If you have no idea what mastering is and why it matters, the tl;dr version: mastering makes music sound better. Some really clever audio geeks sharpen the dull parts, make the beats punchier, and usually raise the volume. A bunch of processes with names like "equalization", "dynamic compression", and "limiting" are involved and have been joined by newer trendy friends like "transient design". Mainstream awareness of mastering was greatly helped by the loudness wars, which goes to show too much of a good thing… is still too much.
Like I said, it takes smart people to do mastering well. For decades, it was a black art because the mastering engineer was usually a different person than the musician. An artist in his/her (female mastering engineers, like DJs, are rare) own right, perhaps less appreciated.
Computer world
Now, with the omnipresence of computer recording technology, even folk musicians with acoustic guitars dabble with mastering. Which is good for all involved because musicians and listeners have a firsthand understanding of why it's so important, and brilliant mastering engineers can continue touting "Leave it to the pros!" while at the same time offering unique value (like vast experience which many musicians don't have time for, and an outside-but-intuitive opinion on "how this should sound").
Like how many careers have been remixed as new kinds of knowledge work gain prominence, many musicians, especially electronic ones (as they're predisposed to the tech-geekery), want to have more control over their end product. This isn't really different from marketing music yourself.
Master controller
As a result, within your audio workstation, you can have a "mastering chain" — a set of devices to polish your work — setup at the end. Some musicians like myself actually master while they mix (e.g., adjust track volumes and panning). In odd-but-increasingly-common cases like mine, there's no clear distinction between "mixing" and "mastering". This sounds incredibly haphazard to "purists" who whimper when change bitchslaps them.
That's OK. Purists aren't adventurous, but you can be. You can always hire a veteran mastering engineer if doing it yourself isn't your bag.
The crippled masters
Let me tell you about where a disability set me free: I have hyperacusis, which is different than tinnitus (which I also have). This means I don't hear music as most people do, and my perception of the frequency range is messed up. Sometimes, the world around me sounds muffled and underwater. It's a chronic pain because I repeatedly have to ask my wife and other people to repeat what they're saying.
As a result, like how I've developed automation across the rest of my life, I've created a mastering system that effectively masters my tracks in a typical 5-20 seconds. It isn't AI, it isn't highly technical, it's simply customized for how I work and play in the studio. From feedback I'm getting for my Dream Journal (because as nice as "trust your ears" sounds, due to my perception I can't comply), I'm getting superb results. Mastering helps the melodies shine. I'd wager 95% of the results in less than 5% of the time. How's that for Pareto principle?
And yet, I feel conflicted. I miss having better hearing, but regrets ain't gonna change that, so I soldier on. Will I share my mastering method? I heart sharing a lot of knowledge. It's a future consideration for when my means has evolved to where it's good and stable enough for others to use. (I'd feel dirty in a bad way supporting it otherwise.) In addition, I have to feel rippleshock that another musician could really benefit from adapting how I do it because we're bonded, likeminded, resonate on the same wavelength, etc.
Even more importantly, there's the whole backstory behind how I got here after my first mastering experiments over a decade ago, and that's fundamental: I wouldn't tell just a part of the tale now, would I?
But if I had one line of advice: buy Bias Repli-Q. It's like a Braille translator for the hearing-impaired. They don't list that as a feature, but like how avatars can be our free bodies roaming in cyberspace, Repli-Q is my virtual ears. I even sent them a testimonial.
You braggart!
No. My point here is not to get all "DINOBOTS SUPERIOR". Quite the contrary. It's to show that yeah, even with physical defects, you can make awesome records (not literal records, but you get my drift). Sometimes, injuries block part of your life and you get used to them, then consider other possibilities. Other people can see the world in ways you can't, but the reverse is true. I've observe this from blind jazz trombonists to the nice people who told me, "Beethoven made great music when he was deaf!" and I said, "I'm not a genius like him."
But, you don't have to be Beethoven.
Just be you, making art that no one else does. That's why you do.
