The engineer's view

A note name is only half the answer at the desk. Under every Hz → Note result PitchSense also shows where that frequency sits on your EQ and how long its wave is.

Band and fader

• ISO band — the nearest centre frequency of the standard 1/3-octave series (ISO 266): 20, 25, 31.5, 40 … 16k, 20k Hz. These are the numbers printed above the faders of a graphic EQ.
• GEQ fader — which fader that band is on a 31-band graphic EQ, counted from 20 Hz on the left.

Example: 315 Hz is D♯4, 21.4 cents sharp. It sits on the 315 Hz band, the 13th fader of 31. The note helps when you hear the ring as a pitch; the fader is what you pull.

A 1/3-octave band is 400 cents wide, so a frequency between two centres belongs to whichever is nearer on a musical (logarithmic) scale.

Wavelength and quarter-wave

• Wavelength — the speed of sound divided by the frequency.
• Quarter-wave — a quarter of that: the path difference at which two copies of the same frequency cancel, and the distance that matters when you space subs or a sub and a wall.

The speed of sound depends on the air temperature, so the result states the temperature it was worked out for. At 20 °C sound travels about 343 m/s: 100 Hz is about 3.43 m long, and its quarter-wave is about 86 cm.

Kick and sub to the song key

Pick the key of the song and the table lists the low notes that belong to it, each with its frequency and a play button. Use it to tune a kick sample, an 808 or a sub so its fundamental sits on a note of the song rather than between two.

The low octaves are where a phone or laptop speaker plays little or nothing: listen on headphones or the PA, or read the Hz and tune by the numbers.

Related

• Getting started — the converter, the A4 reference and playback.
• Name a note from the microphone — name a ring from the microphone and keep a list of the rings you found.
• To find feedback automatically, SpectraSense listens for it and shows the band too.