If the signal from an acoustic source consists of arbitrary pulses which are separated in time by an interval large compared to the length of the individual pulses, a series of simple mathematical operations performed on the pressure and particle velocity as measured at a point will yield an expression from which one can determine the distance between the source and the field point. The term containing the distance is measurable only in the near field and becomes less than 10% of other terms at distances greater than the wavelength corresponding to the dominant frequency of the pulse. The theory is presented for spherical and dipole sources. Experimental measurements made in air are presented for various pulse shapes from a dipole source and are compared with the theory. The effect of a noise background on the method is also considered.