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  • 2Bdecided
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Are my ears broken?
Reply #25
I've often wondered how much of an impact this has in helping people successfully ABX with headphones.
If the resulting overall frequency response is comparable with what you'd get from speakers (which is the idea) then it shouldn't make any.

What is hugely different is the impulse response (i.e. no reflections vs lots of room reflections), and the interaural separation (i.e. perfect vs only a few dB). I've always assumed this is what makes most of the difference.

More practically, good headphones are arguably available far more cheaply than good speakers - so more people get to hear what's actually in the recording with headphones than speakers.


There are things you can't hear on headphones though. Most obviously, if the recording has transaural processing, and the encoding damaged it, you wouldn't hear this so clearly (or at all) through headphones, as the original undamaged effect wouldn't work properly anyway.

A lot of audiophiles would claim that certain recordings (they consider them to be good recordings) have sound staging that is somewhat like that created by transaural processing - i.e. significant front/back depth, and sound sources that extend beyond the speakers.

Problem with this argument is that even low-ish bitrate mp3 preserves both binaural and transaural signals just fine! In fact it's one of the last properties to be destroyed as the bitrate is lowered - persisting long after transparency and even transient response have been audible compromised.

Cheers,
David.

  • greynol
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Are my ears broken?
Reply #26
Point 1 looks like a TOS 8 violation, but the rest of the OP's post is saying "I can't hear a difference", and the 3-trial ABX was followed by "I can't hear a difference" - so I'm not sure we need to chase ABX results there.

I think you're right David.  That said, I also think it's important that the OP understands how to perform a proper double-blind test.  Still, I probably should have been more gentle, especially because he appears to be opening to learning.


Your eyes cannot hear.

  • chengbin
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Are my ears broken?
Reply #27
2Bdecided

Thank you for your very informative post.

You said that, the flatter the response of your earphones or speakers, the harder it is to tell difference. I have a question. My RE0 is lauded (and criticized) for being extremely neutral. I like this neutral sound. Does neutrality = flat FR?

Point 1 looks like a TOS 8 violation, but the rest of the OP's post is saying "I can't hear a difference", and the 3-trial ABX was followed by "I can't hear a difference" - so I'm not sure we need to chase ABX results there.

I think you're right David.  That said, I also think it's important that the OP understands how to perform a proper double-blind test.  Still, I probably should have been more gentle, especially because he appears to be opening to learning.


No, your response is normal after how I broke TOS #8 the second time. Sorry about that.

  • Martel
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Are my ears broken?
Reply #28
You said that, the flatter the response of your earphones or speakers, the harder it is to tell difference. I have a question. My RE0 is lauded (and criticized) for being extremely neutral. I like this neutral sound. Does neutrality = flat FR?
No, see the previous posts for explanation.
What I understand by neutrality is that properly recorded instruments (like acoustic guitar, drums, trumpet etc.) will sound as close as possible compared to a real world (live) audition. Sadly, this property is usually wasted by over-bassing the headphones (especially in the sub $100 range), treble roll-off etc.
IE4 Rockbox Clip+ AAC@192; HD 668B/HD 518 Xonar DX FB2k FLAC;

Are my ears broken?
Reply #29
Can you recommend some songs that has music with that high of a frequency?


greynol gave you some great links (regarding this and other topics).  I listen to a lot of metal (Bleeding Through, Hatebreed, Dimmu Borgir, etc.) and it contains a bunch of information above 16KHz (mainly the drums).  Most of the songs are still at 16KHz and below but there is plenty of information above that.  Even then, the -Y switch (or an encoder/setting that applies a ~16KHz lowpass filter) doesn't have an audible affect on my music.  That is just me though.

  • greynol
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Are my ears broken?
Reply #30
-Y is not a low pass filter, nor does it even remotely behave like one.
Your eyes cannot hear.

  • aclo
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Are my ears broken?
Reply #31
You said that, the flatter the response of your earphones or speakers, the harder it is to tell difference. I have a question. My RE0 is lauded (and criticized) for being extremely neutral. I like this neutral sound. Does neutrality = flat FR?


Flat FR for speakers and flat FR for headphones do not have the same effect. For example, look at
http://scitation.aip.org/getabs/servlet/Ge...ps&gifs=yes
(I think this is freely available).

To cut a long story short, the experiment is as follows: The subject listens to a signal from two loudspeakers, then through headphones, and matches the loudness. This is repeated for different frequencies (roughly). The result is that one obtains an approximation of how the FR of a set of headphones should be to approximate the flat-FR loudspeaker.  That is, if I play something through a pair of flat-FR loudspeakers, then, if I am now wearing headphones, what must the FR of these headphones be to hear the same thing (in terms of frequencies at least)?

The difference has to do with the way the acoustic waves from the loudspeakers are diffracted, reflected etc by the head, ears and so on, which differs from what happens to signals originating from headphones or earspeakers.

Most headphones are diffuse-field equalized, that is, try to achieve the FR that would be obtained by the experiment above in a reverbant room.

  • singaiya
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Are my ears broken?
Reply #32
Point 1 looks like a TOS 8 violation

True, but it's not such an outrageous claim. I easily ABX'd a random track that was 103 kbps (Nero 1.3.3.0 -q 0.35), so doing it at 110 kbps isn't much of a stretch. And I regularly fail to ABX Lame at ~128 kbps, from the public listening tests I've done.

http://www.hydrogenaudio.org/forums/index....st&p=591802

Quote from: greynol link=msg=0 date=
I've often wondered how much of an impact this has in helping people successfully ABX with headphones.


IIRC, guruboolez used a Beyerdynamic headphone that had exagerrated HF response. It was then speculated that this was a factor to his many positive ABX tests.

Are my ears broken?
Reply #33
-Y is not a low pass filter, nor does it even remotely behave like one.


I am aware of that, I never said that -Y was a lopwass filter.  I simply said that applying the -Y setting or a lowpass at ~16KHz has never affected audio quality for me.

  • chengbin
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Are my ears broken?
Reply #34
Very interesting results.

I did the "mustang" hearing limit test, and my limit is 16kHz. Below 15kHz I can hear clear differences while ABXing. I can't tell a difference between 16kHz and 19kHz. I'm doing this on my earphones, which might have problems reproducing >16kHz. I'll test it with speakers that are -7dB at 20kHz later.

EDIT: Same thing with the speakers. 16kHz is my limit. 15kHz is noticeable.
  • Last Edit: 17 December, 2009, 07:12:05 PM by chengbin

  • chengbin
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Are my ears broken?
Reply #35
Just curious, does a cold affect your hearing?

  • odigg
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Are my ears broken?
Reply #36
Just curious, does a cold affect your hearing?


Yes.  First of all, having clogged ears (even if they are not totally clogged) is quite common when having a cold.  Beyond that, being sick is probably going to diminish your concentration.  You need to be focused during an ABX.

Of course, on a good day (cold free and enough mental space for good concentration) I still can't tell the difference between 192k MP3 and lossless
  • Last Edit: 17 December, 2009, 11:33:56 PM by odigg

  • Martel
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Are my ears broken?
Reply #37
I listen to a lot of metal (Bleeding Through, Hatebreed, Dimmu Borgir
Practically every later Dimmu Borgir album has a lot of content above 16kHz, especially on the Enthrone Darkness Triumphant and Spiritual Black Dimensions albums which have really piercing hi-hat and cymbol sound (quite exaggerated, I can't imagine a real hi-hat sounding like that) .
These are also the albums which I used to bring the lossy encoders (around year 2000) to their knees.
IE4 Rockbox Clip+ AAC@192; HD 668B/HD 518 Xonar DX FB2k FLAC;

  • chengbin
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Are my ears broken?
Reply #38
After lots of ABX testing, I concluded that I'll be sticking to LAME for audio encoding. I'll use V5 setting because audio is transparent at this quality. I saved a lot of space by using this instead of Nero q 0.6.

Thanks everybody. I discovered a lot about my hearing, audio compression, and the "real" bitrate needed for transparency.

Now I wonder the point of the huge lossless tracks on Blu-rays. I think you can get very transparent results with around 1.5Mbps for any equipment source. I wonder if people can hear differences between the TrueHD soundtrack and lossless soundtrack on their Blu-rays.

Another question, the more I read here, the more it says that NeroAAC is better than LAME with low bitrates, like me (128Kbps). Why am I not hearing that? I think at 18Kbps less, NeroAAC should at least be on par with LAME. This time I ABXed it, getting it right every single time.
  • Last Edit: 18 December, 2009, 11:19:22 PM by chengbin

  • Ron Jones
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Are my ears broken?
Reply #39
I wonder if people can hear differences between the TrueHD soundtrack and lossless soundtrack on their Blu-rays.

I often hear claims of people being able to discern "night and day" differences (a phrase which generally causes me to cringe upon hearing it), but I've never seen any ABX tests to substantiate any of these claims. My opinion is that the inclusion of lossless audio on Blu-rays (and HD DVDs, when they were around) is mere marketing, though it's not an entirely bad thing in my opinion. The discs themselves have an incredible amount of storage space, so video quality is rarely sacrificed for the inclusion of lossless audio.

Another question, the more I read here, the more it says that NeroAAC is better than LAME with low bitrates, like me (128Kbps). Why am I not hearing that?

These days, I would call 128 kbps a moderate bitrate. AAC tends to excel at much lower bitrates (particularly HE-AAC), whereas LAME performs admirably in the moderate and high bitrate ranges.

  • chengbin
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Are my ears broken?
Reply #40
Another question, the more I read here, the more it says that NeroAAC is better than LAME with low bitrates, like me (128Kbps). Why am I not hearing that?

These days, I would call 128 kbps a moderate bitrate. AAC tends to excel at much lower bitrates (particularly HE-AAC), whereas LAME performs admirably in the moderate and high bitrate ranges.


I did some low bitrate NeroAAC test (80Kbps). It sounded surprisingly good. It is not until I ABX it until I hear obvious high frequency artifacts. It is like they used some trick to get the high frequencies.

If I didn't hear the source, I think I might be happy with the sound quality. I'm pretty surprised.
  • Last Edit: 19 December, 2009, 08:42:19 AM by chengbin

  • singaiya
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Are my ears broken?
Reply #41
Another question, the more I read here, the more it says that NeroAAC is better than LAME with low bitrates, like me (128Kbps). Why am I not hearing that? I think at 18Kbps less, NeroAAC should at least be on par with LAME. This time I ABXed it, getting it right every single time.


Not all versions are the same. You could always try an earlier version of NeroAAC. That's what I did and I can't ABX the same files/bitrate that I could with 1.3.3.0.. IIRC Nero changed behavior of the lowpass filter in 1.3.3.0 and maybe that's what you (and me) are hearing with it.
  • Last Edit: 19 December, 2009, 05:54:38 PM by singaiya

  • Bodhi
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Reply #42
I've learned alot here.

Thank you!

  • solive
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Reply #43
Now I say that anyone who says you can't hear the difference between lossy and lossless just needs better equipment.

...and what you say about needing better equipment is actually a myth, but whatever.

Do you have any other details to give us to go along with your anecdote (ABX logs, encoder(s) used and what settings, etc.)?

This may be obvious to those who do this regularly, but what double-blind protocol allows one to order multiple files by bitrate exactly?


I think you have to define what "better equipment" means based on meaningful performance specifications and technical measurements. Obviously if the equipment cannot accurately reproduce the entire bandwidth of the audio signals being tested, or it has high levels of distortion (usually the loudspeaker/headphone/room is the culprit here) then that could constitute a bias in the listening experiment.

Even the codec testing standards like ITU-R BS. 1116  have something to say about a minimum performance standard for the equipment and listening room used for conducting tests -- although one could argue they are not well-written.

Cheers
Sean
Audio Musings
Sean Olive
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  • greynol
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Are my ears broken?
Reply #44
Obviously if the equipment cannot accurately reproduce the entire bandwidth of the audio signals being tested, or it has high levels of distortion (usually the loudspeaker/headphone/room is the culprit here) then that could constitute a bias in the listening experiment.

Both cases will usually make the ability to distinguish lossy from lossless easier, not harder.
Your eyes cannot hear.

  • solive
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Reply #45
One exception: Headphones aren't supposed to have a flat frequency response - they're supposed to simulate the frequency response of the part of the system that's missing (i.e. speakers > outer ear) which, due to the shape of the head and outer ear, isn't flat at all. That's OK - that won't break any codec - that just makes them as close as possible to normal listening.

I've often wondered how much of an impact this has in helping people successfully ABX with headphones.


Another problem with headphones - depending on the design - is you get a lot inter-intra listener variance in the frequency response measured in the ear due to how its fits and couples to the individual's ears. If different sounds are being delivered to the listeners at different times, then this could be a source of error variance in the listening test.

The biggest variance is at low frequencies from air leaks, and at high frequencies.  This is certainly a factor when doing listening tests with binaural recordings/room scanning and measuring headphones. There are ways of calibrating for and removing these errors. The worse headphones types in this regard  earbud-type phones that sit in your concha.

Cheers
Sean
Audio Musings
  • Last Edit: 14 March, 2010, 04:20:08 PM by solive
Sean Olive
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Reply #46
Obviously if the equipment cannot accurately reproduce the entire bandwidth of the audio signals being tested, or it has high levels of distortion (usually the loudspeaker/headphone/room is the culprit here) then that could constitute a bias in the listening experiment.

Both cases will usually make the ability to distinguish lossy from lossless easier, not harder.


I don't understand how a poor loudspeaker can make it easier to distinguish lossy codecs from lossless ones.

For example, if the lossy codec applies a low pass at 15 kHz, and the loudspeaker dies at 12 kHz, wouldn't it be more difficult to hear the difference between the two codecs? You can't hear differences between the two signals if the loudspeaker can't reproduce the differences?

Cheers
Sean
Audio Musings
  • Last Edit: 14 March, 2010, 04:15:24 PM by solive
Sean Olive
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  • greynol
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Reply #47
That's easy.  Frequencies not being reproduced between 12k and 15k will no longer provide necessary masking for the lossy encode to sound transparent.

Do I have to dig up the example of the guy with only an 8k response who was more able to distinguish lossless from lossy than the rest of the participants in the test?
Your eyes cannot hear.

  • googlebot
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Are my ears broken?
Reply #48
Lossy codecs make assumptions about masking. For example, a loud 15 kHz tone may mask an immediately following tone (e.g. 1 kHz). Then the following tone is discarded to save space. In a playback chain with relatively flat frequency response this works beautifully and both versions are usually indistinguishable. If a system has a flawed FR and, for example, a severe dip at 15 kHz, the tone that should have masked the 1kHz tone isn't there anymore and so the missing 1 kHz becomes audible in comparison to the original.

That's pretty simplified, but that's about how it works. There are numerous other steps of the process, that ideally expect a playback environment with flat frequency response. Higher bitrates usually leave some headroom, but the basic principle is the same. You can easily verify this by comparing a strongly filtered lossy track against the original with the same filtering applied.

PS Greynol was faster and needed less words...

PPS It also works the other way around. Lossy encoders hide noise below masking components and if those are gone the noise becomes audible.
  • Last Edit: 14 March, 2010, 04:35:26 PM by googlebot

  • solive
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Reply #49
That's easy.  Frequencies not being reproduced between 12k and 15k will no longer provide necessary masking for the lossy encode to sound transparent.

Do I have to dig up the example of the guy with only an 8k response who was more able to distinguish lossless from lossy than the rest of the participants in the test?


OK, I can understand how removing room reflections (via headphones) and part of the audio spectrum in the playback chain could enhance audibility of certain lossy codec artifacts through temporal/simultaneous unmasking. But at the same time, it could make other artifacts less audible as in my example.

So what criteria do you use in defining the performance of a standard playback system for testing codecs?  To my knowledge, the objective measurement of  audio codecs based on perceptual models,  like PEAQ, are based on listening tests where the playback system was reasonably accurate using listeners with normal hearing --  test conditions that you suggest may over-estimate the transparency of the CODEC under less ideal playback conditions.



Cheers
Sean
Audio Musings
  • Last Edit: 14 March, 2010, 05:10:03 PM by solive
Sean Olive
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