It’s relatively easy to achieve flat frequency response in an anechoic chamber. But, in the real world, the sound of loudspeakers is highly dependent on the room they’re in. Room-induced bass non-linearities are problems that have generated lots of solutions. One of the most common is active equalization, often processed in the digital domain. The downside is that insertion of an electronic equalizer into the audio signal produces deleterious audible effects in the rest of the frequency spectrum.