Controllers have pop-up windows with various choices of standard messages for altitude changes, frequency changes and some re-routings.

WSJ: Texting While Flying: Help for Pilots

On both sides of the Atlantic the frequency of price changes varies enormously.

ECONOMIST: Economics focus

To avoid detection it changes frequency almost every day.

ECONOMIST: Thailand's red-shirt opposition

According to Capita, who dispute the phrase "lie detector test", "VRA analyses, in real time, changes in voice frequency" which are then assessed by "trained operators" to identify possible bogus claimants.

BBC: Councillor resigns over 'lie detector' fears

They are the same organizations that have forgotten New Orleans and forgotten to follow up on contractors who aren't fulfilling their responsibilities there -- important not only for the people of NOLA, but also for setting a precedent for the victims of Sandy, and of the many storms to come whose frequency and severity will rise as our climate changes.

CNN: Model Cameron Russell: I get what I don't deserve

Though these changes can go unnoticed by a person with a disease, relatives and friends more often pick up on it, but a computer algorithm that detects nuances of speech and subtle changes could detect abberations with much greater frequency.

FORBES: New Software Can Diagnose Parkinson's Disease Simply By Listening To Your Voice

One photon in a million comes away with a different frequency from the one that it arrived with because it changes the structure of a chemical bond in one of the plastic's molecules.

ECONOMIST: Recycling

The focus recently has been on trying to pin down the details of the neutrino's split personality: How far it travels before it changes from one type into another, and which types change into which and with what frequency.

NPR: Neutrinos: A Cursed Subatomic Particle?