Virgil Thomson wrote about Elsie Houston a number of times while he was a columnist for the New York Herald Tribune (he was also a friend). A typical comment:

Miss Elsie is a great artist, a magnificent personality, and a practically unique mistress of vocal art.

And I think his take on her singing (which matches Harry Partch's conception to some extent) is on the mark. From a column following her Town Hall concert:

Few are the vocal artists whose range of color can compare with hers. Her musicianship is impeccable, her repertory distinguished, her voice agreeable, her diction tops. About the only thing she does not do well is to sing normally...Miss Houston does not vocalize classically, she vocalizes verbally...She is at her best when she evokes natural speech by musical sounds. These sounds are true musical sounds and her dramatic expression is true and easily communicated. Her whole performance is as practiced, masterful, and sophisticated as that of Lotte Lehman, for example. It is different, however, because it is built on a wholly different assumption...Carrying power, sheer vocal volume she throws out the window, sacrificing its advantages for the greater range of color and expressive range.