home j h h l . n e t home

Line Hum 1.0

The noise you cherish is available for you to realitize your tracks!
Line Hum 1.0 will soon be now available the app store.

Line Hum is only available as an Audio Unit generator and effect. You need to use an Audio Unit host to enjoy Line Hum. To install it, though, means you have to run the actual app at least once. It will run nicely on M1 Mac Os as well.

Line Hum Icon
Line Hum will leave you groundless with familiar noise.

Big version:
Line Hum UI
Small Version:
Line Hum UI

Line Hum adds that missing "something" to your track: the sound of an ungrounded audio cable. It's an Audio Unit, so it must be run in an Audio Unit Host. There are a number of controls to give it just the right amount of Hum, and it can be set to 60 Hz (USA), 50Hz (EU and UK), or whatever.

  • Want to change the frequency (Kenneth)? Just tap on the number to set the frequency of the Hum. A pitch keyboard will come up:
    Line Hum Freq Board "60" and "50" are presets for 60.0 and 50.0 Hertz. "C" is "Middle C" (523.25113 Hz), which is also available as a preset. You can retune it either with the flat (♭) and sharp (♮) keys or up and down an octave with the ↓ 8 and ↑8 keys. Add or subtract 1 Hz with the -Hz and +Hz buttons. These transpositions also work for any frequencies you put in there manually.
    Otherwise type in more digits and decimals. Backspace with the back arrow (◀) button, clear it with the "CLR" button, and Confirm with the "✅" button, or Cancel with the "❎" button. You can also just pull the screen down to leave it in the state it's in. The "❓" will pick a random frequency within an octave near what it is now.
  • Line Hum frequency setter used in two instances

    You can save any pitch you like with the "down arrow" button, and restore it with the "up arrow" button. This goes for ALL currently running instances, so you can transfer it where you want and then change it - and even survives your session!

  • "Shape" controls the timbre of the Hum. The far left is a simple Sine wave. It adds and removes harmonics as the slider is moved to the right.
  • "Jitter" adds some instability to the frequency of the hum, and adds a little stereo instability.
  • "Mix" controls the mix between incoming signal and the Hum. All the way to the left is "No Hum, All Signal", to the right is "No Signal, All Hum".
  • "Ring" uses the Hum as a ring modulator modulating the signal's audio. It sounds best when the Shape is a simple Sine.
Now for some more details on the controls and settings.

First of all, here's how the controls work! I was very unhappy with the usual switches and sliders, so these are a little different!

  • Choice Buttons are just like buttons, but act a bit like pickers and radio buttons. They show the current setting in large, obvious type and the next choice underneat in smaller type. They may optionally have icons as well for each state. If they shrink to a small size, it skips the text and just shows the icons.
  • Numericals are a lot like sliders, but have more precise control. Touching down anywhere and moving left-right just a little will move the value just a little. The further you go, the more it will add to or subtract from the current value. Up and Down do the same, but usually with bigger jumps. You can get very precise by tapping the right side (to increase by one "unit") or the left side (to decrease by one unit). Holding down and not moving at either end for 1.5 seconds will set the value to the maximum or the minimum for that control, while touching in the middle and not moving for 1.5 second, and then lifting will reset the Numerical to a default value.
Got it? These new controls solve a number of UI problems like "Is the button label its current state or what it's supposed to do and why do I have to choose between them?" and "I can NEVER get the slider to be the value I want!".


Line Hum can also listen for MIDI (omni channel, monophonic). If it's listening to MIDI, it retunes itself to a Note On, transposing relative to the frequency setting as if that were MIDI middle C (note #60), with its velocity controlling the Mix. Setting it to other frequencies will cause it to stay in tune. Note Off sets the Mix to "No Hum, All Signal".

Pitch Bend is supported. By default it bends two semitones, but will obey the RPN pitch bend size message to reset it. Controller 1 (the control wheel, usually) controls the Ring Modulation.

Line Hum's AU parameters can be controlled by an external source, which can add life and surprises to your Hum. You can also run several copies of Line Hum in your AU Host app.

Line Hum is only available as an Audio Unit effect. You need to use an Audio Unit host to enjoy or be annoyed by Line Hum.

Here's a nice session with two Line Hums being controlled by MIDI, and one extra adding a nice modulated 60 HZ ring mod fuzz

That sounds like this:

Fun stuff! Because it's an Audio Unit, you can fill your AU Host with hums in serial and parallel combinations. A fun trick is to set the modulating frequencies just a little bit apart to get flanging and chorusing. A little Jitter is also good in your modulations. Go for it!
credits and contacts

Line Hum is by the author of the highly praised synthicity itself, SrutiBox, Droneo, Enumero, PolyHarp, AUMI, and more!

Line Hum collects no data whatsoever. See the privacy statement.
• Available in the iTunes App store
• Questions? Write to Line-Hum "at" jhhl.net, or go to the contact page
• Read about my iPhone development in this blog


© 2022 Henry Lowengard

iPhone home
© 2011-22 Henry Lowengard. iPhone, iPad, iPhone touch © Apple