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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
unsound
7,329 posts
 
Eldartford, perhaps I was not clear in my original response, But I am comfortable in suggesting that the first 3 criterion were fullfilled ( if not quite a dozen times, quite close, further more some the listeners had the opportunity to do this on more than one occassion spanning a couple of days). As for the statistical tabulation and analysis, I think the unanimous response satisfies that criterion. Do I think that a unanimous response will always be typical, heck no. I do think most people can discern the difference.
wellfed's avatar
wellfed
690 posts
 
Tom, did you ever try putting a pair of inactive speakers in the lower corners of the front wall behind the active speakers?
twl
3,251 posts
 
Wellfed, no I have not tried that, although I have heard of the practice being used for tailoring the room for bass response. However more than just the bass is being re-radiated. I'd prefer to use a more specifically designed item for that purpose.
newbee
4,767 posts
 
I think the original thought on the existence of other speakers in the listenroom had less to do with whether or not you could hear the disconnected speaker, but how their presence could alter the sound of the main speakers. The concept was that without other speakers present the sound could only be attributable to the speakers being demo'd. The falacy with this was that the room itself was a major contributor to the sound as was everything else in it. You still wouldn't know how the speakers would really sound 'til you got them home in your room. This was for me just another audio salon gimmick to add credibility to their image. However, regarding testing, I think it is clear that anything introduced into a listening room will alter its sound. If you disagree, just imagine bringing in plain boxes into the room, one at a time, and thereby changing the volume of and reverberation patterns with each box introduced, until the room was full of boxes. Ditto books, plants, vases, etc. When you add speakers you also introduce things which can vibrate and this will further alter the sound. The only remaining question is at what point does the change in the sound become audible? I think the answer to that question is that it will depend on the quality of the listener's hearing and their knowledge of the acoustics of the listening room and its equipment. I've always thought it humerous to read about listening tests, blind or otherwise, done by panels in rooms where the listeners were seated in various positions, as opposed to having one listening position and letting each listener have the sweet seat (after they have accoustomed themselves to the sound of the equipment and the room. In my experience if you are not perfectly positioned any really subtle changes in sound will be lost. And if you can hear differences when you are substantially off axis there are not subtle ones theat needed to be tested to be proved. Anyway, thats my view.
eldartford OP
4,262 posts
 
Believers...What you are saying is that a "room treatment" device having only about 1/2 square foot of active area has a significant effect. If this is so, why don't the room treatment merchants design a box with a passive radiator (or an active device) to accomplish their purpose without acres of foam on the walls.

By the way two things I can accept.
1. An inactive speaker placed immediately adjacent to the active speaker will function as a passive radiator, and will have some impact.
2. A small audio shop listening room with the walls lined with dozens of speakers would sound different if they were all removed.

A telephone! Now I know you are spoofing me.
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