Acoustic switches are required by law for all offshore rigs off Brazil and in Norway's North Sea operations. BP uses the device voluntarily in Britain's North Sea and elsewhere in the world as do other big players like Holland's Shell and France's Total.
In 2003, newly reconstituted Minerals Management Service genuflected to the oil cartel by recommending the removal of the proposed requirement for acoustic switches. The Minerals Management Service's 2003 study concluded that "acoustic systems are not recommended because they tend to be very costly." The acoustic trigger costs about $500,000.
It's time to pay the Piper!!!