150. Spirits produce not only noises and rappings, but cries of every kind, and vocal sounds imitating the human voice, in rooms, and in the open air; phenomena which we designate as pneumatophony, or spirit-sounds. Our experience of the nature of spirits has led us to think that some of them, of an inferior order, delude themselves into the belief that they are talking, as when in the flesh. (See the Revue Spirite, February 1858 ; History of Mademoiselle Clairon's Ghost.)
We must be careful not to take all sounds, the cause of which we know not, or mere tingling of the ears, for occult voices, any more than to share the silly fancy that, when our ears tingle, some one is talking about us. Those tinglings, which have a purely physiological cause, are without meaning; while pneumatophonic sounds express thoughts, and thereby prove themselves to be due to an intelligent cause, and not to accident. We may lay it down as a rule that spirit-intervention is only proved by intelligent manifestations, in all other cases, there are a hundred chances to one that what are taken for such are really due to fortuitous causes.
151. It often happens that, when we are asleep, we hear words, names, sometimes entire phrases, pronounced with sufficient force and distinctness to waken '15 with a start. Although, in some cases, this may be a spirit-manifestation, it is often attributable to the cause of which we treated in our remarks on hallucination (Chap. VI. III, et seq.) What is thus heard has usually no coherence, thus differing widely from spirit-utterances, heard when we are awake ; for in such cases, we Can usually exchange thoughts with the speaker and enter into regular conversation with him.
There are two very distinct ways in which spirit-sounds are perceived; they are sometimes heard by a sort of interior hearing, in which case, although the words heard are clear and distinct, they are not of a physical nature; at other times, these voices are perceived as something exterior to ourselves, and appear to be as distinctly articulated as though spoken by a person at our side.
However produced, the phenomenon of pneumatophony is almost always spontaneous, and can rarely be obtained by evocation.