ECHO, is also used for the place where the repetition of the sound is produced or heard.
Echos are distinguished into divers kinds, viz.
1. Single, which return the voice but once. Whereof some are tonical, which only return a voice when modulated into some particular musical tone: Others, polysyllabical, which return many syllables, words, and sentences. Of this last kind is that fine echo in Woodstock-park, which Dr Plot assures us, in the day-time, will return very distinctly seventeen syllables, and in the night twenty.
2. Multiple, or tautological; which return syllables and words the same oftentimes repeated.
In echos, the place where the speaker stands is called the centrum phonicum; and the object or place that returns the voice, the centrum phonocampicum.
At the sepulchre of Metella, wife of Crassus, was an echo, which repeated what a man said five times. Authors mention a tower at Cyzicus, where the echo repeated seven times. One of the finest echos we read of is that mentioned by Barthius, in his notes on Statius's Thebais, lib. vi. 30. which repeated the words a man uttered 17 times: it was on the banks of the Nalla, between Cohientz and Bingen. Barthius assures us, he had proved what he writes; and had told 17 repetitions. And whereas, in common echos, the repetition is not heard till some time after hearing the word spoke, or the notes sung; in this, the person who speaks or sings is scarce heard at all; but the repetition most clearly, and always in surprising varieties; the echo seeming sometimes to approach nearer, and sometimes to be further off. Sometimes the voice is heard very distinctly, and sometimes scarce at all. One hears only one voice, and another several: one hears the echo on the right, and the other on the left, &c. At Milan in Italy, is an echo which reiterates the report of a pistol 56 times; and if the report is very loud, upwards of 60 repetitions may be counted. The first 20 echos are pretty distinct; but as the noise seems to fly away, and answer at a greater distance, the repetitions are so doubled, that they can scarce be counted. See an account of a remarkable echo under the article PAISLEY.