Mackie MR8 Mk3 Active Studio Monitors:
Frequency Range: 35Hz - 20 kHz
The lowest Sine Wave Frequency I can measure, using GVST's G-Tune:
25.96Hz (G#)
The Lowest Frequency output from Monitors:
27.5Hz (A)
I cannot HEAR this frequency, but at full output volume, 27.5Hz creates vibrational stimulation of the doors & windows of my Apartment.
The most common frequency range of human hearing:
20Hz - 20kHz (but varies widely between individuals)