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Topic: How important are frequencies over 13 kHz? (Read 23617 times) previous topic - next topic
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How important are frequencies over 13 kHz?

Hello,

I can hear pure tones up to 16500 Hz, but when I listen to music, I can't notice anything over 12500 Hz: if I make a low pass filter at 12.5 kHz or 13 kHz, I can't tell the original audio from the filtered one.

For me, the perceived quality really starts to get worse if the cutoff filter goes below 11 kHz, and it becomes horrible at 8 kHz. But changing the cutoff frequency between 11 kHz and 12.5 kHz, the difference is barely audible. And finally I can't tell the difference if the cutoff reaches 13 kHz (and over).

So I wonder if my ears are not very good (but they are quite good with pure tones, up to 16500 Hz) or if the frequencies above 13 kHz are not really important for most music.

Thanks

ipotesi
Italy

How important are frequencies over 13 kHz?

Reply #1 –
Your situation is very typical. Most people can hear single tones several kilohertz higher than the highest frequency they can hear in music.

(And that makes posting number 1000 for me)

How important are frequencies over 13 kHz?

Reply #2 –
It really depends on the genre and instruments involved. Rock/metal fans are particularly sensitive to lowpassing since it wastes the "metallic" sound. 
Try getting some hi-hat/acoustic guitar recording and lowpass it. 13kHz lowpass should waste the sound alot.

How important are frequencies over 13 kHz?

Reply #3 –
interesting, ive tested my hearing up to 18khz, 18.5 on a good day, but i know i notice low pass filters immediately eg 32khz sampling rate i can effortlessly identify in just about any music

i may do some abx tests later today
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #4 –
btw what kind of music are you listening to there ipotesi?
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #5 –
Quote from: thundat00th on
btw what kind of music are you listening to there ipotesi?


Many kinds, especially 1970's and early 1980's. Almost nothing from the 1980's, and a little bit from the 2000's. Mostly progressive rock, something from regular pop and rock, and even hard rock (not heavy metal, that I consider different) and discomusic (late 1970's). Then, Italian pop, some classical music and operas.

I guess that in the 1970's the frequency response was already up to 16 or 20 kHz, while I think it was worse in the 1960's: possibly, not more than 10 kHz until 1969 (just my guess - I can distinguish sounds from 10 to 12 kHz :-) )

By the way, which typical songs can show the importance of frequencies above 13 kHz?
I tried with Boston (the most "metallic" CD I have), but I found weak signals over that frequency: I can't hear those signals inside the songs, but I can hear them if I make a highpass at 13 kHz: just kind of weak whistles, with the rythm of the song.

Ipotesi

How important are frequencies over 13 kHz?

Reply #6 –
i would say modern recordings with lots o cymbal would at least be the most obvious to hear, i cant say offhand what kind of music would have MORE though

all the frequencies should be there with recordings from the 60s, however they are probably undefined, or just master tape noise

i dont have any Boston (my father may though) but i have some similar music to Boston

here we go http://www.independentrecording.net/irn/re...ain_display.htm
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #7 –
Code: [Select]
foo_abx 1.3.1 report
foobar2000 v0.9.5.5
2008/09/29 19:39:44

File A: G:\Music\Van Halen\Van Halen (1978)\03 - You Really Got Me.flac
File B: C:\Documents and Settings\thundat00th\Desktop\03 - You Really Got Me.flac

19:39:44 : Test started.
19:39:55 : 01/01  50.0%
19:40:02 : 02/02  25.0%
19:40:06 : 03/03  12.5%
19:40:12 : 04/04  6.3%
19:40:15 : 05/05  3.1%
19:40:19 : 06/06  1.6%
19:40:23 : 07/07  0.8%
19:40:40 : 08/08  0.4%
19:40:51 : 09/09  0.2%
19:40:58 : 10/10  0.1%
19:41:28 : 11/11  0.0%
19:41:36 : 12/12  0.0%
19:41:43 : 13/13  0.0%
19:42:01 : 14/14  0.0%
19:42:05 : 15/15  0.0%
19:42:12 : 16/16  0.0%
19:42:13 : Test finished.

 ---------- 
Total: 16/16 (0.0%)

this first one i did i resampled it to 24khz and compared it with the original (i used the HDCD remaster if your curious) with 0 chance of simply guessing
there was no contest between the two

Code: [Select]
foo_abx 1.3.1 report
foobar2000 v0.9.5.5
2008/09/29 19:23:35

File A: G:\Music\Van Halen\Van Halen (1978)\03 - You Really Got Me.flac
File B: C:\Documents and Settings\thundat00th\Desktop\03 - You Really Got Me.flac

19:23:35 : Test started.
19:23:58 : 01/01  50.0%
19:24:33 : 02/02  25.0%
19:24:41 : 03/03  12.5%
19:24:50 : 04/04  6.3%
19:24:57 : 05/05  3.1%
19:25:04 : 06/06  1.6%
19:25:13 : 07/07  0.8%
19:25:24 : 08/08  0.4%
19:25:30 : 09/09  0.2%
19:25:36 : 10/10  0.1%
19:25:43 : 10/11  0.6%
19:25:52 : 11/12  0.3%
19:26:03 : 12/13  0.2%
19:26:09 : 13/14  0.1%
19:26:16 : 14/15  0.0%
19:26:26 : 15/16  0.0%
19:26:28 : Test finished.

 ---------- 
Total: 15/16 (0.0%)

but 24khz only resolves up to 12khz, so i did another resampled at 32khz (cutoff 16khz), and I could still hear a difference

i was also going to do a Velvet Underground song from 1968, i could hear the difference at 32khz, and was going through it fairly quickly, but my sound card (drivers?) crashed halfway through the test, and i figured this was complete enough as is, however the difference was quite subtle, so you may have a point about recordings pre ~1970
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #8 –
You don't say how you resampled. Resampling to 32 kHz doesn't necessarily mean that frequencies all the way up to 16 kHz will be preserved.

How important are frequencies over 13 kHz?

Reply #9 –
The "sssss" of hihats is below 14khz, but any significant reverb will extend above that.

For testing if a cutoff at 13khz is indeed useful, you need to test under the following conditions:

1. Very low noisefloor!

2. Speakers which can *accurately* reproduce 13-16khz and which do not mask those freqs (with exaggerated highs (8-12khz), the freqs above may easily get masked).

3. Music material which has significant reverb

4. Knowing what to hear out for: Stuff above 13khz is almost only reveberation/ambience. There is no "music" and "melody" content at those freqs... what those freqs carry is almost exclusively "air" and reveberation.... it is what gives sound a "room-feel".
I am arrogant and I can afford it because I deliver.

How important are frequencies over 13 kHz?

Reply #10 –
oh, my bad

i used dbpoweramp to convert flac to flac, and it uses SSRC to resample, i think it uses 32 bit floating point internally

and i tested it using sennheiser HD 280 headphones, foobar2000 using the kernel streaming output to my creative x-fi expresscard
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #11 –
Don't test audibility of low pass filtering by resampling - you're introducing too many variable, not least: your soundcard may handle different sample rate differently - or equally badly, making "problems" audible at 32kHz which are not at 44.1kHz, for example.


To ipotesi,

This depends on your ears and your speakers/headphones. Whether what you are reporting is "normal" or not depends on your age. It's normal for a 50-60 year old. It's amazingly good for a 70 year old. It's very worrying for a 15 year old! (Unless poor speakers are to blame).

If you're testing this for efficient encoding, 16kHz is the sweet spot for mp3, due to inefficiencies of the format above 16kHz.

Cheers,
David.

How important are frequencies over 13 kHz?

Reply #12 –
Quote from: 2Bdecided on
Don't test audibility of low pass filtering by resampling - you're introducing too many variable, not least: your soundcard may handle different sample rate differently - or equally badly, making "problems" audible at 32kHz which are not at 44.1kHz, for example.


This is true, however i couldn't find an actual low pass filter or something else besides resampling to get the desired effect.

if there is a free high quality low pass filter i would gladly test this again
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #13 –
You can use Sox (sox.sourceforge.net) in the following way from the command line:

sox original.wav lowpass16kHz.wav lowp 16000.0

Alternatively, the Audacity open source audio editor can be used to the same effect.
Dynamic – the artist formerly known as DickD

How important are frequencies over 13 kHz?

Reply #14 –
thanks

I will try a few of these later tomorrow probably
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #15 –
Thanks for all.

I imagine that the song You Really Got Me by Van Halen (1978) is supposed to be a typical one with a lot of stuff over 13 kHz, with all those cymbals and high notes on distorted guitars . A friend of mine has that song on a CD and I ripped the song into my PC as a wav file. I applied a highpass filter at 13 kHz, and a lot of signal survives at >13 kHz. Listening to the highpassed wav, I can hear it as kind of whistles or something penetrating that I am not able to explain. Nothing remains of the real song, apart from the rhythm. I don't know yet if I am able to distinguish the lowpassed song from the full bandwidth song (I have not yet tried this: I should burn a CD and listen to it on a real hi-fi, rather than on the limited stereo output of my PC as I am doing now).

However, I wonder what benefit can be added to the song from hearing those high frequencies...

Ipotesi

How important are frequencies over 13 kHz?

Reply #16 –
Quote
but when I listen to music, I can't notice anything over 12500 Hz: if I make a low pass filter at 12.5 kHz or 13 kHz, I can't tell the original audio from the filtered one.
  Never admit THAT!  They'll kick you out of the audiophile club!   

Quote
I applied a highpass filter at 13 kHz, and a lot of signal survives at >13 kHz. Listening to the highpassed wav, I can hear it as kind of whistles or something penetrating that I am not able to explain. Nothing remains of the real song, apart from the rhythm.
  Many years ago, I was working on a speaker system and I temporarily had only the tweeter connected.  I was amazed at how little sound came out!  It was probably crossed-over at 2kHz or 4kHz (I don't remember).  But, the other way around, with everything but the tweeter connected, it sounded terrible...  very "dull".

Quote
I don't know yet if I am able to distinguish the lowpassed song from the full bandwidth song (I have not yet tried this: I should burn a CD and listen to it on a real hi-fi, rather than on the limited stereo output of my PC as I am doing now).

However, I wonder what benefit can be added to the song from hearing those high frequencies...
  I think the theory is that since the limit of human hearing is about 20kHz, we can be assured of good music reproduction (as far as frequency response is concerned) if the system can reproduce frequencies up to that human limit. 

There are two way of looking at this...  From a "hi fidelity" or "audiophile" point of view, the question is "How good can I make it?"  If I loose some of those high frequencies, maybe someone will hear the loss.    If I can get 96Khz at 24 bits, why not?  If I have plenty of storage space, why not use FLAC or WAV?  Why take a chance with MP3?  If I can make an amplifier flat to 100kHz, why not?  ...Maybe I can sell more amplifiers, or get a higher price if I have "better specs". 

On the other hand, from a "cost" point-of-view, the question is "What can I get-away with?"  If you are running a telephone network, you'd like to use the minimum bandwidth to save costs.  If you have limited digital storage space you might want to minimize the number of bits/bytes used

P.S.
I suppose most people compromise somewhere in the middle...  For example, I don't want to devote the disk space requred for WAV or FLAC files, but I've never done any ABX tests to see how low I could go with MP3 bitrates.  I just use a "high quality" MP3 setting, and I don't think about it.  My files are "good enough" that I don't worry about the quality, and also "small enough" that I don't worry about the disk space.

How important are frequencies over 13 kHz?

Reply #17 –
alright, second batch of ABX, using the first few seconds of the song Pariah by Lamb of God, this is off of a live cd and has plenty of volume in frequencies all the way out to the max resolution of cd audio

first, 18khz, see if i can hear it
Code: [Select]
foo_abx 1.3.3 report
foobar2000 v0.9.5.6
2008/10/01 21:33:38

File A: C:\Documents and Settings\Reed McIntosh\Desktop\10 - Pariah 18khz.wav
File B: C:\Documents and Settings\Reed McIntosh\Desktop\10 - Pariah orig.wav

21:33:38 : Test started.
21:34:03 : 01/01  50.0%
21:34:08 : 02/02  25.0%
21:34:10 : 03/03  12.5%
21:34:13 : 04/04  6.3%
21:34:15 : 04/05  18.8%
21:35:11 : 05/06  10.9%
21:35:26 : 06/07  6.3%
21:35:31 : 07/08  3.5%
21:35:37 : 08/09  2.0%
21:35:41 : 09/10  1.1%
21:35:44 : 10/11  0.6%
21:35:47 : 11/12  0.3%
21:35:51 : 12/13  0.2%
21:35:54 : 13/14  0.1%
21:35:57 : 14/15  0.0%
21:36:05 : 15/16  0.0%
21:36:07 : Test finished.

 ---------- 
Total: 15/16 (0.0%)
alright...19khz
Code: [Select]
foo_abx 1.3.3 report
foobar2000 v0.9.5.6
2008/10/01 21:37:16

File A: C:\Documents and Settings\Reed McIntosh\Desktop\10 - Pariah 19khz.wav
File B: C:\Documents and Settings\Reed McIntosh\Desktop\10 - Pariah orig.wav

21:37:16 : Test started.
21:37:45 : 01/01  50.0%
21:37:50 : 02/02  25.0%
21:37:53 : 03/03  12.5%
21:37:56 : 04/04  6.3%
21:38:01 : 05/05  3.1%
21:38:05 : 06/06  1.6%
21:38:08 : 07/07  0.8%
21:38:10 : 08/08  0.4%
21:38:13 : 09/09  0.2%
21:38:15 : 10/10  0.1%
21:38:18 : 11/11  0.0%
21:38:23 : 12/12  0.0%
21:38:27 : 13/13  0.0%
21:38:30 : 14/14  0.0%
21:38:33 : 15/15  0.0%
21:38:36 : 16/16  0.0%
21:38:39 : Test finished.

 ---------- 
Total: 16/16 (0.0%)
  20khz?
Code: [Select]
foo_abx 1.3.3 report
foobar2000 v0.9.5.6
2008/10/01 21:39:40

File A: C:\Documents and Settings\Reed McIntosh\Desktop\10 - Pariah 20khz.wav
File B: C:\Documents and Settings\Reed McIntosh\Desktop\10 - Pariah orig.wav

21:39:40 : Test started.
21:39:55 : 01/01  50.0%
21:39:59 : 02/02  25.0%
21:40:04 : 03/03  12.5%
21:40:25 : 04/04  6.3%
21:40:28 : 05/05  3.1%
21:40:32 : 06/06  1.6%
21:40:35 : 07/07  0.8%
21:40:40 : 08/08  0.4%
21:40:44 : 09/09  0.2%
21:40:47 : 09/10  1.1%
21:40:50 : 10/11  0.6%
21:40:55 : 11/12  0.3%
21:40:59 : 12/13  0.2%
21:41:02 : 13/14  0.1%
21:41:07 : 14/15  0.0%
21:41:11 : 15/16  0.0%
21:41:12 : Test finished.

 ---------- 
Total: 15/16 (0.0%)

  theres no way, granted im young yet, but i know i cant hear 20khz and beyond...i dont know, i used audacity low pass filter, no resampling, same testing equipment etc.

edit:
http://s484.photobucket.com/albums/rr207/t...periah18khz.png
http://s484.photobucket.com/albums/rr207/t...=periahorig.png

[!--sizeo:1--][span style=\"font-size:8pt;line-height:100%\"][!--/sizeo--]Moderation: Changed "code" to "codebox".[/size]
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #18 –
it depends what are you using for high/low pass. lame's filter will not be same as the sox's or audacity's or whatever... they all use different functions/orders for the filter, just to say.

agreeing with lyx, you'll lose some ambience from the original, and with 2Bdecided: 16kHz is the sweet spot for mp3.

How important are frequencies over 13 kHz?

Reply #19 –
Quote from: Dynamic on
You can use Sox (sox.sourceforge.net) in the following way from the command line:

sox original.wav lowpass16kHz.wav lowp 16000.0

Quote from: 2E7AH on
it depends what are you using for high/low pass. lame's filter will not be same as the sox's or audacity's or whatever... they all use different functions/orders for the filter, just to say.

Indeed, the sox lowp filter rolls off at only 6dB/octave which is not enough for this test.  It has another filter though that allows steepness setting. e.g.

sox original.wav lowpass16kHz.wav filter -16000 2500

The higher the last number, the steeper the filter.  In the above example, it's very steep: the stopband (-150dB) starts at around 16100 Hz.

  -bandpass

How important are frequencies over 13 kHz?

Reply #20 –
thanks bandpass, ill give it a try
My $.02, may not be in the right currency

How important are frequencies over 13 kHz?

Reply #21 –
I have done more tests, with better earphones on my PC and I was able to hear single tones up to 18000 Hz!
Not only: I have ABXed the above song by Van Halen, from the same lowpassed at 13.2 kHz, with the new earphones, and minimizing the noises around.
In the ABX test, the wrong guesses were 5 out of 30 (probability of chance <<0.1%): this result (25 out of 30) is highly significant, even if I am not able to be right all the times.

That said, I am more happy about my ears, but I still wonder why and how those frequencies can be beneficial to a good listening experience. I am already happy without those high frequencies. A cutoff at 12.5 kHz continues to be good for me, and I don't need more. Even if I have found that I can ABX a lowpass at 13.2 kHz, the richer audio adds nothing to my music experience!

Finally, I would like to ask a question, but it may seem a nonsense.
The question is: if you must choose an ideal cutoff (lowpass frequency), which one would you choose?
The question will not make sense for many people, because a 20 kHz band costs nothing, so why should I choose a lower cutoff? Despite the question is illogical, I feel I can give an answer, that would be 12.5 kHz.

If you don't understand what I mean: think of a new crazy law made by the Government, stating that everyone who has X Gigabyte of compressed music (say 10 GB), suddenly must have only half that amount (5 GB in this case) and nothing more. Then most people, to keep more of the best songs, would compress more their files, lowering the bitrate, and hence lowering the cutoff frequency, to keep as many songs as possible into the 5 GB. So, in this crazy scenario, my question may have a sense: what cutoff frequency would you choose as the better compromize with saving the higher number of songs?
(For those who just refuse the question: I will understand).

Ipotesi

How important are frequencies over 13 kHz?

Reply #22 –
i think lyx said it all, but if you wish to try yourself then abx diamanda galas's "plague mass". it's live in the one of the greatest cathedral "st. john the devine" n.y. with great engineering. i'll try abx on that but i got the album on lp.

and about your question on lowpass freq. it all depends of the recording music and your ears.

How important are frequencies over 13 kHz?

Reply #23 –
For being able to discuss the results in here, one would probably want:
1. The ABX score
2. A frequency analysis of the program material
3. An estimate of the playback equipment frequency response
4. A complete description of the lowpassfilter (not only the cutoff frequency, but the set of FIR/IIR coefficients, or a detailed frequency/phase response diagram)

Question:
What is the "best" filter characteristic to test this? I would imagine a linear-phase FIR filter with reasonably sharp cutoff. But if the question is "what sampling rate is necessary for the given public as a mean across all implementations of AD, DA and SRCs?", then I would be clueless.

By the way, one requirement for sine-stimulus to be representative in all cases is that the hearing is linear.

From at Ph.D-thesis I just happenend to be skimming through:
http://lib.tkk.fi/Diss/2001/isbn9512254603...n9512254603.pdf
Quote
The human ear can perceive frequencies up to 20 kHz (Fletcher 1953). Muraoka, Iwahara
& Yamada (1981) studied perception of reduction in bandwidth of musical signals.
They found that most people hear the difference between full audio band and 14 kHz
band but only few can hear the difference if the bandwidth is restricted to 18 kHz. In
modern audio systems, typical audio bandwidths are above 20 kHz. It is usually assumed
that sufficient bandwidth for speech is 10 kHz 7

Fletcher, H. (1953), Speech and Hearing in Communications, Van Nostrand, Princeton, USA.
Muraoka, T., Iwahara, M. & Yamada, Y. (1981), ‘Examination of audio-bandwidth requirements for optimum sosuns
signal transmission’, J. Audio Eng. Soc. 29(1/2), 2–9.


-k

How important are frequencies over 13 kHz?

Reply #24 –
Quote from: knutinh on
Question:
What is the "best" filter characteristic to test this? I would imagine a linear-phase FIR filter with reasonably sharp cutoff.


There's an article here that suggests that linear phase is not so good -- thoughts?

  -bandpass