The on-axis pressure response of a vertical line source is known to decrease at 3dB per doubling of distance in the near field and at 6dB in the far field. The present paper shows that the conventional mathematics used to achieve this result understates the distance at which the -3dB to -6dB transition occurs. An examination of the pressure field of a line source reveals that the near field extends to a greater distance at positions laterally displaced from the centerline, normal to the source. The paper introduces the "endpoint" convention for the pressure response and compares the on-axis response of straight and hybrid line sources.
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