Do animals have different vocal ranges?

Joanne called the show and had this question for animal communication expert Jacob Dunn from Anglia Ruskin University.

Jacob - Hi Joanne. That’s a really good question. There is obviously a difference in the frequency in the voice in humans as you rightly say, so male voices tend to be about 75 percent lower frequency than female voices. Interestingly, this is something that, as we all know, doesn’t happen all the way throughout our lives.

In other animals - I know most about primates -  but it’s true in some other animals as well. Whether there is a difference or not between males and females seems to be related to the mating system. So in those mating systems where males compete more ferociously for access to females and have harem groups and so on, there tends to be a more exaggerated difference between the males and the females. And in other species that are perhaps monogamous, and there’s not such high levels of competition between the males, then the difference between the males and females tends to be less.

So in answer to Joanne’s question yes, we do see this in other species and it seems to be linked to the competition between the males, and the mating system.

Chris - Happy with that Joanne?

Joanne - Yes. But in those cases, is there evidence of it changing during the animal’s lifetime like it does in the humans then?

Jacob - Yeah. Again that’s a really good question. And yes is the answer through the same mechanism. The reason that the voice frequency drops in male humans is because it’s linked to testosterone. The vocal folds, as they lengthen, anything bigger vibrates at a lower frequency so as you get longer vocal folds, your vocal frequency gets lower and, therefore, you have a lower pitched voice. And that growth in the vocal folds in boys and in the male voice is linked to testosterone. And through that same mechanism in other animals as they get higher testosterone their vocal folds lengthen.

Chris - I did notice in my dog - I had a puppy. And he had a yap that as he turned into a big strapping great labrador became much more of a bark, so that the size thing isn’t it? Jess?

Jess - Can I ask you a question about bonobos? I was recently in San Diego and met this phenomenal scientist called Amy Parish who researchers bonobos and they’re a matriarchal society rather than a patriarchal society like chimps. So there do the women have deeper voices because they’re in charge or do they have higher pitched voices?

Jacob - That’s a really good question. It’s more complicated than there only being mating systems in which a male has a harem or monogamy, there are lots of other different kinds of organisations. Sometimes you just have one female that has multiple males - it’s called polyandry. And very often among primates and lots of other animals you have this polygynandry, multiple males and multiple females in a sort of promiscuous arrangement, and so the communication system will reflect that.

Some species like bonobos and spider monkeys as well, the females are pretty hardcore and they will beat up the males and that will be linked to the higher testosterone and lower vocal frequency, yes.

Chris - So the bottom line is, Jess is right, they’re going to have a deeper voice. There you go Joanne. I hope that answers your question. Thanks for calling in.