Based on the instrument invented by Leon Theremin Thereminvox lets you create that classic eerie sci-fi sound.  Like the original instrument, there are two continuously variable controls; volume and tone. Volume is controlled by moving your left finger up and down while tone is controlled by moving your right finger(s) left and right. The tone can be raised or lower by either moving your right finger up or down or by opening your two right fingers to simulate opening and closing your hand, depending on which mode of play is selected.

Theremins are often played with vibrato so Thereminvox has an auto vibrato feature. You select the the rate and extent of the vibrato and Thereminvox takes care of the rest.

The range of tones can be selected by the user, and is limited only by the sounds your iPhone is capable of producing. Unlike the original instrument which is notorious for a lack of feedback other than the actual sound produced, Thereminvox gives you both a frequency display as well as a tuner displaying the nearest note and graphical display showing if you are flat or sharp.

The user can also select the key to play in. The key selected has no effect on the sound produced, the Thereminvox can produce a tone across it’s entire frequency range. The selected key only affects the grid overlay and the tuner.

Volume is controlled by touching the volume control on the right. Move your finger up for louder and down for softer. If you aren't touching the volume control Thereminvox will not make a sound

Tone is controlled with one or more touches of the tone control. Move the touch right and the tone goes up, left and the tone goes down. If you aren't touching the tone control tone goes to the low tone set in configuration. The vertical lines show where each note in your selected key is. Use the tuner at top to make sure you are hitting the right note. The tone can be modified in one of two ways depending on if multitouch is enabled.

In single touch mode the vertical lines represent the tone at the green base line. The horizontal lines represent half tone steps up or down off the base note.

In multitouch mode the tone is selected using two fingers (thumb and index finger works best). The vertical lines represent the tone when the fingers are together. Raise the tone by moving your fingers apart. The horizontal lines show the distance apart your fingers need to be to raise the tone 1,2, and 3 half tones.


The selection of key controls how the grid overlay is drawn and what notes are shown in the tuner.

The frequency range is selectable based on note and octave of the low frequency and the high frequency. Although there is no limitation on how big of a range that can be selected in practice anything much bigger than 2 octaves makes it impossible to select individual notes. The test buttons allow you to hear the selected low and high tone.

With multitouch enabled use two fingers to control the tone (thumb and index finger work the best). The tone can now be raised by moving your fingers apart. The matching colored lines show the distance to raise the tone 1/2 step.

With vibrato enabled the tone is automatically varied based on the Rate and Extent selected. Rate is the rate of change in frequency in Hz. and Extent is the amount the frequency in changes in halfsteps