[JRace]

I'd question the accuracy of the headphones used in audiology testing (at least compared to what is used in studio or audiophile systems).

Headphones, and the more commonly used insert earphones, are required by law to be calibrated at least one per year.
They are only required to produce sounds from 125Hz to 10kHz.

If they were not accurate the test would be invalid.

The FM curve is an averaged curve from multiple samples, it varies with output level, and is not the same for you or me. To design a speaker based on FM curves would be like designing a speaker based on an in-room response.

Only good for one room/ears.

[FullRangeMan]

The recording/mastering process requires absolute flat response.  The challenge as expressed by the F-M research is that humans are less sensitive to lower and higher frequencies at low sound pressure levels.  That's what loudness circuits were designed for, but now virtually all audiophiles are "too pure" for that.

I'd question the accuracy of the headphones used in audiology testing (at least compared to what is used in studio or audiophile systems).

Proper bass reproduction at home requires the application of multiple sources (read "swarm" here at AC or Floyd E. Toole's "Sound Reproduction").  This really cannot be argued against because low frequencies behave like waves and can result in +/- 20 dB responses that vary by listening location and frequency.

To season for individual taste you can try EQ for the higher frequencies. 

The real goal of audiophiles is to achieve emotional satisfaction, not perfection.

Interesting post.
The live music is not the absolute reference as some audiophile magazines proclaim to the four winds.

Audiophile satisfaction is a personal taste, each person had a goal sound concept or target.

[dflee]

I have come to the conclusion that we don't want to hear that live or you are there sound. What I am trying to say is that for us to hear the plucking or bowing of a string or the breath while playing brass or woodwind in the live atmosphere unplugged of course we would be seated where the dbs would be quite high. But in the audio world we listen at quite lower db and expect to still hear that delicate decay of an instrument or shimmer of a cymbal. I have played with and been around enough musicians both inside and outside to know that if you are far enough away so that it is low db than you don't get the micro details from that instrument. Yet somehow the industry has found a way to do just that, (try listening to a double bass live in your living room, it is quite an experience) we can listen to our stereos without the decibels of the actual instrument yet hear detail beyond belief.
Amazing, simply amazing!

Don

[stereocilia]

Hi stereocilia.
Interesting, however, can you re-phrase that for me and other members with same or similar low level understanding. I am sure I am not alone.
Sorry, look like my English vocabulary and knowledge is a little limited.I am 66 years old, therefore, my hearing is slowly going on the fritz...

Guy 13

I'll give it a try.  Let's say for the sake of example that my hearing sensitivity threshold at 4 KHz is 60 dB louder than normal.  So, this means that I cannot hear a sound until it is 60 dB louder than I could when I was a teenager; that is, 60 dB is the quietest 4 KHz sound I can detect.  So, in order to detect a sound coming in at 0 dB (which I could when I was young), I have to add 60 dB of gain at 4 KHz.

Here's the problem, though.  Adding 60 dB of gain gives you audibility for that 0 dB sound, but it also makes a 70 dB sound (which is not particularly loud) 130 dB!  130 dB is very very loud.  Hearing loss does not suddenly increase your tolerance to loud sounds, in fact, it might even reduce it.

So, the best we can do is apply something less that 60 dB of gain and add some compression.  How much for music listening?  Great question.  Most of the science of best how to change sound for a given hearing loss is concerned with improved speech intelligibility.   wife is calling... gotta go.

[ricardojoa]

how do you get 0 db?
Even in dead room at night your spl meter wont read 0.

[*Scotty*]

The zero dB hearing threshold figure is questionable at best. A young ear has an apparent self noise equivalent to that of a microphone with an A-weighted noise level of 20dB SPL. The self noise SPL figure would have to be added to
to the measured threshold SPL of the test subject.
Scotty

[stereocilia]

how do you get 0 db?
Even in dead room at night your spl meter wont read 0.

0 dB HL, not SPL.  The HL scale is normalized, so by definition it is average normal hearing threshold.  I think 0 dB HL is actually something like -5 dB SPL.  If you like, take 20 or 25 dB as the lower boundary for normal.

[stereocilia]

The zero dB hearing threshold figure is questionable at best. A young ear has an apparent self noise equivalent to that of a microphone with an A-weighted noise level of 20dB SPL. The self noise SPL figure would have to be added to
to the measured threshold SPL of the test subject.
Scotty

Zero dB HL thresholds and lower for pure tones are measured routinely in people with normal hearing.    Clinical Audiometers will present pure tones down to -10 dB HL.

[ricardojoa]

Alright, i see what your are talking about.
If someone has a 60db difficiency at 4k hz, they might as well ask an acoustic expert to tailor a sound from using room mode/reflection and wall materials to boost that frequency rather then adding that frequency to the signal. That way, there isnt any other frequency louder as it  is not dependent to the signal.

[stereocilia]

Alright, i see what your are talking about.
If someone has a 60db difficiency at 4k hz, they might as well ask an acoustic expert to tailor a sound from using room mode/reflection and wall materials to boost that frequency rather then adding that frequency to the signal. That way, there isnt any other frequency louder as it  is not dependent to the signal.

I don't follow.  What I'm saying is that the best way to model a 60 dB hearing loss is to play noise at 60 dB.  So, the noise floor is 60 dB, and this is not the same as turning down the volume by 60 dB.

So what's the best way to manipulate the signal knowing it's going to be played back to a system with a 60 dB "noise" floor at some frequencies?  I'm not sure.  Do you turn up the bass in your car as low-frequency noise increases?  Should we turn up the highs if we want to listen to music in the shower?  Probably not.  For music, most likely it makes sense to keep the frequency response the same.

[BobRex]

I have come to the conclusion that we don't want to hear that live or you are there sound. What I am trying to say is that for us to hear the plucking or bowing of a string or the breath while playing brass or woodwind in the live atmosphere unplugged of course we would be seated where the dbs would be quite high. But in the audio world we listen at quite lower db and expect to still hear that delicate decay of an instrument or shimmer of a cymbal. I have played with and been around enough musicians both inside and outside to know that if you are far enough away so that it is low db than you don't get the micro details from that instrument. Yet somehow the industry has found a way to do just that, (try listening to a double bass live in your living room, it is quite an experience) we can listen to our stereos without the decibels of the actual instrument yet hear detail beyond belief.
Amazing, simply amazing!

Yet, I have heard the rustling paper, squeaking chair, foot shuffle at concerts, not so much when the orchestra is going full bore, but during solo intrument passages, from a single violin to a woodwind solo.  At such times, the level is definitely piano or less  (I'd say no more than 35-40dB mid-hall)- a level easily accomplished at home.  Live I may not hear the scraping of the bow, but I do hear the fingers on the strings.  But then again, how much of that are we supposed to hear?  What was the composer's intent?

[rollo]

  Yes we all have a different perspective of the sound.  Our systems accurate or colored in some way reflect our memory of live sound. The live sound can vary depending on acoustics of room playing in.
   Some like a small cozy club some like an open air concert. A solo piano concert in Carnegie Hall will sound different in Lincoln Center. Tonality, harmonic structure and timbre should be our goals. Imaging, detail, decay of notes are there yet we rarely hear it in a live venue.
   As Guy13 stated emotional impact is key for us. When I hear a recorded sax I want to hear the mouthpiece and the harmonic of the bell as well. Another illusion i stereo in general. Left, right, center is not what we experience in live sound. it is mono. So trying to create the illusion can at times sound artificial. Twelve foot wide pianos etc. The sound stage presented should have proper height, width and depth equal in size and volume. A full one piece presentation so the brain does not wander and stays in focus. For me personally the top end is the most critical in reproducing that affect.
     Try listening to a trumpet or Sax live in a bright room as opposed to a dull room. The tonality will be different. Since we are not at the recording venue we are not privy to how that sound really sounds.
    At the end of the day our memory of the real deal and the tools we use to achieve that are subjective to the listener. There is no right or wrong.
     
   

[bdp24]

For a person with impaired hearing, if the impairment is frequency dependent, with the same ears hearing both live sound and reproduced, that person doesn't need a speaker tailored to their impairment, at least in so far as frequency response is concerned. If a perfectly accurate frequency response is achieved in a speaker, that speaker will sound the same as the live sound to the impaired listener. If you see what I mean!

[JRace]

The zero dB hearing threshold figure is questionable at best. A young ear has an apparent self noise equivalent to that of a microphone with an A-weighted noise level of 20dB SPL. The self noise SPL figure would have to be added to
to the measured threshold SPL of the test subject.
Scotty

My own ears measure 0dB HL at 500, 2K and 4K in my left ear, and 0dB HL at 250, 500, 1k and 6k in my right ear.
I have also measured -10dB HL reponses in people.

dB is just a relative scale and 0dB HL is no more questionable than 0degrees centigrade.

[stereocilia]

For a person with impaired hearing, if the impairment is frequency dependent, with the same ears hearing both live sound and reproduced, that person doesn't need a speaker tailored to their impairment, at least in so far as frequency response is concerned. If a perfectly accurate frequency response is achieved in a speaker, that speaker will sound the same as the live sound to the impaired listener. If you see what I mean!

Exactly; I agree.  But, for some hearing losses manipulation of the sound may be preferred by a few listeners to gain audibility where it didn't exist before.  It might make somebody happier to hear the triangle or the flute at the wrong volume level for the sake of hearing it at all.  Or, the intelligibility of some random lyrically-driven pop country favorite (if your into that sort of thing) might be improved if the consonants are suddenly as audible as they would be for a listener with normal hearing after jacking up the highs.  I like leaving a little room for subjectivity when hearing loss is chucked into the mix.

[bdp24]

If a speaker was designed to help such a listener hear, say, music better, it's sound could well be intolerable to all others. You want to hazard a guess as to which group of musicians have uniformily damaged hearing? Symphony Orchestra members! Those horn sections are extremely loud when you're in the middle of them. I had my hearing tested as part of getting Musician's Earplugs made (where the doc makes a mold of your cochlea). I was only twenty four at the time, and I couldn't hear 15,000Hz---14,000Hz only barely. Glad I didn't wait any longer. In spite of that, I still appreciate Electrostatic Speakers!

[stereocilia]

If a speaker was designed to help such a listener hear, say, music better, it's sound could well be intolerable to all others. You want to hazard a guess as to which group of musicians have uniformily damaged hearing? Symphony Orchestra members! Those horn sections are extremely loud when you're in the middle of them. I had my hearing tested as part of getting Musician's Earplugs made (where the doc makes a mold of your cochlea). I was only twenty four at the time, and I couldn't hear 15,000Hz---14,000Hz only barely. Glad I didn't wait any longer. In spite of that, I still appreciate Electrostatic Speakers!

I wonder how loud the 15 KHz tone was.  Really, I would not sweat not hearing 15 K until it's very loud.  That's a really high frequency, and I've heard arguments that 20 KHz as the upper limit for human hearing is unrealistic.

Most noise-induced hearing loss will cause a notch in your threshold response at 3 KHz to 4 Khz first, and higher frequencies are affected later as the notch deepens.  Also, just to clarify, the ear mold impression would have been for of your ear canal.  The cochlea is part of the inner ear.  Taking a mold of that would deafen and probably kill you.

It's definitely smart to use musician's plugs when it's really loud.

[bdp24]

There ya go agin', flauntin' yer high school edumacation 

[*Scotty*]

Any audiologist conducted hearing test should be incorporating an allowance for the equal-loudness contour phenomena which is a measure of dB SPL, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. This is why stereocilia is unconcerned with how well 15kHz is perceived.
 About 20 years ago I had a sinus infection which impacted the hearing in my right ear. I noticed that the stereo image had shifted into the left loudspeakers location,when I stood with my back to the stereo, the image shifted to the right speaker, UH OH!
 Testing by an audiologist showed that I had a 6 dB deep notch at 250Hz. Hearing levels were back to normal range at 125Hz and 500Hz. In fact both ears tracked one another across the entire tested frequency range and were within normal range and even the 6dB notch was not considered abnormal by the audiologist.
 In fact he couldn't see what I was complaining about, as he saw routinely saw people with ears which did not track one another to a much greater extent than mine and this type and amount of variation in hearing response sensitivity was not at all uncommon. In fact precise tracking from one ear to another across the entire frequency test range was uncommon.
Once again, what was I bitching about, other than the fact that the stereo image had shifted to the left loudspeaker, that is. When I asked why a hearing test did not consist of a wider frequency response range than 125Hz to 8kHz, I was told that it was very difficult to achieve adequate sound isolation for testing below 125Hz. As far as the frequency range above 8Khz. was concerned it didn't impact speech intelligibility which was the primary concern of the audiologist. Music appreciation was a last place consideration in this sort test situation.
Scotty 

[charmerci]

Any audiologist conducted hearing test should be incorporating an allowance for the equal-loudness contour phenomena which is a measure of dB SPL, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. This is why stereocilia is unconcerned with how well 15kHz is perceived.
 About 20 years ago I had a sinus infection which impacted the hearing in my right ear. I noticed that the stereo image had shifted into the left loudspeakers location,when I stood with my back to the stereo, the image shifted to the right speaker, UH OH!
 Testing by an audiologist showed that I had a 6 dB deep notch at 250Hz. Hearing levels were back to normal range at 125Hz and 500Hz. In fact both ears tracked one another across the entire tested frequency range and were within normal range and even the 6dB notch was not considered abnormal by the audiologist.
 In fact he couldn't see what I was complaining about, as he saw routinely saw people with ears which did not track one another to a much greater extent than mine and this type and amount of variation in hearing response sensitivity was not at all uncommon. In fact precise tracking from one ear to another across the entire frequency test range was uncommon.
Once again, what was I bitching about, other than the fact that the stereo image had shifted to the left loudspeaker, that is. When I asked why a hearing test did not consist of a wider frequency response range than 125Hz to 8kHz, I was told that it was very difficult to achieve adequate sound isolation for testing below 125Hz. As far as the frequency range above 8Khz. was concerned it didn't impact speech intelligibility which was the primary concern of the audiologist. Music appreciation was a last place consideration in this sort test situation.
Scotty

Hmmm. This could very well be why so many people like Bose!