raypenn Posted May 21, 2005 Share Posted May 21, 2005 There have been a number of topics relating to the benefits (or disadvantages) of using equalizers. As I understand it, the purposes of an equalizer are (1) to adjust for issues relating to the quality of the recording, equipment coloring, room conditions, etc., or (2) to adjust sound to meet personal taste. Often, a microphone and RTA are used to make the frequencies flat at a particular point in the room (i.e. the listening chair). It occurred to me that if the frequency response is made perfectly flat, everything has been considered except the actual hearing capacity of the listener. Does anybody know if an individual's hearing can have peaks and troughs over the frequency spectrum, or does an individual's hearing simply have a fall-off at higher frequencies over time? Is is possible to get a hearing test with frequencies plotted out like the frequency response curve of a speaker? I don't really want to do this, but am curious from a theoretical standpoint. Quote Link to comment Share on other sites More sharing options...
Parrot Posted May 21, 2005 Share Posted May 21, 2005 Richard Hardesty wrote some fine stuff on the folly of "room EQ." Check out from page 8 and on, at least, of this journal: http://www.audioperfectionist.com/PDF%20files/journal1rl.pdf Quote Link to comment Share on other sites More sharing options...
Lurch Posted May 21, 2005 Share Posted May 21, 2005 ---------------- On 5/21/2005 7:41:53 PM raypenn wrote: Does anybody know if an individual's hearing can have peaks and troughs over the frequency spectrum, or does an individual's hearing simply have a fall-off at higher frequencies over time? Is is possible to get a hearing test with frequencies plotted out like the frequency response curve of a speaker? ---------------- Yup. When you get a hearing test, it is usually recorded in your records in a chart with a row for each ear and columns for various frequencies. The number in each box is how many decibels BELOW "perfect" hearing your ears are. Thus, you should see 0s across the board for someone who has "perfect" hearing. The bigger the number, the worse your hearing is. You can develop frequencies where you have major troughs due to exposure to high levels of noise at that specific frequency. Jeff Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted May 21, 2005 Share Posted May 21, 2005 Often, a microphone and RTA are used to make the frequencies flat at a particular point in the room (i.e. the listening chair). It occurred to me that if the frequency response is made perfectly flat, everything has been considered except the actual hearing capacity of the listener. Where does one begin? The basic error is that you assign primacy to the frequency domain rather then to the time domain. The results that you are measuring, observing, and hearing in the frequency domain are derivative from phenomena that exist 'fundamentally' in the time domain. Does that make sense? It is simply a different and more revealing view of the elephant. The frequency phenomena you describe are time domain phenomena mapped into the frequency domain. Seen from the point of view of the time domain, the component parts are more readily identified, observed and quantified. Let me try to present a very simple example. If someone shakes a rope tied to a pole 'up and down', from the side you would see the vibration as sine wave. You would also see the waveform reflected back into the rope from the termination at the pole. What results would be a superimposed resultant waveform. This same phenomena, when viewed from above would appear to be a line; a straight line. And the world appears to be a very deceptively simple well behaved place! The point here being that this 90degree transposition of reference is a referred to as a 'transform'. It is the 'same' phenomena, but viewed from a different perspective. It is very similar to what happens when the frequency domain is viewed from the perspective of the time domain. What appears to be relatively simple behavior becomes more apparent in its complexity. And the fundamental components cannot be accurately manipulated from within the frequency domain. They must be addressed from within the time domain. The particular transform that relates the time and frequency domains is the Fourier transform. And it is not the only transform. Unfortunately in math and science, most were taught these functions as simple equations and operations on functions and they were not taught the fundamental underlying relationships. And with the exception of a 'minimum' phase relationship between signals, an EQ does not function as one expects from within the frequency domain perspective. And an RTA looks only at the resultant frequency domain, 'ignorant' of the time domain activity. The tools are too limited for the job. The difficulty with this is that the audio discipline, that has in the past primarily focused upon the frequency domain, has undergone radical fundamental paradigm shift. The recognition and understanding of this change is critical. And this is reflected in here in that some are and some are not familiar with this. And to the degree that this occurs, the two groups are speaking different languages, with only one understanding both languages. Thus ALOT of misunderstandings occur. Just imagine someone trying to explain the complex wave interaction in the rope to one who was only familiar and conversant with their view 'from the top'? They would declare those looking at the event 'from the side' to be nuts! And likewise, those benefiting from the view from the side would have a very difficult time carrying on a meaningful conversation with the 'topsiders' (akin to those who think they can absolve room anomalies with EQ). So it is with those who 'live' in the acoustical frequency domain with regards to those who 'live' in the acoustical time domain. Meaningful dialogue is difficult at best. And understanding is sacrificed. Oh, and we also have groups here who have limited real memory reserves, and this is a such a case where the word count will overflow their limited memory in a sort of buffer overflow, resulting in erratic results. So...be prepared for the erratic results to follow! <?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />Additionally, some are arbiters of the jokes here, relegating others to purveyors of sarcasm in other words a joke that they do not understand or appreciate! If you are interested in further discovering elements in this relationship with the time domain, there are a good number of attachments in the thread: http://forums.klipsch.com/idealbb/view.asp?topicID=63588&sessionID={FFCB43CF-11C3-48B8-B363-FC858789BF1A} Oh, with regards to hearing tests and their correlation to independent acoustical phenomena, there has been an extensive measuring program of the ear's (pinnae) response relative to the phase, intensity, frequency and time responses (etc.) in order to determine an 'optimal' model of the external ear for psycho acoustical measurement. If you are interested in this, let me know and I can dig up some stuff on this. SynAudCon and the researchers at the House Ear Institute have been pursuing this for about 17 years. Quote Link to comment Share on other sites More sharing options...
DrWho Posted May 22, 2005 Share Posted May 22, 2005 ---------------- On 5/21/2005 7:41:53 PM raypenn wrote: It occurred to me that if the frequency response is made perfectly flat, everything has been considered except the actual hearing capacity of the listener. Does anybody know if an individual's hearing can have peaks and troughs over the frequency spectrum, or does an individual's hearing simply have a fall-off at higher frequencies over time? I don't really want to do this, but am curious from a theoretical standpoint. ---------------- I totally understand where you're going with all this, but you've forgotten one important thing: the fact that a person with a "bad ear response" hears the original source with that same "bad response." In other words, let's say this person records a cello sound striving for best tonal accuracy. He is going to make the recording sound as close as possible TO WHAT HE HEARS when he's sitting in front of the cello. To another person with perfect hearing, this recording will sound perfect too because the "bad response" of the first listener essentially gets cancelled out during the process. So if we had a perfect engineer with bad hearing, we should expect that a flat playback response in our systems will allow the engineer's "bad response" to cancel itself out and therefore we should have the same accuracy as if he had good ears...which means we don't need to compensate at all. I know I'm not explaining it well, but hopefull it makes some sense at least. Quote Link to comment Share on other sites More sharing options...
timbley Posted May 22, 2005 Share Posted May 22, 2005 Dr. Who, your explanation makes perfectly good sense to me. My friend has loaned me a book, "Sound System Engineering," which explains the same thing pretty much. You don't want to EQ for people's hearing response because their minds have already compensated for that and it sounds natural to them. If you try to boost frequencies they are deficient in it won't sound good to them. Quote Link to comment Share on other sites More sharing options...
edwinr Posted May 22, 2005 Share Posted May 22, 2005 ---------------- On 5/21/2005 8:53:47 PM dragonfyr wrote: Oh, and we also have groups here who have limited real memory reserves, and this is a such a case where the word count will overflow their limited memory in a sort of buffer overflow, resulting in erratic results. So...be prepared for the erratic results to follow! Additionally, some are arbiters of the jokes here, relegating others to purveyors of sarcasm in other words a joke that they do not understand or appreciate! ---------------- Sorry, I wasn't paying attention. Did you mention my name, dragonfyr? P.S. That was a good post. I understood some of it! Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted May 22, 2005 Share Posted May 22, 2005 Heavens no! I am simply having a bit of fun with ALL the 'flatlanders' out there! The real irony is that this distinction between those persistent to live in the frequency domain are not even aware regarding the issue to which I speak. And I can only imagine how references to it must sound! ...Rather akin to hearing Louis Pasteur mention that their are 'little bugs' in their water and milk, I would think! And while I do not pretend to be Pasteur, I can certainly understand his frustration, where the inability to communicate such a point in 15 words or less renders the messenger as the ignorant one. Ah, but were the world such a simple place! And so many 'blissful' folks! Quote Link to comment Share on other sites More sharing options...
timbley Posted May 22, 2005 Share Posted May 22, 2005 ---------------- On 5/22/2005 2:59:11 AM dragonfyr wrote: Heavens no! I am simply having a bit of fun with ALL the 'flatlanders' out there! ---------------- When you say 'flatlanders', are you referring to the time domain or the frequency domain? Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted May 22, 2005 Share Posted May 22, 2005 Those content to live in the frequency domain, of course! They are easy to recognize! As they run about with their RTAs and EQs! And utter statements such as "But we have ears!" Indeed! Oh, if only the world were so simple! Open your eyes (and ears! and heaven forbid, your minds!)! There is a big exciting world that awaits! --------------------------------- And for those unfamiliar with the term "flatlander" (and no, it is not a term originated by Joe Ely!) Edwin A. Abbott. Flatland: A Romance Of Many Dimensions. Project Gutenberg. (1999, originally published 1884). Devlin, Keith. Mathematics: The Science of Patterns. New York: Scientific American Library, 1994. Tufte, Edward R. The Visual Display of Quantitative Information. Cheshire, CT: Graphics Press, 1983. Quote Link to comment Share on other sites More sharing options...
edwinr Posted May 22, 2005 Share Posted May 22, 2005 ---------------- On 5/22/2005 2:59:11 AM dragonfyr wrote: Heavens no! I am simply having a bit of fun with ALL the 'flatlanders' out there! http://forums.klipsch.com/idealbb/images/smilies/2.gif"> http://forums.klipsch.com/idealbb/images/smilies/9.gif"> ---------------- You can't do that! Have fun I mean. You might hurt someone's feelings... Quote Link to comment Share on other sites More sharing options...
timbley Posted May 22, 2005 Share Posted May 22, 2005 Sorry, I'm time domain deaf. Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted May 22, 2005 Share Posted May 22, 2005 ---------------- On 5/22/2005 3:31:59 AM edwinr wrote: You can't do that! Have fun I mean. You might hurt someone's feelings... ---------------- Indeed! And my silly objection was with issues relating to the fundamental limitations of the frequency domain. Little did I know that the domain of word counts and calendar days form the foundation for the rule of law for too many! I fear there be lots of big toes to step on! Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted May 22, 2005 Share Posted May 22, 2005 Is that Flatland book the one that discusses the possiblity of a fourth dimension by discussion with a being who lives in a two dimensional universe and can't understand the existence of a third? (I'm not making this up, it's a real book, isn't it?) Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted May 22, 2005 Share Posted May 22, 2005 Yes! And that is exactly the same kind of 'radical' paradigm shift that an awareness of the importance and primacy of the time domain introduced into audio. The frequency domain is handy for many things, but one cannot rely on it as a fundamental realm. You can't go home again! But the result is both more complex, and also a more elegant universe! Quote Link to comment Share on other sites More sharing options...
timbley Posted May 22, 2005 Share Posted May 22, 2005 yes, I read that book. It had pictures of these 2D beings, how they ate, fought wars, etc. It's a real brain spinner. I liked how, as a 3D being, there was nothing they could hide from me. I could see right through their bodies, and right down to the core of their planet. Quote Link to comment Share on other sites More sharing options...
timbley Posted May 22, 2005 Share Posted May 22, 2005 So what sorts of things have you been up to in the time domain lately? Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted May 22, 2005 Share Posted May 22, 2005 So what sorts of things have you been up to in the time domain lately? ...Hiding RTAs & EQs (due to their potential for abuse!! The 'pit bulls' of the audio world! - despite my position that they still be available for folks to to be free to make fools of themselves if they wish! Believe it or not, they do have a legitimate, albeit limited, value.), and trying to encourage others to discover the rewards of evaluating their rooms and the interaction of their equipment within the time domain with TEF, TDS and MLS and the many lesser derivative tools available...and making corrections as specifically warranted! Personally I believe in a free people being held accountable for their actions, and not holding the RTA and EQ criminally responsible, but perhaps I should adjust my thinking and consider some sort of 'trigger lock' be required for them until a person demonstrates sufficient acoustical responsibility! Quote Link to comment Share on other sites More sharing options...
timbley Posted May 22, 2005 Share Posted May 22, 2005 Behringer doesn't offer TEF TDS and MLS for under $300.00, so it can't be important. Quote Link to comment Share on other sites More sharing options...
dragonfyr Posted May 22, 2005 Share Posted May 22, 2005 I suspect they rather enjoy selling guns to children too and lurking in adolescent chat rooms! OK, I am having a bit of fun. That's "hyperbole" (no, not the the curve thingie you slept through in algebra!) for those not afraid of a dictionary...ok, ok, too many letters, I know! I should refrain from suggesting anything specific here, but I have a few ideas up my sleeve that will take until at least the fall to begin to come to fruition (Hey, I try to avoid these words, I really do!) that may help folks who are interested.... There are some tools that will allow convolving impulse responses that are beginning to appear. I will try to update all as they become mature enough to recommend, and with a bit of luck (and some help!), we may be able to establish a library of impulse responses ,etc. (hey, that's an insider's pun!) for all to use*.... But don't quote me until I can actually devote the time and energy to do this. *If the full range of applications and the usefulness/significance of this is not readily apparent, please don't worry. But the usefulness ranges from evaluating individual components, to speakers, to both their individual and summed interaction, & ultimately to their use within room modelling programs will make alot of people who 'care' very happy. And there is 'lots happening' in this regards. Quote Link to comment Share on other sites More sharing options...
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