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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: Again confused posted by Belgarchi on July 15, 2012 at 17:59:08:
Hi,
> The power response is NEVER, EVER eared by a listener!
This goes against a fairly large body of work in resarching the subject, including but hardly limited to Floyd E'Toole's work so idolised by villastrangiato.
Now if you have made research that suggests the contrary I would be keenly interested to read more about it. Otherwise you may wish to peruse some of the links I suggested to villastrangiato for some remedial reading.
> A human being, despite quantum mechanics theory, is in practical,
> actual life at one point in space at a given time.
> I don't even agree with the averaging of frequency response at
> different places.
The problem is not where the human being is, but how the human hearing works (e.g. Haas et al) and the location where the human being listens to music on a HiFi.
The only place where the off axis response of the speaker has no bearing on the direct on-axis sound would be dozens of meters up in the air with both speakers and human suspended in free space.
Ignoring how uncomfortable and impractical such a "listening - non - room"
, it would deliver a pure free field.
In reality of course we tend to be quite surrounded by sound reflective surfaces, known to those skilled in the art as "Walls" and "Floor" and "Ceiling".
> What you ear is what a measurement microphone records at one location.
You seem confused. The Human hearing is remarkable for how it operates precisely in a way that remarkably nothing like a microphone.
> you can move, and then the frequency response will change, and can
> be measured by the same microphone at the same location. But you
> will never ear an 'average'.
You are missing a crucial point. For a certain time span (the so-called Haas Window) will integrate both first arrival and reflections into "one stimulus".
The first arrival dominates the perception of direction, the integrated sound power dominates the perception of loudness. Any sound arriving outside the Haas window n will be percieved as "Echo".
In terms of distance the Hass window is around 7 - 14m...
> As for the 'power response', it is theoretical (energy spread in all
> directions, that will NEVER reach your ears in the same amplitude
> versus frequency balance, 'thanks' to differential ansorption and
> phase changes).
The energy not directly radiated towards the listener will reach the listeners ears inside rooms, however it will reach it delayed.
And you are right, if there is much absorption (as opposed to diffusion) in the room this will alter the tonal balance of the reflected sound. This in one of the reasons why excessive absorption is not a good idea in listing rooms. Absorbtion can only be used if offers equal absorbtion across the rull range of frequencies.
> Now, you could challenge this using quantum mechanics.
Why? It is not necessary to do so.
Simple conventional acoustics and human hearing analysis suffice to completely reject your position and to confirm that indeed in acoustically small rooms (like recording studios, living rooms etc.) the perception of loudness (and hence frequency response) is dominated the speakers off axis response (which is often rendered as "power response".
Interesting this "power response" gig is also one of the reasons why both "baffle step" and "Floorbounce Notch" do not exist in real systems and real rooms.
The "floor bounce notch" as such has a frequency that is caused by delay, however the delay of the many LF reflections that will be present and reach the listener where they will be integrated will have many different "notch" frequencies. As the direct on-axis sound only contributes a small fraction to the total sound power there is no deep notch.
Similarly, as the "Baffle Step" only exists on axis, but not in the integrated sound (incidentally a small amount of correction, but less than 3dB may be desirable BTW, once all interactions are considered), so if you compensate the baffle step what you actually get at the listening position is a 6dB Boost, something that is trivial to confirm using Pink Noise and a simple spectrum analyser.
Ciao T
Thor
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?
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Follow Ups
- RE: Again confused - Thorsten 23:41:37 07/15/12 (0)
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