This is not a Lego chair, rather it is a chair whose contour resembles the chart (shown) showing sound waves mapped on a 3D graph of volume (height), frequency (depth), and time (width).
The London-based designer, Matthew Plummer Fernandez had to experiment not with his drafting board but with more than 700 sounds in order to get this chair design. The actual chair is made up of water-jet-cut polyethylene foam so it is comfortable enough to sit on. But the price might be a tad too loud - $7,280!
Matthew Plummer Fernandez
Pearl — September 28, 2008 — Art & Design
References: plummerfernandez & dvice