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Inactive speakers in the room...any effect?

A recent thread degenerated into a discussion about whether an inactive speaker in the listening room affects the sound of active speakers. I should have been more tactful, and called it a "hypothesis" instead of a "myth".

Now, a hypothesis can be proven by analytic means or by experiment. This particular hypothesis, from the analytic approach, is very unlikely to be true. So, we go on to an experiment.

A listening test was described where a group of listeners were unanimous in saying that sound quality was degraded by an inactive speaker. (By the way, I don't understand why, if there were any effect, it would have to be a degradation rather than an improvement).

However, to be acceptable as a proof, the experiment would need to be done as follows:
1. The inactive speaker should be introduced and removed from the room in such a way that the subjects, and the person conducting the experiment, cannot tell if it is in or out.
2. The listening test should be performed a number of times. A dozen might be sufficient. More would be better, but the subjects would get bored and results would be degraded.
3. The subjects should record their observations (Speaker IN/Speaker OUT) in such a manner that they do not know how the others are voting.
4. The results must be tabulated and analyzed in a statistically valid way.

I doubt that the reported experiment was done this way. It apparently convinced the subjects, but does not constitute a proof acceptable to an objective non-participant like me. Lacking a valid experiment, I must rely on the analytic approach, and find the hypothesis untrue.

Another game that would be fun would be to conduct the experiment in the manner that I suspect it was done, where everyone knew when the speaker was in or out, but use a speaker that, unknown to the subjects, has had its cones immobilized with glue and the vent (if any) closed off.
I think I know how that would come out if the subjects were believers. (Or, for that matter, if they were nonbelievers). This exercise would indicate how much confidence should be put in the experiment that was done.

Are we having fun yet?
eldartford
sidssp
1,077 posts
 
Eldartford,
If you have a pair of old speakers with a 10" or larger woofer, put them at the front corners behind the main speakers, make sure they are not connected to any amp, short the speaker terminals with bare wires, and play some bass heavy music like the opening track of the movie soundtrack Titanic or the Ray Brown Trio Soular Energy. Now turn the old speakers around so that the woofers are facing the front wall and listen for the difference. I think you will be amazed.
eldartford OP
4,262 posts
 
Sidssp...Yes I agree that in close proximity to the active speakers they would function much like passive radiators (which, by the way, some people think are a bad idea).

I can't do that particular experiment because the walls behind my three MG1.6 speakers are already occupied by embedded multiple subwoofer drivers that are very much active.

I remain to be convinced that a couple of inactive box speakers at the opposite end of the room would have any audible effect. As for a telephone...

Regarding helmholz resonators...they were used during WW1, connected by tubes to a set of earpieces, to detect approaching aircraft long before they were detectable by other means. Poor man's radar. It worked.
sidssp
1,077 posts
 
Eldartford,
Actually, they don't act like passive radiators, they act like bass traps.
clueless
763 posts
 
Our audio club has had a similar problem but with inactive beer cans. Before we get half through a meeting the empty bottles are acting like little Heimholtz resonators and the cans are just playing their own one note tune.

After copious study we decided to go to the foam cooley cups which have a great damping effect. If things sound a unnaturally bright in your system I suggest you clear the room of inactive aluminum cans or go to an audio-grade cooley cup.

Sincerely
I remain
unsound
7,329 posts
 
Clueless, I can see it now, specially formulated from a rare an exotic rubber tree, cryongenicly treated and mounted on a sandwich of sorborthane, exotic wood, rare stone and kevlar over tip toes, with a remote controlled blue light that can be programmed to glow ones name at the touch of a remote control, cooley cup. Don't forget the sipfrom coasters!
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