Singing time
From Tardis Wiki, the free Doctor Who reference
The singing time was a point in a Chimeron's growth when it gained control over its singing. It enabled it to decide what form and frequency it used. The singing time occurred when a young Chimeron grew into a princess.
In 1959, a Chimeron princess was able to defeat the Bannermen after the singing time had occurred. The noise was amplified by a speaker, causing disarray. (TV: Delta and the Bannermen)