An experimental technique is presented for the determination of normal acoustic properties in a tube, including the effect of mean flow. An acoustic source is driven by Gaussian white noise to produce a randomly fluctuating sound field in a tube terminated by the system under investigation. Two stationary, wall‐mounted microphonesmeasure the sound pressure at arbitrary but known positions in the tube. Theory is developed, including the effect of mean flow, showing that the incident‐ and reflected‐wave spectra, and the phase angle between the incident and reflected waves, can be determined from measurement of the auto‐ and cross‐spectra of the two microphone signals. Expressions for the normal specific acoustic impedance and the reflection coefficient of the tube termination are developed for a random sound field in the tube. Three no‐flow test cases are evaluated using the two‐microphone random‐excitation technique: a closed tube of specified length, an open, unbaffled tube of specified length, and a prototype automotive muffler. Comparison is made between results using the present method and approximate theory and results from the traditional standing‐wave method. In all cases agreement between the two‐microphone random‐excitation method and comparison data is excellent. The two‐microphone random‐excitation technique can be used to evaluate acoustic properties very rapidly since no traversing is necessary and since random excitation is used (in each of three test cases only 7 sec of continuous data was needed). In addition, the bandwidth may be made arbitrarily small, within limits, so that the computed properties will have a high degree of frequency resolution.