The Easy and the Hard Part of Controlling the Acoustics Of Rooms

From time to time, audiologists are asked about strategies (and products) that can be used to reduce the echoes in rooms in hopes of improving speech intelligibility or to “flatten” the room’s acoustics for music listening and playing. Other than seeking out the assistance of an acoustic or audio engineer (which actually can be well-worth the expenditure), this is a primer on how sound behaves in a room, and how it can be modified. An audiologist may be approached by an “audiophile” who has done a spectral sweep of a room and noticed an unwanted resonance at 120 Hz or 130 Hz, for example. How can we best respond to this inquiry?