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Effect of Conical Horns on the Intensity of Sound Emitted by an Organ Pipe
Phys. Rev. 22, 73 – Published 1 July, 1923
DOI: https://doi.org/10.1103/PhysRev.22.73
Abstract
Effect of conical horn on the intensity of sound emitted by an open organ pipe.—In a room lined with hair felt one inch thick to reduce resonance effects, readings taken with a Webster phonometer showed that while the horn (50 cm long, 6° flare) doubled the intensity, it acted merely as a resonator and did not concentrate the energy in front to any measurable extent. Outdoor experiments gave the same result except that the intensity was increased by only one half.
Webster phonometer with a disk supported by wires under tension, is a convenient portable instrument, as sensitive as the ear to the pitch to which it is tuned, but it shows a very sharp resonance to the natural frequency of the disk and this selectivity limits its usefulness.
Rayleigh disk phonometer is described. It may be used to measure the absolute energy density of sound.
References (2)
- Webster, Boltzmen Memorial Volume 1904 King, Phil. Trans. 218 (1919)
- Sabine, Collected Papers on Acoustics, pp. 166 and 233