The properties of tonal analogs of speech vary over time. Accordingly, the tones rise and fall in frequency and amplitude in imitation of the frequency and amplitude variations of vocal resonances over the course of an utterance. Note, however, that unlike the natural speech signal, sinewave speech does not have the normal structure -- there are no broadband formants; there is no regularly pulsed source; the normal short-time “cues” found in speech signals are missing; etc. What remains are just 3 (or sometimes 4) rapidly changing pure tones.