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In the Forum: Horn-Loaded Speakers
In the Thread: Battling stupid Horn Criticism as a concept
Post Subject: Material is not specific enoughPosted by rowuk on: 11/23/2012
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Horns are of course some kind of band pass filters with different kind of ripples at lover cutoff and beaming at upper cut off, according to horn type. Maybe it should be added that contributing to the horn sound idea, is that the sound also depends on the material of the horn wall, flutes for instance are made of either, brass, silver or gold with a reason other than cosmetics. |
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The material in acoustic instruments is manufactured in a different way. The mass of the instrument is very low compared to the acoustic power. Generally the instruments have braces - some to conduct sound - like with a feedback loop, other braces damp sound. Also the material is hardened and annealed during the construction process. This shapes the overtone series and thus the timbre. Eve as the instruments get older, the vibration during playing changes the temper (hardness) of the material. The sound changes/matures like a good wine. Speakers are built more massive compared to the acoustic output power. They are often built from a much lossier material with much less change over age too.
Different materials in wind instruments help the player find a sound that better matches what is in their heads. This reduces the amount of energy required to become "one" with the instrument and thus frees up energy for the creative process. In the hands of a weak player, material considerations are generally not audible/useful.
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Then there are flutter echo like bathroom sounds that horns also sometime produce, especially if they have a glossy surface.
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Properly designed Horns used within a sensible pass band are too short for any type of "flutter". Flutter type echos need to be out of the early reflection period (>20ms) for our ears to do anything with them. Our brain has no resolution for early reflections - they simply confuse the moment by changing our perception of pitch, sonic color and location of the sound. This is well documented in much of the audio engineer literature. The worst that could happen on a badly designed horn working out of the proper pass band would be cancellation due to phase effects/standing waves in the horn. This would be most audible on horns that are too short or with improper termination at the mouth. Due to the improper termination, a part of the sound is reflected back into the horn (desirable for resonant wind instruments) and sets up a standing wave that has NOTHING to do with the hardness or gloss of the surface.
I think that there is a big misunderstanding when it comes to wave propagation. The soundwaves in fact move at very high speed, the air molecules are essentially standing still. Sound is passed by one air molecule bumping into the next - the stationary air does not care if a surface is hard, neither does the sound wave. If the horn contour is used in a way not complementary to its contour/length, reflections can cause phase/amplitude artifacts. I have heard fine sounding hard glossy horns. My own research has actually confirmed to me that absorption/diffraction is generally useful when you are trying to correct for bad design and less necessary when the design is good.
When it comes to controlling the last couple of % of sound quality, we need a reference, as different can but must not be better or worse. It just depends on the manipulation of the artisan. There are so many things happening in any acoustic instance that it is difficult to say with certainty what causes a specific audible artifact.Rerurn to Romy the Cat's Site