55 Hz is the open third string of a bass guitar and a double bass, three octaves below the 440 Hz reference A, so it divides into 440 exactly.
Which note 55 Hz is at other reference pitches
“In tune” depends on what A4 is tuned to, so the same frequency is a slightly different distance from the nearest note in each tuning.
| Reference | Nearest note | That note | 55 Hz is |
|---|---|---|---|
| A4 = 440 Hz · Standard (ISO 16) | A1 | 55.00 Hz | exactly on it |
| A4 = 432 Hz · “Verdi” pitch | A1 | 54.00 Hz | +31.8¢ |
| A4 = 442 Hz · Orchestral | A1 | 55.25 Hz | −7.9¢ |
| A4 = 415 Hz · Baroque pitch | B♭1 | 54.96 Hz | +1.3¢ |
Octaves of 55 Hz
Doubling a frequency raises it an octave and halving lowers it one, so these all have the same note name.
Harmonics of 55 Hz
A real instrument playing 55 Hz also sounds whole-number multiples of it. The first eight, and the notes they fall nearest:
| Harmonic | Frequency | Nearest note | Off by |
|---|---|---|---|
| 1 | 55.00 Hz | A1 | 0¢ |
| 2 | 110.00 Hz | A2 | 0¢ |
| 3 | 165.00 Hz | E3 | +2.0¢ |
| 4 | 220.00 Hz | A3 | 0¢ |
| 5 | 275.00 Hz | C♯4 | −13.7¢ |
| 6 | 330.00 Hz | E4 | +2.0¢ |
| 7 | 385.00 Hz | G4 | −31.2¢ |
| 8 | 440.00 Hz | A4 | 0¢ |
Period and wavelength
One cycle of 55 Hz lasts 18.182 milliseconds; in air at 20 °C, where sound travels at about 343 metres a second, one wavelength is 6.24 metres.