The triangle is a small instrument made of a metal rod bent into a triangle shape that is open at one corner. While small, its sound is distinct, with multiple overtones and nonharmonic resonance.

Triangle-shaped notebook that opens into a square. Read More. $33 at Tan Mavitan Studio $33 at Amazon. Sidekick Notebook $24 $24. Notebook shaped like an “L” to wrap around your keyboard.

The article “How the musical triangle’s shape influences its sound” is authored by Risako Tanigawa, Kenji Ishikawa, Noboru Harada, and Yasuhiro Oikawa. It will appear in JASA Express Letters ...