Bluetooth and Lossless Audio — Not The Enigma of our Age
For the better part of ten years, consumer streaming services like Spotify have been the mainstay of the masses when it comes to listening to music. Built on lossy formats like MP3, OGG and AAC consumers happily consumed their cassetteesque content. Cassetteesque? I will come back to that.
Recently, Apple released its lossless and HD audio options for its Apple Music service. This is nothing new. Tidal has been offering lossless music for years. As usual, the media narrative around this has been “but your headphones won’t sound any different because Bluetooth lacks the bandwidth to deliver lossless”.
Firstly, the beginners guide to lossless and lossy formats. What does it mean. If you’re anything like my wife you don’t care, you just want those 70’s disco vibes banging. Now I may get a bit technical here but I will attempt to keep it relatively easy.
There are two things to understand before diving into formats. How the audio is stored digitally. But how does a computer hear? Your computer hears through sampling. For sampling to occur, the computer needs to know “what to listen to every second” and how much space to allow those frequencies to be stored in. For CD audio, music is sampled 44,100 times a second and uses 16bits (2bytes) to store each sample per channel (left or right) and to capture each frequency, you have to sample it twice. This means that the humble CD could reproduce frequencies up to 22khz.
“Dude, 22khz, that’s crap, I have The Cars Heartbeat City in 24bit, 192khz, CD is soooo lame!”
If you were a dog or a toddler that would be true, except that as you get older your hearing deprecates and you hear less and less top-end (high frequencies), by the time you’re in your mid 40’s, you’ll be lucky to hear anything over 17khz let alone 22khz. I am sure some will argue with point, but we’ll argue HD Audio later.
Lossy formats take what is essentially that raw frequency and drop what the algorithm decides you can’t/wouldn't hear based on loudness. It’s called psychoacoustics. For example, if two frequencies are next to each other, but one is quieter than the other (masked by the louder), your brain will to an extent cancel it out by itself, lossy formats remove the frequency together. All this “cutting” results in a file that is smaller. Enter the MP3. I’m paraphrasing what goes on, but you get the drift. The lower the bitrate (120, 160, 192, 320kbit) the more audio data is dropped. This is the crux of the matter where the media has got it wrong, and I will come back to it.
Lossless formats take the raw audio and store it without dropping any of the frequency data, the downside is that these files can be 3–4 times larger which would be pushing the telco friendship 5 to 10 years ago.
Ok, now that we have that out of the way, let’s talk about how the media has it hopelessly wrong about lossless audio and the limitations of Bluetooth headphones. You see when your computer/device plays back a lossy music file, it unpacks it from its mp3 storage and plays it back as that raw audio, except you cant restore what has been dropped, that audio is then passed onto either Digital to Analog Converter (the chip that convert the 1’s and 0’s to a nice wave that your ears can hear) or it passes that audio onto the Bluetooth software/hardware on your device which compresses that audio again to allow it to “fit” over the air to your headphones — this is more lossy compression. Yuck. Two lots of compression.
For the older of us this is like taping a song off a CD to one of those old TDK D Cassettes and then giving that tape to your mate and he then makes a copy of or your cassette. His copy won’t be as good as yours. This is known in the business as “Generational Loss” — it’s a real thing — in the 80’s masters would be rolled off to one tape, this was the master, then masters would be copied from that, these are second-generation masters, and then the distribution channel would get copies of the second generation masters, these are third generation masters (It’s also why you should lament the UMG fire that destroyed thousands of 1st and second-generation masters) Whilst digitally a copy is a complete copy except where data gets dropped and this is what happens when your device plays lossy formats over Bluetooth and the results can be disastrous. It becomes Cassettesque!
So how do I get the best out of Bluetooth audio? Very simply, you need to reduce generational loss. This is why lossless audio from Tidal and Apple Music is a good thing for Bluetooth headphones. So while Bluetooth will compress the audio, depending on your Bluetooth gear, your ear will receive audio with less loss than a first generation MP3!
Don’t believe me? Go listen to Foreigners “Waiting for a girl like you”. In apple music, turn off lossless audio in settings. Listen to the ride cymbal at the very start. Now go close music, go back into music settings and enable lossless. Play it back again. Notice the shrill is gone from the ride.
Next, go listen to Split Enz — I Got You from True Colours, in the verses, listen to the snare. Now play it back in lossless. Notice the reverb plate tail is longer — trailing off to the left. It sounds longer not because the lossy format materially changed the mix, rather the lossy algorithm determined that at a certain point, those frequencies you didn’t need to hear and could be dropped. The chorus has a lot more going on, but the guitar feels more present.
OK. You starting to get it. Now go listen to Touch the Fire from Icehouse’s White Heat best of. Amazing song, somewhat muddy but there are some real treats to be heard. Around the start and first few phrases of the second verse, you get to hear the top end of the bass just poke its head through the mud, something lost normally — because it’s not so dominant, lossless formats drop it — the bulk of the data going to Iva’s great vocal.
In the words of Dr Julius Sumner Miller — Why is it so? Your Bluetooth is given more data to work with and can be more efficient.
So this is where the media is claiming your Bluetooth headphones don’t support lossless and that you won’t hear a difference. This is simply not true. Lossless music over Bluetooth reduced generational loss by giving your device more “data” to hear. In short, your brain is the best arbiter of what you should hear and while Bluetooth speakers cant deliver the full spectrum of lossless audio, it will certainly still sound better.
For those who care, I use Apple Airpod Pro’s with Apple Music. For critical listening, I use Beyer Dynamic DT100's.
