Trust the Process

Everyone who hears the disembodied voice singing immediately and unerringly identify it as a boy singing, even before anyone has any idea as to the identity of the singer. However, the singing is pretty and high-pitched, sounding extremely feminine. Even if they don't accidentally identify the singing as a little girl, there should at least be some uncertainty as to the gender of the singer, they shouldn't be so certain based on nothing except hearing the voice.

References What Ever Happened to Baby Jane? (1962)