What's the best way to improve the sound of my voice?

Talk more.

Game walkthrough comedian Markiplier had his voice deepen considerably over the past couple years.

https://www.youtube.com/user/markiplierGAME

Don't concern yourself with his CONTENT; find a video from 2 or 3 years ago of his and listen to his VOICE...then listen to a recent video to hear just how much it has changed.

You obviously don't have two years. But merely by talking consistently will exercise your vocal cords and result in a deepened, stronger voice.

A vocal coach is a paid option.

Youtube searching for "how to improve my voice" came up with a bunch of video results.

Vocal habits are very difficult to change. That's something I'm more experienced with than you might guess, since I studied to become an opera singer when I was younger and also read a great deal on vocal pedagogy.

The problem really is that, in the early stages of coaching, an increased awareness of your own voice production can get in the way, as if you were standing naked on stage, surrounded by mirrors! So you might end up insecure & nervous or else stiff & affected.

Undoubtedly, there are public speaking coaches or even speech therapists out there who could break you down and eventually build you back up. (Some people in Boston or the UK pay to shed their regional accents, which I think is a pity.)

Instead of paying more attention to personal mannerisms, I'd recommend thinking less about yourself. Practice engaging strangers in conversation. Random people behind the counter, at bus stops, taxi drivers, etc. Try to work in a story. If they're not squirming to get away, then you're doing well.

You're not trying to be a disembodied voiceover artist. You're trying to speak to people. Really, what matters is what you're telling them and how you spin the story. Gilbert Gottfried can mesmerize a crowd, and he sounds like a crow mid-strangulation.

How to improve the quality of your voice?

Breathe slowly and deeply.
Correct breathing is one on the first fundamentals for singers, martial artists, and yoga students.

Speak slower.
Slowing your pace of speaking will deepen the tone of your voice and make it easier to listen to. Also your words will tend to be better enunciated.

Stand tall.
Correct posture weather sitting or standing allows you to breathe easier and project well.

Don’t strain your throat.
Be well rested. Avoid speaking at the time of day when you are low on energy. Don’t yell. Use a microphone when appropriate.

Avoid dairy products.
Before speaking don’t drink milk or eat cheese because that tends to create phlegm in your throat. The safest liquid to drink is lemon tea or room temperature water.

Yawn.
Immediately before speaking, yawn (discreetly). This relaxes your throat. Morgan Freeman confessed that he uses this technique regularly.

Want more tips and help? Contact me for more...
George Torok

PS: I hosted a radio show for 19 years and have been coaching and training presenters for at least 19 years.

You don't say what it is about your voice that you'd like to improve. So the first thing to think about is -- what don't you like?
If you want better projection ground yourself before you speak. Make sure you are standing solidly on both feet and draw your breath up from the ground and out your mouth. Think of your body as a bellows.The greater/deeper the breath, the more powerful the sound.
If you are concerned with sounding monotone, take a song you know well, and speak-sing it. It's not about hitting the notes, but putting "musicality" into your voice by using a varying your pitch and speed.
Speak more slowly than you would conversationally, to give people time what you're saying. Pause.
Finally, if you have an unusual voice, consider the possibility that it could be a great differentiator. Arnold Schwarzenegger's accent...Victoria Jackson's high pitch...Danny DeVito's Brooklynese all give them a kind of memorability they wouldn't have if they sounded like everyone else.
I teach Public Speaking skills. I'd be happy to discuss this with you further.
Good luck!

Voice will raise and go down depend on the topic which you discuss in turn shows the confident about the topic.

The voice always get the attention of opponent that depends on what pitch you are in. A graph plot should show the proper voice as a sinusoidal wave with ups and down that is the perfect way of communicating. It cannot be with higher pitch or lower pitch always.

Increase your voice based on the points which you like to stress and come back to normal which it is not required that's how the points will be registered with opponent.

Lot of things are connected with voice example SHOUTING 1. to get the attention of someone
2. to show angry
3. to show confidence
4. to show commanding etc......

we can discuss more like this

The more you try to perform, the greater your chance to black out will become and your voice quality will deteriorate. Should you ever feel a blackout coming on, the more you breathe, relax, stay curious and serve, the less chance you will actually black out and sound of your voice will improve.
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath

This is less about developing your voice and more about developing your confidence. When we change the story inside, what we project to the world changes. I would argue that your voice is probably fine and all you need is a shift in mindset.

Hope this helps!

Best,
Jon Ebner
Competitive Public Speaker and Trainer