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There are many references to the importance of getting the midrange frequencies correct before worrying about high or low frequency extensions. I recall reading somewhere about Bell Labs research in designing the telephone. Believe they identified something like 100-3,200 CPS as the critical range for voice recognition. This covers the fundamentals and first and possibly second overtones of the human voice.
Can anyone verify this frequency range or amplify on the BL research?
Thanx.
Follow Ups:
100-3000 was established by Bell Labs long ago as the frequency range which is needed to transmit a reasonable reproduction of the human voice, not only with regard to intelligibility, but also with regard to recognizing a particular person's voice.Unfortunately, many current phone manufacturers don't care about audio quality, which is why so many phones sound like crap.
(Edit: Of course, those crappy phones wouldn't be on the market if there weren't people who buy them. ;) )
Some bass notes boom = critical (under 30Hz. maybe not that critical)
Treble too bright = critical
Mid-range too forward = critical
Room too lively = critical
Room too dead = critical
Any significant frequency response coloration that distracts you from the music = critical
We audiophiles can be very critical compared with musicians listening to recorded music who try to overlook sound system faults
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Richard BassNut Greene
Born Again Subjective Audiophile 2007
The 'intelligence' band is 300 to 3600 Hz. I don't remember my source of that info, but they were describing the frequency band needed for intelligible speech.
Also, I think 'billw' is onto something regarding crossovers in that area. I recently picked up a pair of Infinity Reference Four speakers, and they literally work wonders on vocals. The midrange drivers do 300 to 4000 Hz, which is perhaps critical.
Best,
CAC
which led, in my thinking, to the original post.Considering the center channel for an AV setup (secondary to my 2-channel audio) which would primarily produce voice, what should be the target frequency range? Drawing from the Bell Labs work, could a single, quality driver capable of 300-3K Hz produce decent voice track information? I'm assuming the full range L/R channels would add the necessary frequencies above and below this range for overall sound balance.
I don't like the idea of most commercial A/V center channels with their horizontal D'Appolito configurations so I'm considering a DIY single driver. Home theater sites will likely promote standard market products so I'm asking here for a more "audio purist" perspective.
Howdy
Well sound you get on the telephone is a direct result of their work :)
If you used a center speaker with a similar freq response, everything would sound like it's coming over a telephone.
Some single diver designs sound quite good for HT as well as normal listening (I have a pair of Cain & Cain Abbys for the secondary system.)
-Ted
The other problem is that there is much more than just voice that comes over the center channel so it would be a mistake to limit it to 300 - 3000 Hz. Besides 300 - 3000 Hz does not accommodate singing.... it is only sufficient for normal speech.
Approximately 300 - 3000 Hz is generally accepted as the frequency range required for voice communication. In fact, many shortwave and HAM radio receivers have bandpass filters that sharply attenuate frequencies outside this range. I have found that the higher frequencies within this range tend to punch through interference and noise better than the lower frequencies - - - I used an Astatic D104 microphone with a crystal element for this reason (over the Shure 444 dynamic microphone) as the D104 favored the higher frequencies and would sound more "crisp".
Of course, we're talking about voice communication if we limit ourselves to 300 - 3000 Hz (or very low fi music!), not high fidelity for good music reproduction.
Hi All
I live in the UK with 230-240v supply. I have a purpose built home cinema/audio room 12'w x 20'l
with 7.1 audio for cinema and 2 channel for cd/reel to reel/turntable all top quality.
The power for the room is a ring main (4 x double sockets) into its own fuse in a distribution unit.
This is a modern brick detached house built 14 years ago and has been thoroughly checked out for mains faults by a qualified electrician using the latest test gear. This part is rock solid!
For the last 2 years my neighbour (HAM Op) and I have tried to sort out why I get blast with morse code as soon as he starts sending if I am watching any DVD/Blu-ray/Satellite etc. He sent his wife in with mobile phone to check output from his rig and the effect on my system - he was blasting me out on all channels so turned them down accordingly - that was the end.........or so I thought. 2 weeks later he was back to outputting at full power and blamed me/my system for the morse reception and refused to help further - I AM A PROFESSIONAL! - put me in my place. Unfortunately there is no body/agency I can turn to accept OFCOM who told me to put 1k capacitors on all speaker leads and goodnight.
I have recently been in touch with Chord Company and they have been extremely helpful with a number of things to try - running cable shields to earth, try looking at earth path etc. It is here I hope I have made a breakthrough:
Cinema Amp/Receiver: Sony str-da2400es
Audio Amp: Musical Fidelity A308
all digital inputs (HDMI 1.4) into Sony
pre amp L/R into Musical Fidelity
both amps have IEC mains sockets, however the Sony does not have an earth pin, just L and N.
The MF has all three, L/N/E
I have tried an earth wire from the casing of the Sony to earth but no effect, morse loud as ever.
Tried switching off the MF to front L and R, still morse. Switched off Sony and MF back on total silence - kind of result I hope. I have tried to Sony Receivers and they both suffer from interference i.e. morse code when sending.
Can anyone help please, really stuck........
Mike Spence
I like all of the responses here. Very useful information guys!
Hi All
I live in the UK with 230-240v supply. I have a purpose built home cinema/audio room 12'w x 20'l
with 7.1 audio for cinema and 2 channel for cd/reel to reel/turntable all top quality.
The power for the room is a ring main (4 x double sockets) into its own fuse in a distribution unit.
This is a modern brick detached house built 14 years ago and has been thoroughly checked out for mains faults by a qualified electrician using the latest test gear. This part is rock solid!
For the last 2 years my neighbour (HAM Op) and I have tried to sort out why I get blast with morse code as soon as he starts sending if I am watching any DVD/Blu-ray/Satellite etc. He sent his wife in with mobile phone to check output from his rig and the effect on my system - he was blasting me out on all channels so turned them down accordingly - that was the end.........or so I thought. 2 weeks later he was back to outputting at full power and blamed me/my system for the morse reception and refused to help further - I AM A PROFESSIONAL! - put me in my place. Unfortunately there is no body/agency I can turn to accept OFCOM who told me to put 1k capacitors on all speaker leads and goodnight.
I have recently been in touch with Chord Company and they have been extremely helpful with a number of things to try - running cable shields to earth, try looking at earth path etc. It is here I hope I have made a breakthrough:
Cinema Amp/Receiver: Sony str-da2400es
Audio Amp: Musical Fidelity A308
all digital inputs (HDMI 1.4) into Sony
pre amp L/R into Musical Fidelity
both amps have IEC mains sockets, however the Sony does not have an earth pin, just L and N.
The MF has all three, L/N/E
I have tried an earth wire from the casing of the Sony to earth but no effect, morse loud as ever.
Tried switching off the MF to front L and R, still morse. Switched off Sony and MF back on total silence - kind of result I hope. I have tried to Sony Receivers and they both suffer from interference i.e. morse code when sending.
Can anyone help please, really stuck........
Mike Spence
Your neighbor is almost certainly correct: the problem is with your gear, not his, if the interference happens, as you say, when you are playing recordings and not doing any radio or TV reception.
You will have to try combinations of different equipment and cables to isolate the component(s) and cable(s) that are reacting to perfectly legitimate RF signals that they should be rejecting because they are not in the audio frequency band.
Switching off a component is just one isolation technique. Connecting and disconnecting wires is more likely to be critical. I suggest you follow a "start small" diagnostic strategy of connecting just the amplifier and speakers and then adding additional wires and components one at a time. Remember, "Every wire is an antenna."
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
..of The Absolute Sound, Harry Pearson, here is the way the frequency range is divided (at least for review purposes in that publication):Extreme bottom.............below 32 Hz
Low bass, bottom octave....20 to 40 Hz
Midbass....................40 to 80 Hz
Upper bass.................80 to 160 Hz
Lower midrange.............160 to 320 HzMidrange...................320 to 2560 Hz
Upper midrange.............2560 to 5120 Hz
Highs. lower highs.........5120 to 10,240 Hz
Extreme highs, top octave..10,240 to 20,000 Hz
In my experience, if a system or maybe we should say loudspeaker, is clean sounding and flat frequency response from 80hz to 14khz, it's going to sound pretty good. I friend of mine who once owned a high end audio saloon, used to say that few people have heard a clean 50hz note. Let alone a system that went from the magical 20 to 20khz. Hifi books from the 1950's talked about getting 100 to 10khz right, then worry about adding what we now call a subwoofer. On the other hand the range of the human voice say 300 to 6K is critical too, if there is a sloppy crossover point in the speaker, the system won't sound right too. This is why single driver speakers have such a following.
Just go to a big box store, look at the specs for some big tower speaker or surround sound sytem that will do T-Rex stomppimg around your living room, and listen to music through it, then find a decent bookshelf speaker and see which one you would want to live with. Hope this helps and made some sense.
Maybe the page linked below will be of interest to you.
æNormal is just a setting on my dryer.
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