This area is going to be extremely sparse since Freelancer.com isn't good for much other than "need female AMERICAN native accent read list of words!" Which I've done a few times now, to clients' full satisfaction. I've been told by many people I'm good with voices, and as a singer/music producer, I already have the skills to master (and mix, if you're looking for that!) vocals to their best quality, without background noise, and always deliver them in high quality WAV format. If you want any effects, or even music (my forte!), and any sound effects (note, my microphone is portable, so I can capture anything from anywhere, even though I record my vocals in a quiet sound dampened area), it can be done. If you want a chipmunk voice, or something comically low pitch, it can be done. Your imagination is the limit - although I must confess I'm not very good at providing "male" vocals, since my voice is so high. Melodyne can only be stretched so far before the quality drops. :P
I'm a Texas Music Educator's Association (TMEA) certified music scholar, class of 2009. That means I've had to win some solo singing awards, attend musical classes, and go on a few musical oriented trips. I'm also a self-taught Ableton music producer, part-time (very... part-time...) Youtuber, and
I have a portable high quality battery powered microphone that I can access at a moment's notice, and I use proper Ableton mastering compression and EQ to bring out the best frequencies and eliminate background noise. Ableton, being an industry DAW, also comes with a plethora of audio effects that can be tweaked to user preference, including reverb, delay (think echoey announcements!), and, well, if you're not familiar with a DAW, you'll be pleased to know the other effects are virtually limitless. Melodyne is where the raw audio editing happens, if it's needed or wanted. Pitching and formant changing can be gentle or taken to an extreme (chipmunk voice!), although the more extreme levels often reduce some of the quality. (Psst - if anybody knows anything better than Melodyne, let me know! I love it, but it doesn't really deliver good enough pitching quality for gender changing!)
I think it's pretty much all been said. I'm a music producer and singer, I've done a Youtube collaboration with Ferdk16, sound design and musical collaborative work for an incomplete Twelve Tiles game, and I'm currently earning my bucks as a Freelancer.com voice talent. My dirty secret is I've done "voice acting" my whole life, but I never sought out a market for it until now. Let's do this. B-)