Added in firmware version v1.2.0 - see firmware page for how to update.
Binaural mode only works with stereo headphones, not with the speaker output. It makes tones sound as though they are coming from different positions based on their frequency.
Settings for this can be found in the "Binaural mode" section of the menu.
The centre frequency and bandwidth settings control the frequency range over which the position varies. Tones outside this range stay in a single position and do not move based on frequency. For example, in low-high mode, all frequencies below the lower edge stay fully on the left, and all frequencies above the upper edge stay fully on the right.
There are three modes: Low-high mode: lower frequency tones are on the left and higher frequency on the right.
Near-far mode: tones near the centre frequency are on the left, tones further away from it are on the right. Narrow-wide mode: tones less than half the bandwidth from the centre frequency are fully on the left, other tones are fully on the right. Like near-far mode but with a sharp cutoff at the edges, instead of a smooth change over the entire bandwidth.
The "linear amplitude scale" setting alters the way in which the amplitude is adjusted:
On: amplitude is linearly scaled between mute and normal in each headphone, based on frequency.
Off: even when positioned fully to one side, tones are still audible (but quieter) in the other headphone.
The default value of 'off' is closer to real life so should give a more accurate 3D effect, but 'on' may be worth experimenting with. For example, with near-far or narrow-wide mode focused on a narrow bandwidth around a single CW signal, turning linear amplitude on means the desired signal will be audible in the left ear only, and all other stations audible in the right ear only.
By default, the speaker output runs off the same data as the left headphone, so will be affected if binaural mode is on, but will not give any impression of varying sound locations. The speaker output can be switched to run off the same data as the right headphone in the "Output settings > Speaker channel" setting.
There are 6 memory slots available, plus a power-on defaults slot, where binaural settings can be saved and loaded in order to quickly switch between them.There are also a few presets with recommended values to try for CW. However, the settings that work best will vary depending on operating mode, band conditions, and personal preference, so do try adjusting them. To adjust the relative volume of left and right audio, or to swap left and right, use the "L/R balance" or "Swap L/R" options in the "Output settings" menu.