Hi-Resolution Audio Explained
You may have seen the term Hi-Resolution or Hi-Definition audio thrown around here or there, but compared to its visual counterpart, it still remains much of an enigma to the mass market.
Today, we’ll be looking at exactly what Hi-resolution is and whether or not it truly has any meaning or if it’s simply another buzzword in the audio-visual industry that we’ve all come to know and love.
Considering we’ve been told to believe that anything “HD” is of superior quality by manufacturers, it would be prudent to believe that anything but is satisfactory in this day and age. So are we really being short-changed when provided with anything less than truly “Hi-resolution”?
What exactly is Hi-Resolution Audio?
While there is no industry-wide agreed upon threshold to exactly what constitutes as Hi-Resolution audio, the informal agreeable usage of this term dates back to the days of the trusty old Compact Disk. Anything that can match or go beyond what CD audio is capable of, 44 kHz or higher, and a bit-depth of 16 or higher can be considered Hi-resolution with most hi-res offerings aiming for 96kHz or 196kHz and a 24bit bit-depth.
But what does that mean exactly?
I’m going to break this down into two sections. First of all, we have Frequency. All frequencies are measured in Hertz (Hz) and KiloHertz (kHz) and define the range of audio we, as humans, can hear. Lower bass line notes are down at the bottom of the Hertz scale and high pitched sounds are towards the top. It’s generally agreed upon that humans can only hear between the 20Hz-20kHz range.
But if that’s the case, why do we need audio tracks with sample rates above 20kHz?
This is where things get a little technical and I’ll avoid going into too much detail here to ensure things remain straightforward and understandable without falling down the rabbit hole on how audio processing works.
Something called the Nyquist theorem dictates that if you wish to capture analog audio i.e a studio recording and convert that into a digital format then it needs to be done at twice the frequency. So recording an analog signal at 40kHz and converting that into something digital will lead the final digital product to be 20kHz.
There are many nuances to this theorem, but this is the basic gist of it. If you want to learn more about this theorem, this video does a pretty awesome job of summarizing it. Be warned though, it does get pretty technical!
So that’s frequency, how about Bit-Depth?
Bit-depth, not to be confused with bit-rate which I’ll explain later, directly affects the dynamic range of a track. Dynamic range defines how the soft and harsh a sounds that are being recorded can be reproduced and also affects the volume of the recording.
For example, a top hat on a drum kit is a very harsh loud sound, but if the bit-depth isn’t broad enough to pick up on its full range, it will become muted and distorted.
Again, there are many nuances to what exactly bit-depth can affect, but in its simplest form, it affects how well the loudest and quietest sounds translate into real life audio when being heard back to you.
Let’s put it all together
So armed with this information, if we were to look at this in a real-life example it can be looked at in this way:
If I were to play a high note on my flute, it would produce a rather loud, high pitched sound. If we do not record it at the correct frequency, the reproduction runs the risk of sounding lower pitched than it actually is. This high note is also particularly sharp and loud. If we don’t record it with the correct bit depth, it won’t carry the same loud impact as originally intended and it may not be reproduced in the same crisp “ear-piercing” way.
This concludes how we capture audio in hi-resolution manor, but that’s just one piece to the equation. Next, we’ll be looking at how that captured audio is played back.
Playing Back Audio at a Higher Quality
The next piece of the puzzle is bit-rate. Again, without going into too much detail, this measurement essentially determines how many “bits” of data per second can be played back. The more “bits” the higher the quality of the audio as it adds extra pieces of data into the track. Naturally, the more bits, the larger the file size is.
Generally speaking, an uncompressed track will take up a very large amount of space. 3 minutes of uncompressed audio, with a frequency of 44kHz and a 16 bit-depth will take up around 30 MB of storage space. If you only have 8GB of storage, that means you’d only have room for around 250 tracks – not a lot if you happen to have an eclectic taste in music like me!
This is where compression comes in. By now you’ve probably heard of MP3, the go-to compression format designed to make audio data slightly more manageable by reducing its size.
The way it does this, however, is by a method called lossy compression. Data is intentionally lost to reduce the file size.
That’s not to say it’s just randomly picking out data from the track and deleting it at will.
The compression method picks out, what is considered to be, dead space and removes parts of the audio which it deems unnecessary to the overall track. This article explains in deeper detail exactly how it does this.
Naturally, however, this is going to lead to degradation of the track. The level which that may be is an eternal debate for audio purists. While some may say they notice it more than others, there’s no denying that something has been lost in this process. That once uncompressed track which clocked in at 30MB would only be 7MB while compressed as an MP3 track in its largest form.
There are other options available, however, for audio compression which don’t have quite such a dramatic effect. FLAC, or Free Lossless Audio Codec is a method of compression which essentially compresses the size down to around 60-70% of its original size, but using your hardware and CPU, un-compresses that file when you listen back to it, essentially leading to a truly lossless listening experience. You’ll still have a larger than average file on hand, but it’s what many would consider a purer experience.
The limitation to these formats which I’ve touched on above is also that your device will need to be able to work with them. Not every device is compatible with every single format, with hardware maker such as Apple, often work with their own proprietary formats.
Getting your hands on hi-resolution audio files
Sadly, it doesn’t come cheap. There are a number of options for downloading these tracks but I’m willing to bet you’ve never heard of most of them. Looking at one of the biggest marketplaces, hdtracks.com, you can probably see there’s little investment going into marketing these tracks. That’s not even mentioning the price.
Lately, however, there is one more major player in the game. Streaming services.
For truly lossless streaming, you’ll need to have an incredibly fast and stable connection and a lot of data allowance. Considering most people would want to do this on their cell phones over cellular data connections, it could easily suck up an entire months data plan in just a few songs. Nevertheless, companies have slowly but surely began to adopt this, albeit at a premium.
Probably most notably, Tidal began offering Hi-Resolution audio streaming at the steep price of around $20/month back in 2014.
Many have struggled to find the same traction that Tidal have which could perhaps signal a lack of demand. While Apple remains secretive of their lossless streaming plans, if any, Spotify began Beta testing their solution in recent years. Although, this can be taken with a grain of salt until officially announced considering Spotify, by their own admission, are notorious for abandoning Beta projects before they make release.
Tidal’s Pricing Structure at the time of writing this article
What do I need to listen to Hi-Resolution Audio?
First of all, you’ll need compatible software and hardware. Most modern computers, cell phones and tablets come with software capable of playing Hi-resolution audio. If it isn’t pre-installed on your device then there are a multitude of apps and programs available to help you playback files. It all depends on which file you are using. While FLAC is the most commonly known format, a variety of lossless file formats exist.
Hardware wise, the barrier to entry is very low, with some caveats. If you intend to connect to your headphones or speakers via an aux cable, you’ll be relying on your devices internal Digital to Analogue Converter (DAC) as this needs to be done as soon as the data leaves the phone via the Aux jack as from this point on, the audio becomes an analogue signal.
This is the thing that will convert your digital file into an analog sound which will come out of your headphones and speakers. Most phones and tablets will get the job done, however, the sound quality may deteriorate during this process and overall weren’t designed to produce audio for larger speakers and other audio equipment.
If you do have a phone that is able to connect with your chosen listening hardware via USB, then you’ll get much better results this way if that device has a built-in DAC. Car stereos for example, often have much higher quality converters built in than smaller iPhone and Android phones meaning they can provide a much better solution for converting digital audio.
If you’re planning on connecting your device to an external speaker then a true audiophile should consider investing in a high-quality external DAC which will result in a truly lossless audio experience if no USB option is available.
Why Isn’t It Seen More Often?
We’ve already touched on a number of restrictions to hi-resolution audio, but by far, the most inhibitive is the pure amount of storage space needed to store lossless files compared to something that has been compressed. While we are in an age of ever-increasing storage space, there is an array of other apps and media player for our precious megabytes of storage space.
We’ve all come to know and love, or at least ignore the drawbacks of, lossy file formats and with the majority of people simply just not caring enough about hi-resolution audio for it to ever catch on, we’re left with only true audio enthusiasts keeping the buzz alive.
The fact is though, no matter how much audio enthusiasts will argue over this, the layman is very unlikely to be able to tell the difference unless they are using truly high-end audio equipment. You most certainly aren’t going to be able to tell the difference while the hum of the bus chugs along in the background during your daily commute.
With all this considered, it’s only natural that we’ve decided to stick with our lossy formats.
Summary & Thoughts
While I personally have been in situations where I’ve experienced the true difference between regular and hi-resolution audio, the occasions have been far and few between, at best.
That said, there are a handful of options on the market at the moment which are completely overkilling in terms of hardware. With humans only being able to hear frequencies up to 20kHz, there seems to be little reason to go above that, yet some still strive for this.
Some will argue that it has its benefits beyond simply what you can hear, however, there’s little research in this field right now to really substantiate any of these claims.
In terms of lossless audio formats, while high-resolution audio is certainly not going anywhere soon, it’s highly unlikely it will ever come into mainstream success in the same way that the MP3 file format did anytime soon. With lackluster interest from the general public and some critical drawbacks, this is something that will remain one for true audiophiles only.