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Old 31st December 2007, 06:46 PM   #1
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Default Confused About Speaker Design and Hearing Loss

Being 60+ years old, I have lost hearing above about 12kHz. I have searched this forum on this subject and there are many posts about hearing loss with age, but no apparent conclusions about the effect on speaker design.

The holy grail of audio seems to be flat response to 20kHz or beyond. But if hearing above 16kHz is very limited, do we need to design out to those limits? If I instead target flat response out to 15kHz won't my design task be easier, less costly but with equal sounding results?

Or are there artifacts or harmonics that are within my range of hearing that will be lost as well?

Lindsay
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Old 31st December 2007, 07:31 PM   #2
Kensai is offline Kensai  United States
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Well, I can distinguish a primary tone up to right around 16khz. In my rig, I have a nearly limitless ability to EQ digitally, and I've played with really pumping up the top end to see what effect it has. The highest frequency I can set a shelf boost is 16000 Hz, and generally I don't hear any difference until I've set at least +6dB on that, at which point I start to hear more "air", meaning the sound stage seems to open up a bit and the music gets a bit more realistic. I can't actually distinguish what's going on with my ears, but the music becomes more pleasant. That usually caps out in the +12-18dB range, after which the sound quickly shifts from "better" to strident, glaring and really quite flat (not to mention a serious pain to listen to. The exact amount that works well for me depends on my signal chain and what device I'm listening too. Of course, in my experiments it also works just fine with devices that aren't supposed to be able to handle those frequencies, like my Pioneer B20s that are supposed to cut out around 16kHz, just as well as my Grado SR-80 headphones, so I'm not exactly sure what's going on.

What I'm sensing though, is that you could get along with any of the 8" or larger "full range" drivers we talk about around, and probably get away using them straight, no supertweeter like most folk use. Another point to add is that, unless you are the only one who will ever listen to your designs, it wouldn't hurt to at least pay them a little service, like a $2 piezo crossed really hight

Do you have anything in particular in mind at this juncture?

Kensai
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Old 31st December 2007, 08:52 PM   #3
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Kensai,

Thanks for your response. Your hearing is clearly better than mine. I have boosted the high frequencies using the equalizer on my PC and I can boost the 16kHz control to the maximum and I hear no difference.

I need speakers for the bedroom so they will not be in a large room. I looked at the metronome (72 inches tall with the Audio Nirvana 10 inch speakers) and they will probably not pass the wife acceptance factor. I like good bass response and either need to take that into account in the main speakers or consider adding a sub woofer.

I was thinking of trading high end response for low end response hence my initial question. I do like the idea of a full range speaker as I think it will provide better sound than a two way or three way speaker.

I had looked at the Common Sense Audio Web site and was considering using one of their design plans with the Lowther PM6C. Then if there is insufficient bass I could add a sub woofer.

But I am open to anything. I am good with wood working, but have no experience designing speaker cabinets. I have seen the programs online that will calculate speaker enclosure dimensions, and could go that route if that is the best way to go. But if someone has a proven design then I could avoid any potential mistakes.

Any suggestions are appreciated.

Lindsay
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Old 31st December 2007, 09:46 PM   #4
John L is offline John L  United States
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Default Re: Confused About Speaker Design and Hearing Loss

Quote:
Originally posted by LHMAudio
Being 60+ years old, I have lost hearing above about 12kHz. I have searched this forum on this subject and there are many posts about hearing loss with age, but no apparent conclusions about the effect on speaker design.

The holy grail of audio seems to be flat response to 20kHz or beyond. But if hearing above 16kHz is very limited, do we need to design out to those limits? If I instead target flat response out to 15kHz won't my design task be easier, less costly but with equal sounding results?

Or are there artifacts or harmonics that are within my range of hearing that will be lost as well?

Lindsay
Lindsay, I too am an old fart at the young side of sixty, and have what is called bilateral high tone deafness. I am a combat veteran, and got my injury in the military. Too many tank guns and M-16's high pitch crack. Also, I use a compressor in my business, and I wear stereo headphones when I use my staple gun, because the noise of the gun's blade, striking the wood as it drives the staples into the wood, bothers me.

But just because you have a hearing disability does not mean that you are unable to pick up high frequency signals. Inside the inner ear, and also within the cochlea, are tiny hairs, called celia, which act as tuning forks for the different pitch of all sorts of frequencies. Every frequency has celia of certain length and thickness, which generate different frequencies. These frequencies are, in turn, amplified as they move up the auditory nerve to the brain.

As you experience age, or trauma due to loud noise, the celia of certain frequencies are damaged. Over time, they will shrivel up and die. Many, however, will not.That is why a hearing aid will be able to amplify a certain frequency, and you will still be able to hear it. And that is because some of those dedicated celia for that frequency are still functioning. If they were all dead, you would not be able to hear ANY frequency, even with amplification.

Today's digital hearing aids are becoming very sophisticated, in that the number of dedicated frequencies to amplify are increased. Today it is common to see digital hearing aids that have over fifteen or twenty different frequency stages. In a few years, it will be almost unlimited. Perhaps the future ones will be able to amplify sounds every ten cycles, who knows.

But the neat thing is that science is now hot on the trail to manipulating genes in certain animals and regrowing these celia. In other words, by regrowing a full crop of celia, you would be able to hear like you could as a child. And it may be possible to even tailor the celia to grow and pick up frequencies below or over what humans can naturally pick up. Amazing!

I am now at the point where I really should have hearing aids put in my ears. Fortunately the VA will provide them for me, and better yet, give me all the batteries I need, for the rest of my life.

As for hearing, you can still discern certain frequencies that you may not think you should. And with practice you can discriminate more than you could without practice. for instance I can definately tell differences with many of my receivers. My Marantz is about as mellow as you can believe. Yet my Bogen tube receiver, which I am using right now, has a most sublime sound, yet is is as clear as a bell, more so than my Sansui 2000X that I also use with my computer.

So while you may be a little bit challenged, you are not without ability. The best thing to do is shoot for the best, listen carefully, and enjoy the best quality you can provide. I would still try to create a set of loudspeakers that cover the entire spectrum, because chances are you can still hear some of it, and with hearing aids, the possibilities are even better. That's what I would do.
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Old 31st December 2007, 09:55 PM   #5
ronc is offline ronc  United States
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I wish everyone would speak up, i cant hear yall.

ron
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Old 31st December 2007, 10:01 PM   #6
Bobken is offline Bobken  United Kingdom
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Hi LMH,

I am in the same age-group as yourself, and have played around with speakers and X'overs for nearly 50 yrs., but my experiences and advice virtually mirror those of Kensai.

Regrettably, I cannot hear pure sine-waves in excess of 10K-ish now when on test, but disconnecting Townshend Super-tweeters from my system which don't give anything much by way of an output below 20K Hz, gives an immediate 'loss' to me when listening to my audio system.

Amongst other effects, there is a loss of focus of sounds which I miss, so 'don't do yourself down' here, even though you might not think that this matters with your age-related deficiencies.

Regards,
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Old 31st December 2007, 10:06 PM   #7
ronc is offline ronc  United States
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but disconnecting Townshend Super-tweeters from my system which don't give anything much by way of an output below 20K Hz, gives an immediate 'loss' to me when listening to my audio system

True here too. When i added the ribbon tweets to the 208 there was an immediate increase in resolution and a bit of high frequency response beyond my normal 12 Khz limit.

Happy New Year to all authorized personnel.

ron
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Old 2nd January 2008, 01:07 AM   #8
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John L

Thanks for the detailed reply. I was not aware that hearing aids amplified only certain frequencies. What is the highest frequency they amplify? I would be surprised if it were over 10kHz. I live in Arizona and there is a lot of bioengineering activity here. Growing new celia is very appealing. I just hope I live long enough to see it!

Bob, Ron,

I did a little looking on the Web for the Townshend Super-tweeters. It's hard to believe you can hear a difference with them. But if you were willing to shell out $1,600 for them then they must contribute to the sound of your systems. I have often wondered about reproducing square waves with a speaker system. In effect the square wave has a dv/dt that is infinite and would require the highest frequency response possible to properly reproduce, so I suppose it is possible to hear the difference.

In any case thanks for straightening me out of this topic.

Lindsay
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Old 2nd January 2008, 01:18 AM   #9
John L is offline John L  United States
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Quote:
Originally posted by LHMAudio
[B]John L

Thanks for the detailed reply. I was not aware that hearing aids amplified only certain frequencies. What is the highest frequency they amplify? I would be surprised if it were over 10kHz. I live in Arizona and there is a lot of bioengineering activity here. Growing new celia is very appealing. I just hope I live long enough to see it!
I am not personally intimate with digital hearing aids, since I have not gotten to the point where I am in the process of obtaining them. I always make a habit of researching things before I get ready to do something like that.

However, I would guess that the digital aids are programable to work at just about any frequency they choose. The shortcoming is based on the number of frequencies the integrated circuit is set up to handle. Obviously the more channels it can work with, the more expensive. I would suspect that in a few years, you will be able to get a hearing aid that can amplify fifty to one hundred different frequencies, at a reasonable price.

Let's not forget Moore's Law.
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Old 2nd January 2008, 10:52 AM   #10
Bobken is offline Bobken  United Kingdom
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Hi Lindsay,

To set the record straight, I didn't pay for these Townshend Super-Tweeters, as I did some work for someone in the audio trade and this was part of the deal on offer.

However, I had listened to these S-Ts before agreeing the deal and would certainly consider their purchase if I didn't already have these S-Ts, as their effect is worthwhile in my opinion. I did not have them to listen to when my HF 'threshold' was much higher, but my wife's upper limit is a lot higher than mine is now, and she appreciates the improvements/differences similarly

Interestingly, the 'ordinary' tweeters in my system, and which these S-Ts are used together with, have a virtually flat response to past 20k Hz, as I have measured them in my listening room. Also, these S-Ts have an amplitude adjustment which ranges from '0' to '8', and I never use settings above '3' or '4', but mostly (as now) they are set merely at '2'. Much above this, they start to 'dominate' the HF and begin to sound less good, but of course my main drivers are relatively low in efficiency, and I am an extremely critical listener with still very high acuity within my existing range.

What surprises me about this, though, is the fact that I can immediately tell these differences even though there is little S-T output below 20k Hz, and on simple sine wave tests, I cannot hear anything much above 10k Hz!

You mention square-waves, and this is interesting as, of course, one needs to have good HF response in the electronic circuits of any system to reproduce such wave-forms well. In the course of speaker and amplifier developments for around 40 yrs., I have tried many different kinds of experiments, with one of them being listening for some weeks with certain drivers disconnected in my 'usual' 3-way systems, and sometimes even listening to 1 driver alone. I find that this helps when identifying some effects (characteristics) peculiar to certain drivers, which although I have the equipment, I have not been able to measure adequately.

These effects are not amplitude-related, which can be readily measured and quantified, but are the results of the kind of construction and materials used in the drivers concerned. When other drivers and their associated X'over components are used in addition, I find that this tends to be a distraction and confuses these issues, and it is harder to achieve what I wish for here.

If ever you try this, you will doubtless find that on disconnecting a tweeter (in my case currently the lower -3dB point being around 4k Hz) this will have a very marked adverse effect on bass sounds like kick-drums, the initial 'strike' of which is at a high frequency although the main body of sound is maybe only at around a few tens of Hz. The entire sounds in the bass regions go 'soggy' or 'very woolly' for want of a more suitable expression!

It is for reasons such as these (and others which I haven't gone into here) that I suggested before that you should not 'do yourself down' merely based on known age-related hearing losses.

Regards,
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