Frequency-modulated acoustic lock

{k t{Infobox Object The Frequency-Modulated Acoustic Lock was a device that appeared in The Rings of Akhaten. It was presumably a lock that could be unlocked by a sonic frequency, although a constantly changing one as a security measure.
 * image      =
 * aka        =
 * type       = Lock
 * origin     = Unknown
 * made by    = Unknown
 * used by    = Sun-singers of Akhet
 * first      =
 * only       =
 * appearances =

Frequency-Modulated acoustic lock