220 Hz tone

An octave below the tuning standard

Few tones are as musically cooperative as 220 Hz: it is A3 with zero cents deviation, precisely half of the 440 Hz concert standard. Played as a sine wave it sounds warm and open, sitting in the lower-middle range where cellos sing, violas anchor, and tenors bottom out.

Because it divides concert pitch by exactly two, everything about it feels settled. Octave-listening exercises start here naturally — play this page, then open the 440 Hz tone in a second tab, and alternate to burn the octave relationship into memory. Interval students return to this pair for years.

Where 220 Hz shows up

Guitarists meet 220 Hz as the open A string only an octave lower in spirit — the fifth string rings at 110 Hz with a strong 220 Hz overtone coloring every strum. Orchestral players hear it inside the oboe A they tune to, and choir directors use it as a comfortable low reference that does not strain untrained voices.

Studios use it as a crossover checkpoint too: it sits above subwoofer territory but below the presence range, so if 220 Hz sounds thin, the high-pass filter is set too aggressively or the monitors lack midrange body. Producers checking mixes on small speakers confirm this tone survives before trusting the low end.

As a test signal it sits in the flattest part of most speakers response, making it ideal for channel-balance checks: pan left, then right, and any loudness gap you hear is the room or the device, not the tone. It also anchors the multi tone generator octave-stack preset as the bottom voice.