| 释义 |
phon|fɒn|
[a. G. phon (H. Barkhausen 1926, in Zeitschr. für techn. Physik VII. 601/1), f. Gr. ϕωνή sound.]
A unit of loudness (strictly, loudness level), defined so that the loudness in phons of any sound is numerically equal to the intensity in decibels of a pure 1000 Hz tone judged to be equally loud. Formerly = decibel.
1932B.B.C. Techn. Tables & Gloss. 63/2 Two noises may be compared in strength in sensation units or phons by comparing the attenuations necessary to reduce each to the threshold of audibility. 1932Engineering 9 Sept. 314/3 For quantitative measurements we turn to a unit called the decibel. [Note] Called the ‘phon’ in Germany. 1935Sunday Times 13 Oct. 18/3 Now a machine exists which measures units of noise in ‘phons’, and no vehicle will be allowed after a certain date to make more than 90 phons of noise at a speed of 30 m.p.h. 1937A. H. David Noise iv. 46 Originally a ‘phon’ had been used in Germany as a four-fold power ratio. Later it was employed as an equivalent of the decibel. Ibid., Limitation of the decibel to intensity ratios and the phon to loudness scales has been adopted by the British Standards Institution. 1942Wireless World June 132/2 The magnitude of these upper intensity levels in terms of loudness can be expressed by writing phons for decibels, since they are equal, in the range here considered. 1959G. R. Partridge Princ. Electronic Instruments xvi. 303 A loudness of 70 phons requires 80 db intensity at 70 cycles. 1962A. Nisbett Technique Sound Studio 264 Phons equal decibels at 1000 c/s, and at other frequencies are related to this scale by contours of equal loudness. 1963Jerrard & McNeill Dict. Sci. Units 104 The loudness of a jet aircraft engine is about 140 phon, whereas the noise of a steam railway locomotive is less than 100 phon. 1974Daily Colonist (Victoria, B.C.) 22 Nov. 16/5 Tokyo metropolitan government standards set permissible noise levels at 40 phon (sound measurement) in the morning and evening and at 45 phon during the day. |