Is a flat frequency response graph physically possible in headphones?
Aug 3, 2010 at 4:16 AM Thread Starter Post #1 of 11

Lorfa

New Head-Fier
Joined
Aug 2, 2010
Posts
15
Likes
0
A few questions: 
 
1. Would the sound of such a headphone be desirable?
 
2. Do frequency response graphs exist for headphones such as the HE90s and Stax 007s?
 
3. Can speakers come closer to this?
 
Aug 3, 2010 at 3:34 PM Post #2 of 11

edstrelow

Headphoneus Supremus
Joined
Sep 7, 2002
Posts
3,128
Likes
195


Quote:
A few questions: 
 
1. Would the sound of such a headphone be desirable?
 
2. Do frequency response graphs exist for headphones such as the HE90s and Stax 007s?
 
3. Can speakers come closer to this?
 
 
 
 
 
1. Probably not, since it would not actually sound flat.
 
You have to start by asking how do you intend to measure flattness, i.e. where do you put your mike. The frequencies coming into the ear,  increase in  volume between about 2 and 4 kHz due to things like resonance in the ear canal.   So if your phone measured flat using a  small probe mic at the base of the ear canal your are ok, you do have a flat response.  Measured anywhere else or by any other means, no.
 
2.  Probably, but note the reservations in 1. above.
 
3.  I am not sure that speakers can in principle be given a flatter response than phones, considering that they are subject to room resonance effects, that in smaller rooms can be quite whopping.  Generally these are in the lower frequencies and give some pretty nasty bass effects if the speaker previously tested flat in  a large room. 
 
I use an equalizer and mic set-up with my main speakers and the flatter I  can get the speakers to perform the clearer the sound gets.  However you may need to reduce the high frequencies  (in fact my old dBx equalizer has a dedicated roll-off button for this purpose)  because flat  sound is too bright.  This is probably the result of 2 factors related to high frequency attenuation in air.  First the microphones used in the recordings are very close to the source,  closer than a listener would normally be, thus making the sound too bright.  Secondly your speakers or phones are very close to your ears similarly increasing brightness. 
 
Then a lot of rock/pop  seems to have a high frequencey emphasis, probably added in recording making them bright. 
 



 
Aug 3, 2010 at 3:37 PM Post #3 of 11

revolink24

Headphoneus Supremus
Joined
Jan 12, 2008
Posts
2,881
Likes
41
Etymotics are pretty flat straight down to 10 Hz. That sound, to me, doesn't feel "natural" or right.
 
Aug 3, 2010 at 3:50 PM Post #4 of 11

palindrom

New Head-Fier
Joined
Jul 30, 2010
Posts
25
Likes
12
- Everything is possible
- Ideally flat response is impossible
... Wait, what?
smile.gif

 
My point is, yes, it certainly is possible to make headphones with flat response across the auditable range (within some reasonable tolerance range, say 5dB). Our hearing is very non-linear, with maximum near 1kHz. Overall response is personal issue. I don't think that ultra flat response is a real need, current references are flat enough. Anyway our ears, like eyes, have built in signal balancing.
 
You can do it if You want, just use good equalizer, JIG and reference microphone.
 
2) I don't know
3) I think that better question would be, can You make studio with appropriate acoustics?
 
Aug 3, 2010 at 4:55 PM Post #5 of 11

recstar24

Can Jam '10 Organizer
Joined
Jan 9, 2005
Posts
3,410
Likes
14
I believe according to the headroom measurements that Tyll completed, the most flat looking measured headphones were the eytmotic er4s and the sennheiser he90.  However, both of those don;t necessarily sound right to me. the etymotic sounds tilted towards the top end and the he90 is very romantic and lush with a bit of a sheen on top.  Go figure.  All I can say is there are tons of filtering things that your ear does which impacts the way we hear things from how they are measured.  Factor in that we have this crazy DSP in between our ears that seems to do its own thing which is hard to measure.
 
Aug 3, 2010 at 6:12 PM Post #6 of 11

Uncle Erik

Uncle Exotic
Joined
Mar 18, 2006
Posts
22,597
Likes
501


Quote:
A few questions: 
 
1. Would the sound of such a headphone be desirable?
 
2. Do frequency response graphs exist for headphones such as the HE90s and Stax 007s?
 
3. Can speakers come closer to this?

 
1.  Maybe not.  The shape of your ear and inner ear all add their own signature when it comes to what you hear.  It's as individual as a fingerprint, so everyone has a different response to headphones.  Ear shape aside, we all have different experiences and expectations from what we listen to.  A professor at Stanford tests his students on sound preference every year and has discovered that, increasingly, students prefer the hotter sound of a MP3 to live events and high-quality recordings.  The same thing happens, I believe, with overemphasized bass.  Since almost every audio system (and don't think we're immune here) exaggerates the bass, people have come to expect that sound.  However, if you go see a jazz trio at a club you aren't going to get "impact" from the standing bass, though you will hear the notes go all the way down.  Some headphones, like the HD-800, capture the low notes without impact, like the live event.  But a lot of people seem to think that's "bass light" when they don't get a thump, even if the thump isn't there in a live performance.
 
2.  Yes, there are lots of frequency graphs.  Mostly at HeadRoom and I think Tyll has tested quite a few more on his own.
 
3.  Yes, some speakers are very flat.  Some years back, I built a pair of ribbons that were virtually flat above 350Hz.  They roll off hard in the low end, but things like female vocals are astonishing.  If you added a woofer to those and carefully integrated it with a crossover, you could get them rather flat.  A lot of the other planars are good at this - electrostats, AMTs, ribbons, and Magnepans.
 
Aug 8, 2010 at 7:05 AM Post #11 of 11

palindrom

New Head-Fier
Joined
Jul 30, 2010
Posts
25
Likes
12
 
I forgot where to find it...
wink_face.gif


 
Note that those are NOT frequency response of ear. This is the whole system, from auricle to the cortex.
We can see clearly, that "flatness" is a function of overall loudness. Anyway even when we build a system corrected for speakers and ears response, the sound will be very unnatural.
A real challenge would be constructing a system that produces natural sound across different volume levels.
More observations can be found here: http://www.customanalogue.com/elsinore/elsinore_16.htm
 

Users who are viewing this thread

Top