Center Channel Frequency Response

Thanks, guys. Makes sense to me to have as full-range a center speaker as funds and space permit. And, Kal, yeah -- ditto for "intelligible."

Lou

I thought "taylored" was more egregious. I do not understand anyone posting without an active spell-checker.

Kal

That quote was from me. OK, OK, so I don't always spell correctly. I'm sure you guys never make a mistake.

You guys really need to do some research about reproducing speech for best intelligibility. Much research has been done on this subject, particularly in context of hearing impairment and high noise environments. Note that I referred to dialogue in movies, not singing.

Here is a sample quote from one paper...

"High-quality speech systems need to cover the frequency range of about 80 Hz (for especially deep male voices) to about 10 kHz (for best reproduction of consonants, which are crucial to intelligibility). Response below 80 Hz must be eliminated to the extent possible: not only do these frequencies fall below the range of the speech signal, but also they will cause particularly destructive masking at high sound levels."

"High-quality speech systems need to cover the frequency range of about 80 Hz (for especially deep male voices) to about 10 kHz (for best reproduction of consonants, which are crucial to intelligibility). Response below 80 Hz must be eliminated to the extent possible: not only do these frequencies fall below the range of the speech signal, but also they will cause particularly destructive masking at high sound levels."

So, 80 to 10kHz is necessary, OK. However, eliminating response outside that range is either irrelevant (if there is no signal content outside the range) or a big mistake resulting in loss of program material (if there is signal content outside the range). So, if it is the latter, one may achieve some advantage in voice intelligibility but at the cost of loss of other content. IMHO, a bad trade-off.

Kal

Actually, the idea of a limited HF frequency range does have some merit specifically for movie soundtracks . . . but it is actually my opinion that VERY few "center-channel" loudspeakers have anything near the required performance anyway, so in most surround-sound systems it can be a moot point.

But the main point is one of "X-Curve" compensation. At some point there was a movie-industry standard established for rolling-off the high end in the sound mixing studio, on the assumption that this emulates the typical commercial cinema acoustic that has lots and lots of HF absorption. I'm not sure if all, or even the majority, of film sound studios use this compensation, but it is a major reason why so many movie soundtracks are REALLY bright. And compensation for the X-curve is the cornerstone of home THX signal-processing (that's where "Re-EQ" comes from).

My theater system is in a controlled acoustic environment, and has had parametric EQ applied for really dead-nuts flat frequency response from all channels. For X-Curve compensation, I've found that a modified approach that applies full compensation in the center-channel, slight compensation in the left and right, and no compensation in the surround channels gives the best results on most movie soundtracks, but for the REALLY bright movies I have a preset for full compensation across all three front, and a slight bit in the surrounds. And for older movies or music surround, I usually like it set to flat response.

From this I would infer that in a situation where a center-channel is being used primarily for movie soundtracks without EQ presets or THX signal-processing, it may be indeed be a justifiable approach to modify the center-channel's HF response from what would normally be used for music reproduction.