Listen to Pulsars
Pulsars are highly magnetized, rapidly rotating stellar remnants with the magnetic axis tilted with respect to the rotation axis. Synchrotron radiation is emitted from the poles, and as the pulsar rotates, it sweeps this beam of radiation through space. If this beam sweeps by the Earth, a pulse of radiation is seen. An illustration of a pulsar can be seen in the following, showing the radiation beam in purple and the blue surfaces representing equi‐vector magnitudes of the magnetic field strength of an ideal dipole.
Pulsars rotate at many different speeds. Each time radiation from the poles of the pulsar sweeps by Earth, a pulse can be detected. If you convert each of these pulses into sound, you can get a sense of the rotation speed by "listening" to the pulsar.
Not all pulsars have a known pulse width, so in that case, a value of 3 ms is assigned.
Young pulsars often rotate quickly.
Old pulsars slow down their rotation with age, and thus their pulse rate is slower.