## frequency

**Jim Woodhouse**looks at harmonic and not so harmonic frequencies and at how percussion instruments are tuned.

**David Spiegelhalter** investigates how probability can be defined.

**Chris Budd and Cathryn Mitchell**look at the maths that isn't only responsible for these medical techniques, but also for much of the digital revolution.

**Jeffrey Rosenthal**follows Galileo's observation that the entire universe is written in the language of mathematics - and that includes music.

*Plus*about how he uses mathematics to understand music, and how he managed to combine his passions for music and computing to create a successful career.

Astronomers have for the first time listened to the heartbeat of a star other than our own Sun.

**Robert Leese**explains how the mathematics of colouring graphs can help avoid interference on your mobile phone.