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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: Loudspeaker directivity should be a top priority posted by Duke on July 26, 2015 at 20:23:31:
Another reason why loudspeaker directivity matters is, for the sake of long-term fatigue-free listening.What follows has not, to the best of my knowledge, been the subject of controlled blind testing, so consider this to be just my opinion, unless of course it correlates well with your own experience.
The ear is constantly examining incoming sounds to see if they are new sounds or reflections. When a new sound is detected, the ear/brain system computes its location in space and puts a copy of the sound into a short-term memory (for about 40 milliseconds or so). It then compares subsequent incoming sounds with all the sounds that are stored in this short-term memory. If an incoming sound is the same, then it's a reflection, and its directional cues are suppressed but it still contributes to perceived timbre and loudness. If it's a new sound, then its spatial cues are calculated and a copy goes into this short-term memory. See "Precedence effect" or "Haas effect" in Wikipedia for more information.
Now what the ear/brain system primarily looks at, when deciding whether an incoming sound is a new sound or a reflection, is the SPECTRAL CONTENT of that sound. So, what happens if the spectral content is "close to, but not quite" what the ear would expect after the effects of normal room acoustics? Well, the ear/brain system literally has to work harder to correctly classify this incoming sound. I believe that extra CPU usage causes that part of the brain to become fatigued, and the result is "listening fatigue" or even a head-ache.
Note that at a live, unamplified performance, listening fatigue is virtually never an issue - and the reverberant field is always right. Recall the last time you were aware of listening fatigue, make an educated guess about what was happening off-axis, and see if there's a correlation.
Here's how you make an educated guess about what's happening off-axis: If there is a significant discrepancy between the directivity of the two drivers in the crossover region (like when going from a 6.5" woofer to a 1" dome tweeter), you can expect there to be a major glitch in the off-axis response relative to the on-axis response. And ironically midwoofers that behave pistonically up to the crossover region are more likely to contribute to an off-axis glitch.
An off-axis glitch isn't the only source of listening fatigue, but mentally go back over speakers that you have found fatiguing and see if there isn't a correlation often enough to be of interest.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 07/26/15 07/27/15
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- Another reason - Duke 21:10:12 07/26/15 (0)
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