Son Goku is definitely one of the most famous characters ever to come from Japan -- but he's still full of surprises. If you, like so many others, grew up watching Dragon Ball Z's English dub, you might not be aware that the Saiyan's original Japanese dialogue sounds a touch different. This is because, in Japan, Goku's voice actor is Masako Nozawa -- a very talented human being with a prestigious career, who also happens to be a woman.
Masako voiced Goku from the very first episode of Dragon Ball when he was just a little kid. There's nothing unusual in itself about this as young boys are often voiced by women in Japan, and in many other countries as well. One might think, however, a voice change would have been in order once Goku reached manhood, but this was not the case. Masako has continued to voice Goku in every one of his Japanese appearances, right up to the present day. In fact, she even holds a Guinness World Record for "Longest Time In the Same Video Game Role"-- the role, of course, being Goku. As well as this, she voices Gohan, Goten, and just about every male character related to Goku.
So why has Masako stayed in the role all this time? The main reason might just be convention. Women voicing male characters are much more common in Japan than they are in America. There are many famous examples of this, from Fullmetal Alchemist's Edward Elric to Naruto's titular hero. Of course, these characters tend to be younger men, so to hear an older woman's voice coming from the muscular father of two that is Goku is a bit more unusual.
Another big reason is that she's popular, both with the fans and with several other important figures. Akira Toriyama, the creator of Dragon Ball, stated that when he first heard her audition, it matched exactly with how he imagined Goku's voice in his head. It doesn't hurt to have the creator of the anime on your side as an actress. All in all, it would seem that everyone thought she was doing a good job, and simply saw no need to replace her.
Whatever the reasoning might be, it really all comes down to personal taste. Some argue that this high, childish voice better serves the legendary Saiyan's character. Goku is, for all his power, depicted as an innocent, fun-loving guy, so in some ways, this voice is perfect for him. Other people are not so enamored. There are no tricks done to Masako's voice in the recordings making it still very obvious that she's a woman. Some fans just feel that it undercuts the drama and would prefer to hear someone a bit more manly bellowing "Kamehameha." It all comes down to what you like.
Whatever your personal preference is, however, it's hard to deny that Masako Nozawa has left her stamp on the character. She's in her 80s now -- here's hoping she'll have many more years left voicing the powerful Super Saiyan she loves so much.