Foam earplugs and hidden distortion in horns
Horn-loaded loudspeakers can make low-level problems difficult to notice because their efficiency, controlled directivity and strong upper-midrange presence tend to dominate the listening impression. A hard bass note may sound impressive, while a buzzy harmonic or unstable note just below it slips beneath the surface.
Foam earplugs offer a revealing second condition by reducing high-frequency information and lowering overall loudness. In Sunship Audio’s Berlin demonstration room, changing between protected and unprotected ears can help listeners separate firm horn character from unwanted compression artefacts, cabinet resonance or crossover coloration.
What foam earplugs actually change
Foam plugs do not expose distortion directly; they change what the ear can mask. Their strongest attenuation is usually in the upper mids and treble, which can make roughness around vocal formants, cymbal texture and compression-driver breakup more obvious.
Because the ear receives less high-frequency guidance, it becomes more sensitive to changes in bass definition, midrange thickness and timing. A note that initially sounds full may reveal an uneven decay once the bright edge is removed.
Fit remains crucial. A poor seal can produce an artificial sense of extra bass because middle frequencies are filtered unevenly, while a tight seal may make a quiet room seem unnaturally dead. Listeners should therefore use the same type, fit and insertion depth for repeat comparisons.
Why horns reveal particular artefacts
A horn loads a compression driver efficiently, giving a horn system considerable output from a relatively modest driver. That efficiency also makes the quality of the horn, throat, waveguide and driver coupling important. Small discontinuities can create tonal peaks or uneven response around the crossover region.
At higher levels, compression drivers may develop harmonic coloration or intermodulation that is hidden in normal conversation. Passive crossover components, impedance behavior and cabinet reflections can add their own layers, so a perceived buzz is not automatically evidence of a faulty horn.
Sunship Audio’s guide to low-frequency extension explains how horn geometry interacts with the intended frequency range. This matters during earplug comparisons: apparent bass distortion may actually sit near a horn’s transition point or reflect interaction with the time-aligned passive crossover.
Open-ear and protected-ear comparisons
The same passage should be played at a moderate, repeatable level under both conditions. The useful question is whether the perceived character follows the music consistently rather than becoming harsher as fatigue sets in.
| Listening condition | Easier to perceive | Main limitation | Useful comparison |
|---|---|---|---|
| Open ears | Treble detail, air and high-frequency attack | Bright artefacts can mask bass problems | Establish the speaker’s normal tonal balance |
| Foam earplugs | Bass texture, harmonics and decay | Excessive dullness may imitate coloration | Check for roughness below the treble |
| Open ears after protected listening | Recovery from earplug adaptation | Immediate contrast can seem exaggerated | Make the final tonal judgment |
| Repeat with another track | Consistent behaviour across content | Different programme material may skew judgment | Confirm any suspected resonance |
A grille buzz, loose fastener or reflection may respond differently to hats, voices and drum cymbals. Repetition helps distinguish a stable fault from programme-dependent texture.
Listening for horn and cabinet faults
Listen first for changes in harmonic character. A clean horn should not make a sustained note suddenly acquire a reedy edge, while a reproduced voice should retain stable consonants without a sandpaper-like outline.
Next, examine the decay after each sound stops. Heavily braced birch-plywood cabinets are intended to remain rigid, but cabinet resonance, standing waves and port air noise can lengthen or colour the tail. A foam-plug comparison can make that extra energy easier to hear.
Avoid interpreting every difference as distortion. Earplugs alter the entire spectral balance, and the Berlin room supplies a fixed reference that will differ from an Australian dealer room or a home built on a concrete slab. The relevant finding is a repeatable change associated with a horn, driver or cabinet behaviour.
Why the demonstration environment matters
Sunship Audio maintains a dedicated listening and demonstration room in Berlin, giving visitors a controlled way to compare its custom systems. That control is valuable because custom horn speakers, passive crossovers and cabinet dimensions are often commissioned after an initial dealer consultation.
Australian buyers commonly encounter specialist hi-fi dealers in Sydney and Melbourne, with listening events also appearing through hi-fi groups and clubs in Brisbane, Adelaide and Perth. Asking to compare an unfamiliar design with foam earplugs is more useful after establishing the normal presentation with the dealer’s familiar programme material.
Local rooms often present a different challenge. Many Australian homes combine concrete slabs, brick walls, tiled surfaces and open-plan living areas, all of which can increase low-frequency boundaries or reflections. A dead-quiet listening session—an arvo of careful playback, as some enthusiasts say—still begins with the room itself.
A repeatable foam-plug listening routine
Use a short, familiar track rather than a dramatic demonstration recording. Keep the volume steady and avoid changing equipment between conditions.
- Start with open ears and note the balance, bass definition and apparent loudness.
- Fit clean foam plugs consistently and replay the same passage without altering controls.
- Listen for buzz, hollow tones, unstable decay or unevenness around voices.
- Remove the plugs, allow a short adaptation period and compare the same moment again.
- Test the suspicion with a second track containing different harmonic content.
- Confirm important findings through dealer measurements or a longer home audition.
Custom loudspeaker purchases in Australia often involve an Australian-dollar quotation, deposit and specialist freight arrangements. That process makes early comparison essential, while later room calibration and installation can be as influential as the product itself.
Hearing character without manufacturing faults
A good horn should remain composed without sounding lifeless. With open ears, its dispersion and treble detail should feel natural; with foam earplugs, the underlying notes should remain articulate rather than turning thick or smeared.
For disciplined note-taking, critical listening notes can help separate immediate reactions from repeatable observations. The most persuasive result is identical across tracks, volume levels and repeated open-ear checks: firm extension, coherent midrange and a clean decay.