Which component can be changed to modify a microphone’s pickup pattern?

The capsule is the part of a microphone that significantly influences its pickup pattern. The pickup pattern, or polar pattern, determines how sensitive the microphone is to sound coming from different angles. Different types of capsules can exhibit various pickup patterns such as cardioid, omnidirectional, or bidirectional.

For instance, a cardioid capsule is designed to pick up sound primarily from the front and reject sound from the sides and rear, making it ideal for live performances to minimize feedback. In contrast, an omnidirectional capsule picks up sound evenly from all directions. By changing the capsule, you can effectively modify which sounds are captured by the microphone, allowing for greater control in different recording situations or environments.

Other components mentioned, such as the mixer, cable, or battery, do not inherently change the microphone's ability to capture sound from specific directions. They serve different functions, such as signal processing, connectivity, and powering the microphone, but they do not alter the fundamental way the microphone interacts with sound. Therefore, altering the capsule directly impacts the microphone's pickup pattern, making it the correct answer.