This is an evaluation of the performance of a new nondestructive method for measuring the compressive strength of isolated concrete masonry units (CMUs) and related units using acoustics. The method, called the acoustic impulse response resonance (AIRR) method, involves gently striking the unit being tested with a pendulum and analyzing the resulting sound. It requires little extra time and effort to use the AIRR method in conjunction with standard strength-testing projects, where it is useful for corroborating compression test results and identifying sources of variation in the measurements. Precise measurement of strength maturation can be quickly achieved through repeated testing of individual units. The AIRR method can be quickly performed virtually anywhere, which makes it possible to engage in a variety of useful testing scenarios. The AIRR method is also suitable for use in regions where standards are lax or where trusted compression-testing facilities are not accessible, not feasible, or not used. The present paper extends the AIRR method to accommodate variations in the shape of the unit being tested. Finite element analysis was used to gain insight into the vibrational modes of CMUs and to establish a basis for accommodating shape variants, referred to here as shape normalization. Evaluations were performed using data collected at the National Concrete Masonry Association (NCMA) Research and Development Laboratory, where the AIRR method was applied along with standard testing for 81 ASTM C140/C140M projects. The tested units were hollow CMUs with a range of standard widths. The AIRR method was shown to be extraordinarily repeatable within the constraints of the variables evaluated, and shape normalization was shown to be effective. A strong correlation with estimates of compressive strength obtained through compression testing was demonstrated, and there is evidence that the AIRR method has the potential to be more precise than compression testing.