. The Bell System technical journal . d on the axis only 2 from the horn ^ This type of receiver was described by Wente and Thuras in The Bell SystemTechnical Journal, for January, 1928. STEADY STATE LOUD SPEAKER MEASUREMENTS 151 mouth. This curve differs considerably from the one obtained at adistance of 12. The marked depression in the curve at 750 cycleschecks very closely the first interference frequency as calculated for apiston radiator approximately 30 in diameter and allowing for aslight contraction of the radiating surface as the frequency is increased(which assumption would be quite
. The Bell System technical journal . d on the axis only 2 from the horn ^ This type of receiver was described by Wente and Thuras in The Bell SystemTechnical Journal, for January, 1928. STEADY STATE LOUD SPEAKER MEASUREMENTS 151 mouth. This curve differs considerably from the one obtained at adistance of 12. The marked depression in the curve at 750 cycleschecks very closely the first interference frequency as calculated for apiston radiator approximately 30 in diameter and allowing for aslight contraction of the radiating surface as the frequency is increased(which assumption would be quite reasonable for the horn), theirregularities at the higher frequencies are also explained in the samemanner. For the piston, however, the minimum pressure point wouldbe zero, which fact indicates that the wave-front at the horn moutheither is not plane or is not of uniform intensity over the radiatingsurface. Below 1,000 cycles the average trend of this curve is verynearly parallel to the axis of abscissae while as noted for the curve. Fig. 8—Polar curves showing response (expressed relative to axis response) of3J^ piston diaphragm loud speaker at various angles from perpendicular to centerof diaphragm and 12 feet away. obtained at a distance of 12, there is a very definite downward is as would be expected if there were an increasing concentration ofthe sound field about the axis as the frequency increased. The factthat there is such a varying concentration is shown by the data onFig. 4. These curves were obtained with the condenser transmitterat a distance of 12 in each case, but with a line from the center of thehorn mouth to the center of the transmitter making various angleswith the horn axis as specified. In making these measurements, thetransmitter remained fixed and the horn was rotated upward in avertical plane about the center of the mouth. It is apparent fromthese curves that as the angle is increased the response at the higherfrequencies becomes lower, wh
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
