The Auricle Acoustic Waveguide
Braeburn gave its horn geometry a name and used it across every model from 2012 to 2019. Stripped of the trade name, it is a short folded horn cut into a solid block.
What the name covered
The archive describes the part consistently: an “Auricle Acoustic Waveguide that amplifies the speaker in a stylish, all aluminium CNC unibody construction”. Auricle is the anatomical term for the outer ear — the visible, cartilaginous funnel that collects sound and directs it inward. The naming is accurate rather than decorative: the part does the same job in reverse.
A phone lying on a desk radiates from a slot a few millimetres long, usually pointing down or sideways. The waveguide intercepts that output at the slot, turns it through roughly a right angle, expands it, and presents it to the room from a mouth facing the listener. Three separate problems are solved by one piece of metal: coupling, redirection and aiming.
The three dimensions that matter
A horn is defined by its throat, its expansion and its mouth, and each answers for a different part of the result. The throat is sized to the source. The expansion governs how gradually the acoustic load changes along the path. The mouth sets the lowest frequency that will be loaded at all.
In a desk cradle all three are constrained by something other than acoustics. The throat must align with wherever the manufacturer put the speaker slot. The path length is limited by how large an object a person tolerates beside a keyboard. The mouth can be no wider than the base. A horn designed under those constraints is a compromise, and knowing which dimension was sacrificed explains the measured result.
Why it folds
An unfolded horn long enough to be useful at speech frequencies would be an impractical object on a desk. Folding the path lets a longer horn occupy a shorter housing, at the cost of a bend.
Bends are not free. At frequencies where the duct width approaches a quarter wavelength, a sharp corner reflects energy and introduces resonances that were not in the design. This is the usual reason a compact horn measures well across one band and poorly just above it. Generous internal radii matter more in a folded horn than any choice of flare law.
| Item | Value |
|---|---|
| Function | Passive acoustic horn; impedance matching and redirection |
| Throat | Sized to the device speaker aperture |
| Path | Folded, approximately one right-angle turn |
| Mouth | Forward-facing, limited by the cradle footprint |
| Material | Aluminium, machined as a unibody |
| Documented gain | Up to 8 dB, no power applied |
Working out where the throat has to sit
The aperture moves with every device
There is no standard position for a phone's speaker slot. Across the generations the Braeburn line served, the output moved between the bottom edge and the lower rear face, and its width changed with it. A cradle designed around one position does not transfer to the next device, which is why the line has a separate body per generation rather than one adjustable product.
How to find it on a device in front of you
Play a steady tone and move a fingertip slowly across the lower edge of the casing. The output drops sharply when the slot is covered, and the point where it drops furthest is the centre of the aperture. Two minutes with a fingertip establishes the one dimension the geometry must respect.
Why the gap matters as much as the position
A throat placed a few millimetres away from the aperture leaks. Sound escapes into the gap instead of entering the duct, and the loss is largest at the frequencies the horn was sized to help. A cradle that holds the device loosely, or one used with a thick case, gives back part of the gain the geometry earned — which is what the record means when it notes that the connector adapts to any case.