aren't most measurement microphones omni?
sorry i don't see how simply bringing the mike in close (if it's omni) in any room can be in anyway comparable to a measurement done in an anechoic environment. the false rationalization that moving the mic closer to the source removes the effects of room acoustics is simply wrong.
close mic'ing and gating can reduce the effects of bad room acoustics but it cannot entirely remove it, if it where otherwise sound and film studios could save themselves a bundle on architectural acoustic treatment.
even outdoor measurements whether they be ground plane or hoisted high for the purpose of removing reflections are still skewed by temperature and air pressure variations that don't exist in an anechoic chamber.
sorry i don't see how simply bringing the mike in close (if it's omni) in any room can be in anyway comparable to a measurement done in an anechoic environment. the false rationalization that moving the mic closer to the source removes the effects of room acoustics is simply wrong.
close mic'ing and gating can reduce the effects of bad room acoustics but it cannot entirely remove it, if it where otherwise sound and film studios could save themselves a bundle on architectural acoustic treatment.
even outdoor measurements whether they be ground plane or hoisted high for the purpose of removing reflections are still skewed by temperature and air pressure variations that don't exist in an anechoic chamber.
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sorry i accidentally deleted that post about RT60
on that note the reason that RT60 is still significant in small rooms (unlike the current standard which is a criterion that is supposed to represent a point at which the decay time affects intelligibility and was established for large venues) is that if we control the decay of all frequencies in the bandwidth of interest to short duration they are no longer able to produce room modes.
on that note the reason that RT60 is still significant in small rooms (unlike the current standard which is a criterion that is supposed to represent a point at which the decay time affects intelligibility and was established for large venues) is that if we control the decay of all frequencies in the bandwidth of interest to short duration they are no longer able to produce room modes.
an example of spectral decay that is the result of a very small enclosure with reflective properties is the typical bathroom.
if we apply RT60 there we would be trying to control mid and high frequencies that just refuse to quit.(this very phenomenon is why some people think their singing sounds better in the shower that reverb creates the illusion of fuller sound, better timbre)
i may catch flak on this but for me spectral decay is a fancy way of saying reverb.
if we apply RT60 there we would be trying to control mid and high frequencies that just refuse to quit.(this very phenomenon is why some people think their singing sounds better in the shower that reverb creates the illusion of fuller sound, better timbre)
i may catch flak on this but for me spectral decay is a fancy way of saying reverb.
There are still quite amount of reflections even with blankets! Perhaps you have not tried.
Basically, the size of the room is of first priority for getting the whole frequency spectrum, then the sound isolation is making sure you get clean measurements. Reducing reflection inside the room is not as important if the size is sufficient.
Blankets still reflect. But if you are able to find a good ration between the walls of the room and the devices, you can probably reduce it to usable levels, but then the shape optimization is also important and you need to float it above the floor.
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Nothing has 100% absorbtion (except a vacuum which really is a case of 0% transmission).
dave
How about something like this? ESP SIM (Sound Impairment Monitor) one input connected to the amp and the other to a microphone, and simply measure the difference, why not?
It will gives a number close to the THD measurements, and perhaps, people will open their eyes and fall from their "perfection" paradigm.
A lot of people seems to think that the perfection in audio is easy to obtain and everyone here is idiot...
Okay here's a link to fr graph for a woofer. If someone can calculate what the decay looks like at 1000 hz I will be astounded.
HiVi M8N-1 Woofer-HiVi
CSD in a room is basically reverb. But with a large enough room and close enough mic you will only see the decay of the driver.
Therfore the rendered measured signal (of music our sounds) should be compared to the electrical signal and then this comparaison will gives a ratio... a ratio of fidelity (if it is what people is looking for).
Never seen this number of my life
That's the theory behind measuring distortion, compare what comes out of the speaker with a signal that is known quantity
Therfore the rendered measured signal (of music our sounds) should be compared to the electrical signal and then this comparaison will gives a ratio... a ratio of fidelity (if it is what people is looking for).
Never seen this number of my life.
measured signal : real complex sinusoidal aperiodic audio signal, not pure tones or computer generated audio artifact noises.
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Don’t like that wriggle in the impedance. Nor the frequency response.
You basically gate the CSD the same way you do in the FR.