Purpose: The aim of this experiment was to compare, for patients with cochlear implants (CIs), the improvement for speech understanding in noise provided by a monaural adaptive beamformer and for two interventions that produced bilateral input (i.e., bilateral CIs and hearing preservation [HP] surgery). Method: Speech understanding scores for sentences were obtained for 10 listeners fit with a single CI. The listeners were tested with and without beamformer activated in a "cocktail party" environment with spatially separated target and maskers. Data for 10 listeners with bilateral CIs and 8 listeners with HP CIs were taken from Loiselle, Dorman, Yost, Cook, and Gifford (2016), who used the same test protocol. Results: The use of the beamformer resulted in a 31 percentage point improvement in performance; in bilateral CIs, an 18 percentage point improvement; and in HP CIs, a 20 percentage point improvement. Conclusion: A monaural adaptive beamformer can produce an improvement in speech understanding in a complex noise environment that is equal to, or greater than, the improvement produced by bilateral CIs and HP surgery.