ADDED SOUNDS IN THEIR RELATION TO ALTERED BREATH AND VOICE - next to consider what further light is afforded by superadded sound, as to the causes of that change of structure which has been indicated by alterations in breath and voice-sound and in percussion resonance; and also what they teach us con cerning the state of the lungs, in cases in which we have been unable to detect any change of density.
Various modes of classification have been adopted by different authors, but they have all been framed more or less on theories regarding the mode of development, either with reference to the situation in which the sound is supposed to be generated, or to the amount of fluid assumed to be necessary for its production. The names which authors have thus either fancifully or theoreti cally imposed upon these sounds have too often only served to mislead the student, by causing him to attach the idea of apar ticular condition of disease to the name of some given sound, or by rendering it impossible to understand the exact character of one upon which various names have been bestowed. We have endeavored in the preceding chapter to limit the names used to terms expressing the character of the sound heard, and the same course will be followed with reference to this new class of phe nomena, in so far as it can be done without roughly discarding customary terms. Perhaps there is no advantage in classification at all, but it may tend to simplify matters if the superadded sounds be divided into interrupted and continuous—including in the former those that consist of a series of distinct noises or minute explosions, and in the latter those that form only one prolonged sound.
§ 1. Interrupted Sounds.
a. Crepitation consists of a succession of fine crackling sounds, commonly so minute and so close together, that the ear can scarcely detect their distinctness.
b. _Moist Sounds ; the least objectionable term which has been employed to designate a rattling noise, in which the separation of the individual explosions is more distinct than in crepitation they convey the idea of air passing through a small quantity of' fluid in minute bubbles.
c. Gurgling Sounds are only a modification of moist sounds, but are yet easily recognized as a class by themselves, the air evi dently gurgling or passing in large bells through a considerable amount of fluid.
d. Metallic Tinkling.—This might also be called amphorio dropping, conveying to the ear the idea of distinct drops falling with a plash in a large space, and producing a ringing metallic noise.
e. Closely connected with the preceding is the plashing sound heard when the patient moves quickly, or is shaken, in cases of hydro-pneumothorax. It is called the sound of succu.ssion.
These sounds pass by insensible degrees into each other. Cre pitation may be so very fine as to be mistaken for a continuous sound (of friction for example), or it may be so very coarse. as to be analogous to a moist sound ; theoretically very distinct, the value of such sounds can only be estimated practically by the coexistence of other phenomena. Moist sounds may be divided into fine and coarse ; they hold a position intermediate between crepitation and gurgling. Among these may be classed a sound which has been very inappropriately called diy crackling, which oonsists of single clicks, recurring at longer or shorter intervals ; when speaking of it apart from moist sounds, of which it is, in certain circumstances, the precursor, it will be distinguished by this character. Another modification is the squeaking sound, which approaches to gurgling, and conveys the idea of a large bubble, formed rather in consequence of the viscidity than of the quantity of fluid. Gurgling,.again, sometimes consists of solitary bubbles, at very considerable intervals, explocling in a large empty cavity with a hollow metallic or amphonc ring, which is scarcely distinguishable from metallic tinkling.
2. Continuous Sounds.