Virtual Voices: Replicating the Sounds Produced By Big Cat Throats
It sounds highly unusual when you first consider it. After all, whilst there are people who would be quite happy to embody in the total sensory immersion of a lion or tiger avatar form, and interact with the virtual environment as a powerful feline, why would there be any desire for them to sound like one?
Well, it is worth remembering that embodiment does not solely address an outside user embodying through an avatar, but also a-life creations and similar beings to whom the avatar is their only body. If you have a pet tiger in a virtual environment say or you are studying a simulation of their natural behaviour then every physical aspect should be as close as possible to how it would be physically. With the research example, exact simulation is a must of course, but even with a beloved virtual pet, you are still looking for believability, and authentic sounds, preferably without having to rely on pre recordings to do so.
Of course, for those who actually do wish to embody as a given animal form, actually possessing the vocal range of the being they are embodied as, has it's own appeals. Trying to talk in English with a tiger's mouth could be fun for example. But, in order for any of this to be possible, you have to first understand what drives a big cat to sound as it does.
As with everything else in avatar design and embodiment, if you wish to duplicate something virtually, it is essential to understand how the original works.
This is where it gets interesting. A recent study in PloS one, has found that the roar of a big cat is not as you would think, governed primarilly by nerve impulses from their brain. The impulses are there of course, but it is the unique larynx structure, not the electrical impulses, that shape the roar into what it becomes. In fact, the same basic neural codes a human baby uses to make sounds, produce the entire range of lion and tiger sounds when the larynx structure modulates them.
If the same is true for other big cats, which seems very likely, then it may also be true for other mammals. If so, then we have discovered a kind of vocal filter that can be applied to naturally made human grunts, squeals, or even speech to have it sound like it came from a real mammal, of whichever type was desired. The properties of the embodiment themselves altering the vocal result without any additional effort from the user.
In the physical animals, it was found that the ability of the vocal fold tissue to stretch and shear was what controlled the timber and pitch of the output. The vocal folds are very loose and gel-like and create a rough, irregular output that grates slightly on the ears.
The new study's key finding is that lions and tigers can roar loudly and deeply because their vocal folds have a flat, square shape and can withstand strong stretching and shearing. That contradicts a theory that lions roar deeply because the vocal folds are heavy with fat.
Instead, the fat helps give the vocal folds their square shape where they protrude into the airway, unlike triangular vocal folds in most species. The fat also may cushion the vocal folds and provide repair material when they are damaged, according to the research.
Measurements of vocal fold resistance to stretching and shearing let researchers accurately predict the "fundamental frequency" ranges at which lions and tigers are known to roar, and the lung pressures needed to produce those roars. Both types of data can be fairly easily added as variables into an embodied avatar, giving a new dimension of control to virtual voices.
Whether the basic voice is a human's or an artificial voice stream of one type or another, this work strongly suggests a normal voice, or at least the neural impulses that would normally power a voice, can be adapted after being read, to produce perfectly natural sounding calls across the spectrum, for whatever species they end up embodied as.
That will certainly please those who dream of being anthropomorphic animals, as well.