio monitors through an SSL 2 audio interface, and on BeyerDynamic DT990 Pro open-back headphones via an iFi desktop DAC.
My source files were 44.1kHz WAV and 16-bit/44.1 and 24-bit/96kHz FLAC, with songs I've listened to for years — Radiohead, U2, Talk Talk and so on — as well as music I've made myself on my Mac.
The low-bitrate MP3s were easy to spot because they sound atrocious, as if they're being played in the room next door by someone with a really bad hi-fi system. At 16kbps or 64kbps the MP3 compression is really obvious, and there's a noticeable step up in quality when you move to 320kbps on busier tracks where there's a lot going on. The tells are fizzy distorted guitars and acoustic instruments, especially cymbals and hi-hats that get noticeably "splashy" as you reduce the bitrate.
But after 128kbps it got tricky for me. Time and again I often couldn't differentiate between the 320kbps MP3s and the lossless originals.
Perhaps the trick to discerning the differences is to listen to the same music over and over again. When I ran the tests using my own music — songs I'm currently mixing — I got perfect scores. That makes sense, because I've been obsessing over tiny details in those tracks, such as the fizz of a drum machine hi-hat and the punch of a bass guitar, and I've been listening to those things again and again as I try to perfect them. But that's a different kind of listening than when I'm listening for pleasure.
For me at least, the answer is clear: I can't tell the difference between the highest quality MP3 and the same song as a FLAC on my headphones or speaker setup. But that doesn't mean I won't in the future.
No loss
It's well known that with some exceptions, most of us can't hear the difference between a very-high-bitrate lossy file and a lossless one on everyday audio equipment. Once you hit 192kbps or higher it becomes much more about the quality of your components: your hi-fi, your amp, your speakers, your headphones.
However, if you run the tests and find you can't tell the difference between lossless and slightly lossy, that doesn't mean you should stick to encoding or buying everything as 320kbps MP3 or the equivalent AAC. High bitrate lossy compression is still lossy, and once musical information is removed you can't get it back.
Upsampling can do a best-guess with impressive results, but it's still only a guess rather than the discarded data. So for long-term storage it's worth saving your digital music in the highest quality lossless format available to you, even if owning a high-end system isn't in your immediate future — because if you get better kit later you may regret not having better quality files.
I know from reviewing high-end headphones and from experiencing proper audiophile systems that cost way more than my car that with the right equipment you'll hear detail that lesser kit keeps buried in the mix.
And that's why I think it's wise to future-proof your digital library. You simply don't know what you'll be listening with in years to come. I thought I was pretty clever ripping CDs to 160kbps MP3 back in the iPod days, because I didn't have good enough hardware to need anything better — a choice I now regret as I've long since binned the original CDs. Today I'm on eBay buying many of them all over again.
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