Driver design—including the particular way two or more drivers are combined in an enclosure to make a speaker system—is both an art, involving subjective perceptions of timbre and sound quality and a science, involving measurements and experiments. Adjusting a design to improve performance is done using a combination of magnetic, acoustic, mechanical, electrical, and material science theory, and tracked with high precision measurements and the observations of experienced listeners. A few of the issues speaker and driver designers must confront are distortion, radiation lobing, phase effects, off-axis response, and crossover artifacts. Designers can use an anechoic chamber to ensure the speaker can be measured independently of room effects, or any of several electronic techniques that, to some extent, substitute for such chambers. Some developers eschew anechoic chambers in favor of specific standardized room setups intended to simulate real-life listening conditions.