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Stereo imaging in audio is always an interesting topic amongst audiophiles. Join us this week as we are happy to share a snippet from this topic from the notebook of Art Noxon, PE Acoustical. Enjoy!

Concepts by Art Noxon

High-end audio sound reproduction has two functions to perform:

1. Musicality
2. Imaging

A speaker generates a sonic image that overlays itself, an image that seems at the speaker; you can look right at the speaker and see exactly where the sound is coming from: the speaker driver. Sometimes we even say we are sonically looking down the throat of the driver, more often right down the throat of the horn.

Roughly speaking imaging is something we experience because we have 2 ears and a head. If sound comes from straight in front of us both ears hear the same sound wave at exactly the same time.

If we turn our head or the speaker is off to one side one ear hears the speaker better than the other. That means the speaker is off to the side of the ear that hears the better sound. The weak ear is in the acoustic shadow of the head and the sound is quieter. Also the weak ear hears the sound after the strong ear hears it.

The timing of the wavefront as it crosses past the two ears influences our perception of where the sound comes from. Head shadowing as well. Both timing and head shadowing are wavelength dependent relative to the size of the head. Directionality works for wavelengths less than 4x head diameter, about 2 feet or 500 Hz.