Modern IMO regulations specify ships' horn frequencies to be in the range 70–200 Hz for vessels that are over in length. Traditionally, the lower the frequency, the larger the ship. "Queen Mary 2", being long, was given the lowest possible frequency (70 Hz) for her regulation whistles, in addition to the refurbished 55 Hz whistle on permanent loan. Fifty-five Hz is the "A" note an octave above the lowest note of a standard piano keyboard. The air-driven "Tyfon" whistle can be heard at least away.