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Question about Response frequency

post #1 of 18
5/14/07 at 11:59pm
Thread Starter 
Hello

excuse the question if its plain stupid, i´ve been reading the forums, seeing which headphones are better, informing myself about response frequency of headphones, but i stumbled around a question that i cant figure out,

now, most humans hear betweeen 19-21Khz, some audiophiles can reach 25-27Khz (most testing equipment reaches 25Khz)

now the In ears which are usualy discussed here in the forums as the best, Ultimate ears, Shure, Westone, i was checking the specs, and i was surprised to find that Ultimate ears response frequencies were 40hz to 16khz, and that Shure had 20hz to 18Khz,

i dont get it, how can they provide quality sound if the spectrum is incomplete ?

once again, i apologize if the question is too "noob" or if i just misunderstood the specifications,

thank you very much in advance,
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post #2 of 18
5/15/07 at 12:26am
There is a cost to designing phones that can handle those higher up frequencies. If music does not actually contain those frequencies than there is little purpose to the phone developer to design a product that holds up until reaching them. Fact is, most music concentrates on the sounds that are easier on the ears, so the higher frequencies aren't needed. Go to http://www.freemosquitoringtones.org/ and play the higher tones. Now imagine music full of it. It would be extremely painful and there would be no market for it. Then there's the cost of making a speaker that can handle that note and fit inside the small body of an IEM and it just plain ain't worth it.
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post #3 of 18
5/15/07 at 12:33am
Thread Starter 
ok, thanks for the response, did some tests, and i can hear the speakers responding but i cant hear 18k and higher, not sure if its a speaker issue or im getting old,

but i did get a headache,
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post #4 of 18
5/15/07 at 1:29am
Plenty of full-size headphones are rated as having a response from 5hz to 35hz. DT-880 Studio and DT-990 for example, at least that I personally own.

But here's the thing: All these specs are fudged. Everybody lies, even if only a little bit.

The actual measured response curve is what we really want to know about. This is why headroom.com goes ahead and measures it.

Although the 80's version 880 and the 90's version 990 both have the same rated frequency response, the 880 Studio (which bears no resemblance to the current DT-880) is much more sensitive above 15khz than the 990. I can hear it, and so could lots of people in the 80's when the 880 Studio was new. Unfortunately, since frequency response above 15khz was typically quite poor in 1984, a lot of otherwise good sources had plenty of hiss and distortion up there, and this earned the DT-880 Studio a mixed reputation - you had to have world-class equipment to really enjoy them. In my experience, the utterly failed followup to the K340 - the K145 - has the exact same problem. Which isn't a problem on modern gear.
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post #5 of 18
5/15/07 at 1:53am
The highest Response Frequency would go to:
"Welcome to HeadFi, sorry about your wallet!"
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post #6 of 18
5/15/07 at 7:54am
I noticed that the measured frequency responses of headphones by Headroom Corp. are EXTREMELY irregular. The Sennheiser 650's have a slight downward slope above 4khz, and fairly deep valleys at 5khz and 18khz, the AKG K701 has a big hump between 6khz and 8khz, and a deep dip a 12khz. The Beyer 880's and 990's don't have any big dips at all, but they have large peaks at 6khz to 10khz-12 khz, and a peak at 20khz. The Grados have a series of huge peaks around 2khz, 5kz, 8khz-10khz, and a recessed treble after that.
What do you guys think a headphone that Headroom Corp. measured as almost perfectly flat would actually sound like?
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post #7 of 18
5/15/07 at 8:04am
my dogs bark when they heard the 21 Khz ,
i can hear 21khz but not 22.357khz , may be my speakers or my ear....
...oh i got headache...
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post #8 of 18
5/15/07 at 8:12am
The reason that the IEM's such as Shure and Ultimate ears only go to ~16Khz is due to a limitation in the technology used. The IEMs your refering to use balanced armature drivers, which have a limitation on frequency response. I'm not sure what the technical reason behind this is, but i'm sure there will be a thread that already exists that can explain this.
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post #9 of 18
5/15/07 at 8:24am
Fortunately for us, in the real world there's not a whole lot of information in music above around 8kHz. Organs and synthesizers can produce fundamentals around 10kHz, but other instruments only put out harmonics up there, and their amplitude rapidly falls off. Yes, the harmonics are important to the full musical experience, but if you don't hear them (either due to age reducing your own response, or to the equipment you're listening to not reproducing them) you'll still get the main part.

As for Headroom and flat frequency response, look at the curve for the Etymotic ER-4S. It's quite flat. I own a pair of these, and they do sound good... under ideal conditions (perfect seal in my ears, no movement to cause cable noise, little ambient noise). In the real world they don't work for me; the Shure E500's somewhat bass-heavy response curve works better for me, at the volume level I prefer. The printed response curve for these looks high-frequency shy, but to my ears they have plenty of listenable detail up high.
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post #10 of 18
5/15/07 at 8:41am
What concerns me is the not the fact that dips and peaks above 10khz should not be that audible, but peaks and dips from 2khz to 8khz would be.
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post #11 of 18
5/15/07 at 10:48am
If I'm not mistaken, I don't believe there's a musical instrument that produces highs anywhere near the 20khz range. Most folks' hearing (once again an assumption) come nowhere near that high. I've read that it's possible that harmonics of certain tones might come closer to the 20khz range, but that's about it.

The 20hz to 20khz frequency range is typically at the outermost frequencies of human hearing, meaning given 100 people a few will be able to hear it, but not many.

So...I wouldn't put too much emphasis on that alone. It's how the headphones (or IEM's) sound to your ears and hearing that's important.

Good luck.

Ciao,
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post #12 of 18
5/15/07 at 11:00am
There are two factors. The first being the limitations inherent in designing a single driver that is responsible for reproducing the entire audible frequency range. This is not easy. The second is that frequency response is not as objective as you might think. It is very much influenced by the acoustics of the space in which it is measured. As loudspeaker focused audiophiles know well, placement and room treatment are almost as important as the speaker itself. The same is true for headphones but on a much smaller scale. For headphones, the acoustic space is all the room in between the driver and your ear drum. This includes your ear lobe, your inner ear, the shape and materials of the headphone cup and pads and even the space surrounding the driver itself. The neutrality of the frequency response we perceive is based on the interaction of all those factors, and it will be slightly different for everyone. As a result, even if it were possible, a headphone designer could not simply draw a straight line across the audible range and call it quits.
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post #13 of 18
5/15/07 at 11:07am
Quote:
Originally Posted by Aevum View Post
now, most humans hear betweeen 19-21Khz, some audiophiles can reach 25-27Khz (most testing equipment reaches 25Khz)
Can you provide a reference for this statement? The range of human hearing is typically stated as ranging from 20Hz to 20kHz. Example. I can't recall ever having seen any study showing that humans can hear to 27khz.
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post #14 of 18
5/15/07 at 11:15am
The other issue with published frequency response curves is that they matter little if they don't indicate what they consider the acceptable step-down value to be. For example, many companies indicate the lower and upper frequency limits based on when frequency response is 10dB down, while others rate by when frequency response is 6dB or 3dB down. As far as accuracy is concerned, I prefer to see frequency respone published with the 3dB down limitations, but very few manufacturers disclose that information.
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post #15 of 18
5/15/07 at 11:21am
Anyone claiming to hear between 25 and 27khz is either full of it or simply using a faulty test. Like if you were using the test tone signal generator in patchmix and calling that a hearing test. After 14 or 16khz the thing starts reproducing an array of overtones below the given frequency. The audible range is given as 20hz to 20khz, but the high end of that range is reduced for most people by the time they are a teenager.

This is a great free hearing test. http://www.digital-recordings.com/
If you use good equipment, read all directions, and are careful in how you set it up (preferably using an spl meter), it can be very accurate. If you can hear the 18 and 20khz tones I will be very impressed and you should do everything in your power to protect that hearing. Again though, this is only valid if you follow all instructions and carefully calibrate your volume level. Use the most neutral headphones and equipment you have.
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