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Speaker Asylum General speaker questions for audio and home theater. |
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Speaker Asylum General speaker questions for audio and home theater. |
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In Reply to: RE: Relevant loudspeaker tests posted by Inmate51 on July 11, 2014 at 13:05:49:
“With current "practical" technology, we cannot reproduce a musical instrument sound via a recording and subsequent reproduction system. It cannot happen.”
That may be true of home hifi given the self imposed boundaries for that market and the way most popular recordings are made but it is not at all true when those constraints are removed.
It is entirely possible to reproduce an event such that one is fooled into believing it is a live event or, that there is a person standing in front of you talking to you. It is possible to even make a voice or music sound like it’s coming from 20 feet away when the source of sound is actually 500 feet away.
A couple things you assert are true / partially true and not true.
When instruments are played outdoors, what arrives at your ears is sound that has traveled directly form the instruments to your ears, plus a small amount reflected off the ground. If you listen to instruments played in an anechoic chamber, part of why it sounds un-natural is all the ground reflections are gone and we are very used to hearing and ignoring those as we know nothing else in our lifetime of hearing..
Outdoors we have the best stereo imaging, best ability to localize the source location and none of that has anything to do with lateral reflections like a rooms walls produce.
What is lacking is a way to capture that live stereo event as we hear and our brain composes an image which is in one point in space. As soon as one has two or more microphones, one is getting two or more sets of time information and real stereo is lost.
Notice is all the boring discussion of Generation loss recordings; it is ALWAYS using one measurement grade microphone which preserves time. Measurement microphones do not impart spatial or frequency response effects or at least they are VERY VERY small compared to most microphones used to record which do have directional properties, do not behave the same across the entire band and many chosen because of a “sound” of their own.
Also the assertion that “This then is "reproduced" through a single point via a loudspeaker which has a singular radiation pattern, and re-radiates the single-point sound into another room!” is largely wrong.
There are extraordinarily few loudspeakers that are an acoustic point source, an acoustic point source being something that radiates from a single point in space and time over the entire bandwidth as Heyser described it.
Rather, most speakers are multi-way systems and radiate portions of the spectrum from different acoustic locations and with crossovers, are dispersive in time and so cannot reproduce the waveshape of the input signal over a broad band. These multi-way systems radiate an interference pattern instead which can be seen in a polar response measurement as a series of lobes and nulls, or heard first hand outdoors playing pink noise when you move around the speaker.
Even a single crossover less driver can radiate an interference pattern when there is diffraction at it’s edges which re-radiate from a new point in space and time. Put a small / good full range on a large flat baffle, play a soft voice and it will be harder to “hear” its physical distance from you and like an ESL63, the voice sounds like it’s coming from somewhere behind the actual source, while speakers that radiate an interference pattern are EASY to localize the depth when your eyes are closed.
When part of a stereo, when playing that same voice through both speakers the sources that were easy to localize in depth, now stand out as a right and left source in addition to the desired mono phantom while the ones that are hard to localize in depth, disappear and ideally are inaudible as a right and left source.
Yes the room alters what the speaker produces, how much it does, depends on it’s location in the room wrt the walls and governed very strongly by the loudspeakers directivity. The greater the energy is within the pattern compared to outside it, the large the area is where the direct signal dominates, the less effect the room has harming the original signal fed to the speakers.. As a room and listening distance grows, this is directly related to intelligibility. It is critical for the reflected sound to arrive “enough” later such that it doesn’t harm the image, and that is called the ITG or initial time gap. Unfortunately for home hifi, the directivity is strongly related to physical size as one can’t change the wavelength’s involved to have a higher SAF and so one is stuck with a lot of short delay room sound as well.
“Given this, it's amazing that stereo systems sound as good as they do - even if they don't sound like real instruments!”
Well that’s true, sort of like being constrained to the speed and market limitations of a “cost is no object” tricycle but entirely untrue once free of those limitations.
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Follow Ups
- RE: Relevant loudspeaker tests - tomservo 07:32:17 07/12/14 (1)
- Agreed... - mkuller 11:07:44 07/12/14 (0)
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