What is neutral speech? At the horizon of this research there was the uncertainty that an ideal speech exists. This writing reports the results obtained of research in phonostylistics of Brazilian Portuguese with the objective of determining the necessary experimental conditions for recording so-called neutral speech. The experiment was designed to test these two hypotheses: 1) The phrase, or sentence, the minimal prosodic unit, is also the minimal unit of meaning in studies of expressing emotion in speech, even when our focus is on the production of complete texts that should be taken as a single unit of meaning. 2) The speaker's reported selfimpressions can indicate certain sentences that have been affected by the reactions of the speaker, which conflict with the objective of recording neutral speech, and therefore should be rejected from a corpus of referential speech. The results obtained validated both of the hypotheses and enabled us to formulate a single unique test for neutral speech, recommended for the process of purging of referential corpora in experimental phonology, which is described in this work.