The ultrasonic wave propagation characteristics were measured for IN‐100, a powder metallurgy alloy used for aircraft engine components. Attenuation, velocity, and backscattered microstructural noise were measured on several research samples. The data were obtained with a variety of different transducers placed either in a waterbath or in sample contact for a frequency range from about 2 to 18 MHz and statistically averaged over numerous volume elements of the samples. Micrographical examination provided size and number distributions for grain and pore structure. The results showed that the predominant source for the ultrasonic attenuation and backscatter was a dense (∼ 100/mm3) distribution of small micropores (∼ 10 μm radius). Two samples with different micropore densities were studied in detail to test the feasibility of calculating microstructural parameters from ultrasonic backscatter data in the regime for which the wavelength is much larger than the size of the individual scattering centers. The results suggest a way towards the nondestructive detection and characterization of anomalous distributions of micropores in a variety of materials when conventional ultrasonic imaging is difficult. The findings are potentially significant toward the application of the early detection of potential sites for stress‐induced void coalescence leading to crack initiation and subsequent failure.