Frequency Response

[1audiohack]

Hi Ashly;

Is there a winder stretched out version of the same graph, or is that it?

Don't get impatient with me, sometimes I have a hard time following you. Do you mean is there a easier to view graph? Or are you looking for one with extended bandwidth? In all my books that is the only aspect ratio I have ever seen.

Did you by chance read the page I linked you to? If not I would read it.

Don't let an RTA drive you crazy, it's a useful but very limited tool.

[JBL 4645]

Hi Ashly;


Don't get impatient with me, sometimes I have a hard time following you. Do you mean is there a easier to view graph? Or are you looking for one with extended bandwidth? In all my books that is the only aspect ratio I have ever seen.

Did you by chance read the page I linked you to? If not I would read it.

Don't let an RTA drive you crazy, it's a useful but very limited tool.

I’m grandly getting to grips with its understand. I was using this program for the 10th or 14th time.

Equal loudness contours and audiometry - Hearing test on-line
http://www.phys.unsw.edu.au/jw/hearing.html

Limited by effective yes, otherwise I’d be shooting the dark with the EQ.

I'd back up and read it though. I have other things ping-ponging around, you know (information).


Edit: reading up on it now. http://www.lindos.co.uk/cgi-bin/Flex...IEW=full&id=17

[herki the cat]

Measurements don't tell the whole story.

herki:
Well, scotty, do you know why "Measurements don't tell the whole story?"

Most of the time "measurements are being made on the wrong thing with incorrect test equipment. Serious distortion occurs in speakers due to spurious uncontrolled ringing of diaphragm elements & related components requiring controlled damping.

"the Problem is that most drivers do not reproduce the top octave cleanly without artifacts that are grating to the ear. Flat frequency responce is fine providing there is no distortion."

I have to agree with Dr. Bruce Edgar concerning frequency response measurements.

Still, I do not see anyone talking about measurements with "Tone Burst Technology" which really can expose the most subtle spurious ringing artifacts. General Radio Inc produced an excellent Tone Burst Generator 60 years ago which we used extensively in RCA Camden to see defects you could not identify with conventional frequency response or distortion measurements.

[1audiohack]

herki:

Most of the time "measurements are being made on the wrong thing with incorrect test equipment.

Still, I do not see anyone talking about measurements with "Tone Burst Technology" which really can expose the most subtle spurious ringing artifacts. General Radio Inc produced an excellent Tone Burst Generator 60 years ago which we used extensively in RCA Camden to see defects you could not identify with conventional frequency response or distortion measurements.

It has been said "We measure what we know how to measure, because we know how." Also, "That in order to properly measure something you must know everything there is to know about it." I thought well, if you know all there is to know about something, you would not need to measure it right? It sounded silly to me until I really thought about it. So I could to some extent agree to your statement.

Would you mind elaborating on the "Tone Burst" test process a bit? How did the generator work? How did you colllect, view and interpret the data?

Thank you,
Barry.

[herki the cat]

if it sounds too bright”what is the frequency that will have us grumbling and moaning.it’s within (2 KHz to 4 or 5 KHz) what are the tones that normal hearing can percieve ?... 1 2 3 4 5 6 7 8 9 (10 11 12 13 14 15 16 KHz ? tones that sound higher in level than smaller tones because 4 or 8 KHz blocks what is ahead like 10 KHz or maybe 16 KHz. Would it be easier for total flat response in the high range to iron out all the peaks so its virtually flat and easier to hear the common tones with less harshness and .

Not at all, it dose not works like that...but it goes like this:

1) Each of your ear cannels is aprox' one or two centimeters long formining a resonant cavity like an organ pipe in church which yields a 15 db increase in hearng sensitivity around 1500 to 2000 Hz in a narrow band which can be extremely loud for any person with hearing impairment because the natural
hearing AGC, aka "automatic volume control" of a young person no longer functions if you have any hearing nerve damage. Sounds from clanking china in the kitchen & loud speaking persons near you can be devastating and so on into the HI FI Mess.

2)...If you have any hearing imparement due to exposure to very loud sounds like gun fire, excessive rock & roll music, loud HI FI, illness history you may have hearing nerve damage known as "Presbycusis" which will pesent loss of hearing the higher frequencies above 1000 Hz progressively worse with ascending scale of higher frequencies. This can happen at any age; you need not be 75 years old to experience this tragic situation.

3)...With this you will experience "masking influence" by low frequency noises like street traffic or trucks, motor cycles etc, and especially loud speaking females at your side, that seem to drown out your hearing ability . Listening to a speaking person in a small room with hard plaster walls or a kicthen tiled floor that rings like hell in the voice fundamentals spectrum around 200 to 300 Hz will present extremely poor inteligibilty.
4)..Presbycusis is gradual hearing loss in both ears that commonly occurs as people age. Nearly half of all people at any age exposed to loud sounds. Older people naturally have this form of gradual hearing loss which can be mild, moderate, or severe. Presbycusis usually involves permanent hearing loss sometimes referred to as nerve deafness. Certain medical problems can also lead to hearing loss. If you suspect you have presbycusis, contact your doctor.
The Ear
Copyright © 2005 Nucleus Communications, Inc. All rights reserved.

please explore this link www.nucleusinc.com

There are several causes of presbycusis including:

• Gradual degeneration of the eardrum or delicate structures within the inner ear (hair cells) due to age
• Changes in the hearing nerve pathways in the ear leading to the brain
• Repeated exposure to loud sounds, music, or equipment which can damage the fragile hair cells within the inner ear involved in hearing
• Hereditary or genetic influences

Risk Factors: You can explore this subject further in the Wikipedia free dictionary under "presbycusis"

[JBL 4645]

herki

Yes I see what you mean by cavity. If hum the sound is less. If I hum again and place my fingers over my ears the humming is louder because its being produced in-head or cavity, no?

If I may an Arhhh sound where my mouth is open the tone is loud without placing my, fingers on my ears. If I place my fingers on my ears the tone is decreased in level.

Weird LOL

It’s hard for me to maintain a smooth whistle blowing sound/tone 1 KHz without it fluttering and its pitch waving up and down…Okay just managed to hold a steady tone and there’s tiny difference with fingers over ears and without.

Higher 2 KHz the tone is decreased with fingers over ears and without its louder!

I just did this out of the blue rather than using sound generated tones coming from a loudspeaker. In the real world these tones would be everywhere there are no headphones to ware the tones are around us.

I might try this again with sound generated sine wave with fingers pressing on the ear.

http://en.wikipedia.org/wiki/Ear

You know what I find distracting its wearing ear plugs while you are walking down the road! You just hear this low TUMP! THUMP! THUMP! Sound of your footsteps! Now that is creepy!

Basically there’s no way to win over loud traffic noise, unless you walk very, very slowly! At normal walking pace it’s THUMP! THUMP! THUMP! Not sure how loud that is if measured with an SPL db or RTA but sounds way over 80db.

The legs act as sound transmission though the body right up the ears or head/cavity. Wow this whole thing now is making my skin crawl.

[herki the cat]

herki......
item #1)Yes I see what you mean by cavity. If i hum the sound is less. If I hum again and place my fingers over my ears the humming is louder because its being produced in-head or cavity, no?
Item #2)You know what I find distracting its wearing ear plugs while you are walking down the road! You just hear this low THUMP! THUMP! THUMP! Sound of your footsteps! Now that is creepy!
Item #3)Basically there’s no way to win over loud traffic noise, unless you walk very, very slowly! At normal walking pace it’s THUMP! THUMP! THUMP! Not sure how loud that is if measured with an SPL db or RTA but sounds way over 80db.

Item #4...The legs act as sound transmission through the body right up the ears or head/cavity. Wow this whole thing now is making my skin crawl.

herki:
Item#1) Yep! The open ear canal normally acts like a Little tiny one note pipe organ resonating like a "church bell's continued ringing sound", adding duration to sounds around 1500 Hz, thereby adding some 15 db of perceived loudness boost in the 1500 Hz spectrum; this is the spectrum area where we hear best, and finger over the ear closing up the cavity magnifies this action severely just like the cavity behind the woofer in a 1947 klipsch horn.

Item#2) Now when closed up by ear plugs the ear canal becomes a high Q sealed cavity like a speaker enclosure at resonance with additional strong hang-over loudness stimulus. Try chewing a cracker or some crunchy celery while wearing ear plugs or finger over the ear. WOW!!

Item#3) You can get kilo-buck expensive hearing aids with electronic noise canceling performance.... or a $29.00 "Phillips inc" very comfortable over the ear high quality sounding head phone set with good electronic noise canceling features ...On Line-sourced... great around traffic noise , police cars, ambulance & fire trucks etc, and good for music.

Item#4) Its all natural ...comes with the territory, but there is no need to suffer any further....Cheers

[herki the cat]

[QUOTE=1audiohack;286990]Would you mind elaborating on the "Tone Burst" test process a bit? How did the generator work? How did you collect, view and interpret the data? Barry.[/QUOTE

herki:
Tone burst technology examines "loud speaker" spurious response, ringing hang-over, which persists after the applied audio energy to the speaker under test has turned off. This test system requires a good professional microphone with excellent transient response free of the defects being explored in the subject "loud speaker under test."

Continuous on-off... eight-sign-wave duration periods of audio signal, swept from 20 Hz to 20,000 Hz, are applied to the speaker under test to observe for any unwanted signal ringing hang-over activity during the signal-off periods which may persist only milli-seconds after the signal turn off event.

Acceptable speaker ringing hang-over performance permits only one tenth of one sign wave period at any frequency from 20 to 20,000 Hz.

The "Tone burst stimulus audio signal comes from a conventional manual slow sweep, sine wave, 20 to 20,000 Hz audio signal generator via a tone burst "on-off" switching signal conditioning system feeding a high quality power amplifier.

[1audiohack]

Hi Herki;

Thats pretty much exactly as I remember the process. I guess if I had thought out my question better I really wonder how the generator worked. If it wasn't capable of switching on and off at the zero volt point of the sinewave it would really be approaching an impulse which by definition is infinite in frequency and occuring in zero time. What I don't know is how you do it without the switching causing it's own transient as that would drive any loudspeaker into nonlinearity.

Please don't think I am trying to trip you up, I really want to know how they accomplished that.

[herki the cat]

Hi Herki; I really wonder how the generator was capable of switching on and off at the zero volt point of the sine wave. What I don't know is how you do it without the switching causing it's own transient that would drive any loudspeaker into non linearity. I am not trying to trip you up, I really want to know how they accomplished that.

herki:
No problem, 1audiohack;287062, I had intended to mention the requirement for precision on-off switching at the Zero axis, but it took a little doing at 3:00 AM to precisely describe the test system text in concise terms to comply with your request.

The General Radio Inc., Tone Burst Generator dose perform the "on -off" switching precisely... stone cold clean, at the Zero Signal cross over point. You can verify this feature looking at the GR Tone Burst Generator output with a 40 Megacycle Scope which does present a perfectly clean on-off function.

This system hardware does not require Rocket Science. This feature is straight forward to accomplish with vacuum tube designs and high voltages to generate plus & minus 300 volts peak to peak audio signals, from which you can derive pretty steep sided square waves cut down to 10 volts peak to peak to perform the switching control function precisely at the zero axis.

Your only problem is to find a Genuine General Radio Inc., Tone Burst Generator or new equivalent. General Radio closed their doors around 1970.

[JBL 4645]

herki:


Item#2) Now when closed up by ear plugs the ear canal becomes a high Q sealed cavity like a speaker enclosure at resonance with additional strong hang-over loudness stimulus. Try chewing a cracker or some crunchy celery while wearing ear plugs or finger over the ear. WOW!!

As for chewing or crunching on crisps or biscuits they tend to make the visual vibrate practically when looking at TV screen the image just vibrates flutters.

[1audiohack]

Hi Herki;

Thanks for taking the time to explain.

I have two measurment systems that will measure several types of distortion by stepping through the frequency range of interest. With one of them if not both I can hear switching transients that I can't see on my scope. I still trust my ears to some extent. I am saving my pennies for a quality digital storage scope, that should help me answer that question and few others.

So did you say the tone burst generator you folks used was a square wave generator?

Thanks again,
Barry.

[herki the cat]

Hi Herki;Thanks for explaining. I have two frequency stepping systems & I can hear switching transients not seen on my scope. am saving for a digital storage scope. So did you say the tone burst generator you folks used was a square wave generator?Thanks again,Barry.

herki
The General Radio Inc., "Tone Burst Generator" does not function as a square wave generator of the test-stimulus signal. It is not a frequency-stepping system & it functions only as a precision "on-off" switching system employed in the signal path of a manual frequency-swept audio generator permitting the the engineer to dewel on speaker performance areas while engineerng speaker design changes.

The General Radio Tone Burst Generator has a precision "phase-locked clock," counting"eight sine-wave periods" of stimulus-test signal "ON" followed by "eight sine-wave periods" of "zero energy stimulus signal-silence" to present engineering observation of speaker over-shoot ringing aberrations .... these rascals constitute over whelming, long duration, loud sounding trash not observed in any other known measuring technology.

The General Radio System uses the "positive-going" leading edge of the square wave ONLY to prepare the switching circuit to precisely execute the clean "switching-off" event in micro seconds at the zero energy cross over point.

After clocking the "eight sine-wave period of "zero energy stimulus-signal silence" the programmed"negative-going square wave leading edge prepares the switching function of the next "stimulus-test signal "ON" event.

This is a very sophisticated machine originally designed by RCA engineering & manufactured by "Long-Extinct" General Radio inc., sadly, not yet equaled by any popular devices offered by the current industry...digital technology not with-standing.

BTW, This General Radio "Tone Burst Generator" system was the exclusive favorite developement tool of a friendly Camden Rival & Pal, of RCA's Dr. Harry F.Olson, the estimmed RCA Scientist, Dr. Murlan S. Corrinton, inventor of RCA's Microgrove Technology for the 45 RPM 7 inch Disc & the RCA 12 inch Micro Groove LP "45/45" Stereo-Modulation Format, two years before Columbia Records suddenly released the the first production of the the Mono LP Record in the late 1940's, while RCA was preparing the funds for LP Production. (See: Wikipedia "Colombia LP Records" for the story)

[1audiohack]

That's exactly what I was after.

Thank you kindly,
Barry.