The Advantages of Floor Coupled Up-Firing Speakers

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Well it may not be that bad.

See the graph below that compares the filtered voice signal and a 24dB/Octave filtered white noise using the same FFT method.

I wonder if the noises at the top comes from the file's conversion to MP4 and back to wave?

Regardless, I found the sharply filtered white noise to be easy to locate.
 

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Good point!
I ran your file again with my steep filter. Still lots of junk up top. I believe that is because of the unequal power, as you say. There is a lot of energy around 700Hz in the original. If seen in linear amplitude instead of log, it sure looks different!

It was the Lowpass_24db_300Hz voice file that I ran.
 
Don't forget that a voice sample does not contain equal power at every frequency.

By the way, which sound files are we talking about? I posted a couple.

Me quoting Markus76
I totally I agree with Earl but nonetheless there is useful spatial information in signals lower 500 Hz. Find out for yourself with the following two examples of a low-pass filtered male voice:

Low-Pass (24 db) at 150 Hz (AAC, 2 MB)

Low-Pass (24 db) at 300 Hz (AAC, 2 MB)

It also becomes pretty obvious how important higher frequencies are to understand one word at all :)

Best, Markus
 
Hello,

It's not a surprise noise can be located even at low freqs. The reason is it has temporal variance. Sinusoidal do not have.

Temporal variation of the signal is reproduced more accurately the less the room messes the sound. That's why for a low freq localisation in a small rooms directivity of the source grows in importance.

- Elias
 
Hello,

It's not a surprise noise can be located even at low freqs. The reason is it has temporal variance. Sinusoidal do not have.

Temporal variation of the signal is reproduced more accurately the less the room messes the sound. That's why for a low freq localisation in a small rooms directivity of the source grows in importance.

- Elias
For clarification: So the room will reflect back higher frequencies than what hits its boundaries? Is that what you are saying?

IOW, what exactly is temporal variance? Does it mean that the later arriving signals will have less high frequencies perhaps d/t directivity variance?

thanks,
Dan
 
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I did some low passed white noise testing on my system. Panning the signal left-right-left-right, etc.

At 40Hz LP (steep) I really can't easily hear if it's left or right. At 60Hz LP I can tell without much trouble. Sure, it's not as distinct as a midrange frequency, but it's certainly there. So somewhere between 60 and 40Hz things blend together in my room/my system. With noise.

With a steady sine, I had trouble at 300Hz.
 
Then you shouldn't come here and discuss it unless you are willing to give the details. People will stop responding to you completely if you do that.

Well maybe people will stop telling what is the best use of my time. Some of my ideas are grounds for patents and I am no fool to just give them away without making sure they are open to the public to use (ie CC). If I didn't all I would be doing is giving my ideas away to the first person smart enough and with enough money to lock the rest of us out of that idea. Feel free to tell me when I'm wrong I wont be offended. But I don't like open ended guessing about what I am doing and sweeping generalizations about what can be accomplished.
 
On bass localization. I think I have found some situations where you will mis-localize frequencies lower than 80Hz. They are subtle though so I don't know if they are that big of a problem.

But for instance if you have a tuned kick drum panned like 25% to the left and say a bass with the same harmonics panned hard right I think my brain gets confused as to which harmonics the fundamental belongs to. You get sort of a localization in between the two instruments in the worst case but at times it sounds to me like the fundamental is in both places sort of stretched in length covering the area between them.

A few times I swear I have localized 30Hz and lower at the sub with certain programmed music because there is nothing but a sine wave down there and there is a complete lack of harmonic content - or it's so low I am not picking up on it.
 
:cop: graaf & markus. Keep on topic please. No personal arguments.

erased quotation from Floyd Toole wasn't "on topic"? :confused:

I ask because before typing it in again (I haven't it in digitalized form so I can't just copy and paste) I would like to know whether it violates forum rules

Can I ask Markus whether He tested "Beolab 5" speakers (or just gave them 5 minute listen somewhere) before concluding that they are "one of the worst" or will it be regarded as "personal argument"?

I would just like to know the rules. I desire to obey them.
 
Can I ask Markus whether He tested "Beolab 5" speakers (or just gave them 5 minute listen somewhere) before concluding that they are "one of the worst" or will it be regarded as "personal argument"?

Looks like you're allowed to ask. I don't know how you define "test" but if someone says "I once heard the Beolab 5" then this is no indication for a (double) blind test but an informal sighted listening session.

I listened to the Beolab 5 at the B&O shop in Munich, Maximilianstrasse. The speakers were set up symmetrically about 50cm from the front wall. I was sitting on a leather couch in about 3m distance. The room opens to a larger space behind the sofa. We closed all windows to minimize noise and calibrated the speakers. I had CDs with me that I'm very familiar with and listened about 45 minutes.
The sound was non-transparent. Very hard to listen through the recording and to follow single instruments. Localization was ambiguous. A huge "cloud" of sound, a creamy soup instead of a minestrone. The bass calibration was disappointing - there were still huge modal peaks, overall bass level was too low and a serious lack of energy below 50Hz (the speaker is advertised "EFFECTIVE FREQUENCY RANGE 20-20,000Hz").
 
an interesting patent and AES-paper:
Patent US4496021
AES E-Library: Loudspeaker Directionality and the Perception of Reality

what makes it interesting is not so much the "orthospectral tweeter" itself but some statements in the "background of the invention" section - see image attached

those statements seem to give basic theoretical explanation for Linkwitz's "wall effect"
see: ORION++

it is a widely held belief that reflections destroy transients and diffuse phantom images. Reflections must be avoided. Yet they are important for energy distribution in the room. This belief has been slowly changing (e.g. Moulton, Toole), but only for lateral reflections. The space behind the speakers has always been suspect for changing the sound unfavorably, and rightfully so. Almost all loudspeakers illuminate this space unevenly and sonically colored. I now also understand why flush mounted speakers sound off-the-wall to me. They completely lack rear wall reflections and thus important spatial cues.

One might postulate that the wall reflection will add a sameness to all sound playback because the listening room acoustics from reflections right close to the loudspeakers get mixed in heavily with the recorded acoustics. The exact opposite is heard. Recordings become more differentiated, the whole range from dead to wet acoustics is clearly perceived.
 

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This doesn't explain anything. The influence of reflections is not fully understood. Everybody is guessing and declares his own experience the truth. This dogmatic approach to small room acoustics is most evident in the history of control room design (see Jan Voetmann "50 Years of Sound Control Room Design", AES Convention Paper 7140).

Toole himself asks the right questions in his AES paper "Loudspeakers and Rooms for Sound Reproduction—A Scientific Review". There is strong evidence that number, spectrum, angle, level and delay of single reflections are the key. We just don't know yet what the important properties are and how to measure them.

Best, Markus
 
The influence of reflections is not fully understood. Everybody is guessing and declares his own experience the truth.
(...)
There is strong evidence that number, spectrum, angle, level and delay of single reflections are the key. We just don't know yet what the important properties are and how to measure them.

and from that it follows that various unorthodox approaches discussed in this thread are equally valid than eg. constant directivity waveguides and so on, doesn't it?
 
In the light of facts only one approach is reasonable: make the sound field in the listening space similar to the sound field of the original, whereas the original is the sound field of the mastering/mixing room. In my opinion only loudspeakers with high, constant directivity will provide such a sound field in domestic listening rooms that don't allow for major room acoustic optimizations.

How the optimal sound field should look like and how recording and mixing techniques would need to adapt is a different discussion.

Best, Markus
 
But with a constant directivity it is virtually impossible to make the first reflections the same as the direct sound. Since the bass will be omni and the treble directional the bass will always be reflected back at you before the highs and will not be the same spectral balance. An omni will make the reflection times shorter but remains roughly the same spectral balance regardless of which angle is reflected at your ear first.