Tone and Timbre.
Language Log had an interesting post on American/Japanese voices. Based on their [non-controlled] data, they found that Japanese speakers had a 1-3 semitone increase in gender polarity from American speakers. That means that Japanese male speakers would sound slightly lower than American males, and Japanese females would sound slightly higher than American females. (This is probably well-observed in dubbing for female characters in movies and shows.)
After reading that, I ran through several random phrases to see if it was true for me when I speak English and Japanese, and apparently it is! (When I matched my Japanese voice to my English voice, it sounded weird.)
This is particularly interesting to me because it means that despite the fact that these languages are intonal, there is still an implicit amount of tonal information that isn't consciously registered by the speaker and listener. Mandarin, by contrast, is a tonal language, and relies heavily on pitch-relative-to-voice.
In a sense, even if we're only monolingual, we can still tell the general voice range of a person's speaking voice based on the timbre. In music, this is obvious when a singer is scraping the top or bottom of her range to hit the notes. Although the notes themselves are physically possible for humans, they aren't reachable for all, and the "strain" in the voice can be heard. (Sometimes seen as well, from the clenching in the neck area.)
This actually puts into perspective, my interactions with two asians from highschool. The first was a Korean female who, to my English ears, spoke in an affected higher voice. I thought she was just trying to sound cute (and failing) -- since I had heard her "normal" voice when she was upset. But maybe the higher tone was a symptom of her Korean upbringing. The second, very similar, was a Japanese male who normally "mumbled". But whenever he would raise his voice (both in pitch and volume), he would sound "normal".
The curious thing about both these cases, is that they were both born and raised in Toronto, a predominantly English-speaking community. Sorta makes one wonder how much of foreign accents are actually contributed by misaligned speaking ranges.