Genderlessvoice.com offers a voice that they say is not gendered. Under the assumption that gender is a social construct (which is usually the case if you think 'gendered') it seems weird to call a voice gendered or gender-less for that matter. A voice is attached to a person who constructs the gender of the whole body. A voice alone cannot be gendered in the first place. In the intro they claim that 'male' voices are in such and such frequency spectrum and female voices in such and such spectrum of Hertz, which goes very close to some good old-fashioned essentialism, which seems odd. If they'd really defend that viewpoint, why not call it sex-less voice? I, for what it's worth, think that what we associate with which sex is still largely societally construed but more in the way of which biological functions are attributed to what sex, rather than which behaviours are attributed to what gender. It just seems that gender is such a high-level construct, devoid of any wet-ware, that it seems off to call a voice gender-less. Furthermore it kind of excludes trans folx, especially MTF, since the vocal cords are one of the things that don't change on HRT. As some trans people say themselves: "A voice is found, not made." I quite like that, especially since it plays into the idea of gender being constructed/(found).

The makers of genderlessvoice.com might just mean, that it isn't interpreted in a particularly sexed/gendered (since it's not clear to me what they advocate for) fashion. But that seems awfully pragmatic because it puts the interpretation of the gender into the hands of other people rather than yourself and your behaviour/gender ought to be largely determined by yourself.