One possibility for "hearing" ULF is sympathetic vibration. A sound with one vibratory
mode can induce a different sound in a table (or ear). As the molecules in these
substance vibrate higher and lower harmonics can be induced, it all depends on the
particular molecular dynamics. For example, it has been observed that some
people "hear" tables hum during geomagnetic storms - this is a sympathetic
vibration. There really is no reason to think that physics does NOT exists which
would allow "sensitives" to hear sounds related to earthquakes which instruments
would not be able to "hear" because the instruments would not be capable of producing
the sympathetic vibrations.