Sonic Homework Blog

Poor Man’s Acoustic Treatment, part 1: Books

This post is the first of several, which will cover low and no-budget ways that you can improve your acoustics. This post is about using books to that end.  Shelves full of books make good acoustic diffusers, and unlike a lot of acoustic treatments, they tend to improve a room's decor, or at least not wreck it. Not only that, but guests will (correctly) assume you're very erudite based on your huge book collection.

In general, you could say that acoustic treatment is about minimizing the influence of sound that isn't coming straight out of your loudspeakers and going directly into your ears. There are two main functions of acoustic material that help accomplish this. Absorption, and diffusion. Absorptive materials stop the sound from bouncing off surfaces, and make sure that it never makes it back to your ear. Diffusive materials scatter the sound in random directions, making sure that the sound has to take a longer and more multifarious path back to your ear.

Books are good for diffusion. Basically, the idea is that the irregular profile of books on a shelf acts as a pretty effective diffuser for sound waves. Look at the shape of a commercial diffuser panel compared to a bookshelf.

(Imagine the bookshelf is full of books.)

So, books are a good acoustic treatment, but to cover any significant portion of your walls, you're going to need a crapload of books. Let's assume we need about 10-20 average-sized books to cover each square foot of wall.  Where are you going to get the hundreds or even thousands of books needed to get some good diffusion going? (I'm going to assume you're not actually planning on reading most of them, so I won't worry about literary merit here.)

There are a few possibilities. Sites like or often feature individuals trying to get rid of books.Yard or estate sales might be a good place to find them on the cheap. Church rummage sales invariably have cardboard boxes full of old Tom Clancy hardbacks, and thrift stores might cut you a deal on a quantity of water-damaged romance novels.

Second, ask the local library for their discards. They may already have plans for them, but libraries are routinely forced to dispose of significant numbers of books to make space for more popular or useful titles.

Third, it's a little known fact that bookstores also routinely dispose of mass-market books that don't sell. It's often more expensive to ship unsold books back than throw them out. Instead, they remove the covers and send only those back, as proof that the book in question was not sold, and then dispose of the remainder. If you have a friend that works at a bookstore, it might be possible to get your hands on some of these.

Wait, we're not done.  This is Poor Man's Acoustic Treatment! What is the Poor Man supposed to do about shelving?   You might be able to scrounge up a bunch of free books, but what about the shelves? Bookshelves ain't cheap!

Oh wait, yes they are. The cheapest and most effective mass book-storage method I've seen was the old cinder block-and-board setup. Just  stack boards on cinder blocks until you have the space you need. If you go up higher than about 3 or 4 feet, it's recommended that you attach the top shelves to the wall with brackets. This is particularly suited to this project, because you can customize the sizes of your shelves to treat the exact amount of wall area needed. Shelving isn't free, but it can be done cheaply.

Shelves full of books probably aren't the only acoustic treatment your room needs, but if you cover 20-50% of your walls with books, they'll make a positive and noticeable difference, meaning any further treatment with absorptive material will get you that much closer to the ideal listening environment.

(Sonic Homework LLC is not responsible for anything or anyone that gets wrecked, injured or killed if you build an improper shelving system and are crushed under an avalanche of paperback thrillers.)

Photo by Question Everything @ Flickr

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