Board Thread:Poll Archive/@comment-35301431-20130720165941/@comment-53539-20180524212815

Len'svoice is awkward because its neither like Oliver's or like the other post puberty boys and how they sound. In reality its a deep voiced female and has some traits missing from that of a male vocalist. Most think that pitch is the only trait of a male vocal, but there are other issues such as moisture that impact a male voice due to the voicebox growing and all that.

This is an issue also addressed by the Japanese fandom, who also feel that at times Len has issues with masculinity. So its not just western fans who have an issue with this. At times Len can sound not masculine at all, depending on the voicebank you use.

All of this is because they used an adult female vocalist, and while you can get away with it for animation, in reality to music its not 100% a perfect match. The reason they use women for voice acting is the forementioned issue of puberty, and characters like Max and Kenny from Beyblade, or Phineas from Phineas and Ferb, and even Harry Potter's actor, all demonstrate the issue as their voices broke during the runoff the things they were based on. Adult females can do the same vocal range as males as children, however... Adult vocals are naturally much harder then child vocals. You never get a perfect fit for this reason, you either use a child and hope for puberty not come along, or use an adults and remain stable but not a perfect match.

It doesn't always matter, CFM are known to alter samples to make their vocaloids have a certain quality to them, Kaito and Meiko not being subject to the same treatment. Len can often barely sound like his provider these days, because they over do it at times. Even if they weren't doing that, naturally he is still considered the least realistic member of the CV series for a reason.