They are complementary, not substitutable. Flexible arrangements address when and where employees work. Acoustic workspace investment addresses the quality of the work environment when employees are in the office. For hybrid employees, the office needs to provide something their home environment may not — which is often acoustic privacy and professional work infrastructure. A noisy open-plan office that provides no acoustic workspace gives hybrid employees less reason to come in, while a well-designed office with acoustically appropriate spaces for focused work provides a genuine productivity reason for in-office days.