What does the Audio Image Processor Do?
8
Imagine you are listening to a pair of speakers. If you turn off the left speaker, both ears
hear the sound from the right speaker. But because the left ear is slight farther away than
the right ear, it hears the speaker’s sound slightly after the right ear; about 300 miliSeconds.
This time difference is called the “inter-aural time difference” and it is the main thing your
brain listens for in order to tell where to place sound left-to-right.
But in headphones if you turn off the left channel, only the right ear hears the sound. In head-
phones, if there is any sound that is only in the left channel, or only in the right channel, then
only that ear hears the sound. This is not natural, and you brain becomes fatigued trying to
figure out where sound is coming from when only one ear is hearing it. This tends to create
an audio image that is a blob on the left, blob on the right and a blob in the middle.
HeadRoom amplifiers cure the problem by allowing you to cross-feed a little of the left and
right channels across to each other through a short time delay using the processor switch.
The usefulness of the circuit varies depending on what type of recording you are listening
to; mono and binaural recordings need no processor at all. Old studio recordings that have
instruments panned hard left or right, benefit greatly from the processor. Live and classi-
cal recordings miked from a distance benefit somewhat less, and can often be listened to
without the processor quite comfortably.
The processer switch in HeadRoom
amplifiers allow you to cross-feed a
little of the left and right channels
across to each other through a short
time delay.
