Auditory phenomena may be divided into two categories: provoked automatisms, and spontaneous automatisms or _clairaudience_. The first may be considered as hallucinations induced by diverse methods. The simplest method consists in the use of certain shells, horns, trumpets, or, in a word, any object capable of augmenting and allowing the perception of those external or internal sounds, which are not usually perceptible to the hearing. This is what is observed particularly with some sea-shells. When we apply them to the ear, we hear a murmur or a slight rumbling sound. This sensation is common to every one, and children are accustomed to play at ‘listening to the sound of the sea in the sea-shells.’ Some people do not hear this sound, or rather, when they listen, it quickly disappears and makes way for words and phrases. I know a subject with whom this faculty exists, but circumstances, unfortunately, have prevented me from studying him carefully. I point out, to the attention of observers, the interest which this automatism presents; the rapidity of communication is very great; in this way there is a greater output than with automatic writing, and it is less tiring for the sensitive. The only precaution to observe is to take down all he says in shorthand. We must accustom him to repeat, instantly, everything he hears, because words heard in this way are speedily forgotten—as in dream—but amnesia is not the sole point of resemblance between this automatism and dream. It has much analogy with visual automatism, but it has an interesting advantage over the latter. Visual images are those which offer the highest degree of symbolism; they are vague, wanting in precision, and require interpretation. Auditory hallucinations, on the contrary, have greater precision. Perhaps this is due to language, the usual manner in which auditory images are revealed. On the other hand, they are not so rich, and contain less detail than visual images do. The meaning of auditory messages is seldom very clear; but there are cases where it is wonderfully so. Such are the chief features of provoked auditory phenomena. I have given too little attention to this phase of manifestation, to be able to enter into a more complete analysis of it. _Clairaudience_ is more frequent; perhaps this is due to the negligence of experimenters, who do not think of using the methods of induction I have just described. I have rarely observed the existence of isolated auditory hallucinations; I have always observed them associated with visual hallucinations; therefore I will study them after these last, when examining mixed phenomena.