174 Hz is the lowest of the extended Solfeggio frequencies — a set of tones that builds upon the original six-note scale rediscovered from medieval chant. While the original Solfeggio (396–963 Hz) was derived from the hymn to John the Baptist, the extended tones at 174 Hz and 285 Hz were added by researchers who identified them as harmonically connected to the core scale.

In sound therapy, 174 Hz is called the "Foundation Frequency" because it is believed to work on the body's most fundamental physical layer. Practitioners associate it with pain relief — particularly in the lower back, legs, and feet — and a deep sense of physical security and safety. It is often the starting point in frequency-based healing sessions, establishing a baseline of stability before moving to higher tones.

The frequency produces a warm, grounding tone that sits comfortably in the lower-mid range of human hearing. It is gentle enough for extended listening and makes an effective base layer in meditation or relaxation sessions.