High-Frequency Noise in CD Recordings

jdgonko · 28th November 2007, 07:02 AM

Hello. After asking a highly knowledgeable friend, I've decided to ask the forum.

Why do I see a low-level frequency 'line' (FFT derived) during many recordings which appears to be around the 16KHz range? Moon Over Bourbon Street (Sting) on the Bring on the Night Disc 2 has it. Cosmic Thing (B-52's) on the Cosmic Thing disc has it to a lesser degree. Take Me To The River (Talking Heads) on the Sand in the Vaseline Disc 1 has one around 20KHz.

I cannot easily locate all the songs where I have noticed this phenomenon but it's there frequently and constantly. But why?

Did something go awry in during the recording session??

Thanks,
Joe

es44 · 28th November 2007, 07:16 AM

Interesting question.
I've noticed the same with different cd's, and i will listen in on this, as i have no clue what does it.

best regards
Ebbe

jdgonko · 28th November 2007, 07:52 AM

My only assumption is that the 'spurious' data/frequency is:

(1) From a malfunctioning recording device
(2) From an inessential device emanating frequency in the studio
(3) Some sort of psychoacoustic addition to the recording

What do you think? I am seeking any and all thoughts on this.

Thanks,
Joe

dnsey · 28th November 2007, 08:14 AM

I became aware of this when first hearing CDs, and shopping for my first player. I likened it to a 'TV line whistle'

Although I could hear the noise clearly (and initially assumed that it was inherent in the CD system), none of the salesmen demonstrating the equipment claimed to be able to hear it!
At that time, it seemed to be a problem with virtually all CDs.

These days, I hear it less often - but perhaps that's just due to deterioration in my hearing.

I do wonder if it's this phenomenon which some listeners liken to 'fingernails down a blackboard'.

jdgonko · 28th November 2007, 08:28 AM

Well, I admit that high frequencies are harder to hear due to my age, attendance of many loud concerts at First Avenue (Minneapolis), and in possession of full-range output high-quality devices, but I have become curious to know why they are there.

Perhaps an audio engineer will provide the answer?

BTW, I can still always tell when a muted TV is on due to its inherent 'squeal.' haha

Thanks!
Joe

FrankWW · 28th November 2007, 08:33 AM

Quote:

Why do I see a low-level frequency 'line' (FFT derived)

How far down is this signal? Can you post an example?

dnsey · 28th November 2007, 09:15 AM

IME, it's modulated by the music signal - i.e. quite audible over loud passages, but rarely so during silence.

Pulse-R · 28th November 2007, 09:16 AM

If you're talking about the peaks at -92 to -100dB, this is caused by dithering techniques.

An interesting example can be found on the "Best of Chesky Classics & Jazz and Audiophile Test Disc Volume 3". Tracks 40 to 44 demonstate different dither levels, and you can see the peaks in the top end of the spectrum change with different dither, 16 bit, 20 bit and "high resolution" dithers.

es44 · 28th November 2007, 12:42 PM

Funny thing. I had the same thought about the tv-line frequency, when i saw it the first time. It's very close indeed.
Admitted, i can't hear it either, but i can see it in Cool Edit, when i look at a sample. A clear spike a little over 16Khz.

very strange

Dan2 · 28th November 2007, 01:39 PM

i have also heard that high pitch on dvd's, usually when there is just someone speaking, and its audible on my "cheap" dvd player and on my computer. its not throughout the movie, and not with all movies either

28th November 2007, 07:02 AM	#1
jdgonko diyAudio Member Join Date: Dec 2005 Location: Minneapolis, MN	High-Frequency Noise in CD Recordings Hello. After asking a highly knowledgeable friend, I've decided to ask the forum. Why do I see a low-level frequency 'line' (FFT derived) during many recordings which appears to be around the 16KHz range? Moon Over Bourbon Street (Sting) on the Bring on the Night Disc 2 has it. Cosmic Thing (B-52's) on the Cosmic Thing disc has it to a lesser degree. Take Me To The River (Talking Heads) on the Sand in the Vaseline Disc 1 has one around 20KHz. I cannot easily locate all the songs where I have noticed this phenomenon but it's there frequently and constantly. But why? Did something go awry in during the recording session?? Thanks, Joe

28th November 2007, 09:16 AM	#8
Pulse-R diyAudio Member Join Date: Mar 2005 Location: Melbourne	If you're talking about the peaks at -92 to -100dB, this is caused by dithering techniques. An interesting example can be found on the "Best of Chesky Classics & Jazz and Audiophile Test Disc Volume 3". Tracks 40 to 44 demonstate different dither levels, and you can see the peaks in the top end of the spectrum change with different dither, 16 bit, 20 bit and "high resolution" dithers. __________________ Digital is only on or off

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28th November 2007, 07:16 AM	#2
es44 diyAudio Member Join Date: Apr 2005 Location: Fredericia, DK	Interesting question. I've noticed the same with different cd's, and i will listen in on this, as i have no clue what does it. best regards Ebbe

28th November 2007, 07:52 AM	#3
jdgonko diyAudio Member Join Date: Dec 2005 Location: Minneapolis, MN	My only assumption is that the 'spurious' data/frequency is: (1) From a malfunctioning recording device (2) From an inessential device emanating frequency in the studio (3) Some sort of psychoacoustic addition to the recording What do you think? I am seeking any and all thoughts on this. Thanks, Joe

28th November 2007, 08:14 AM	#4
dnsey diyAudio Member Join Date: Mar 2004 Location: Shropshire, England	I became aware of this when first hearing CDs, and shopping for my first player. I likened it to a 'TV line whistle' Although I could hear the noise clearly (and initially assumed that it was inherent in the CD system), none of the salesmen demonstrating the equipment claimed to be able to hear it! At that time, it seemed to be a problem with virtually all CDs. These days, I hear it less often - but perhaps that's just due to deterioration in my hearing. I do wonder if it's this phenomenon which some listeners liken to 'fingernails down a blackboard'.

28th November 2007, 08:28 AM	#5
jdgonko diyAudio Member Join Date: Dec 2005 Location: Minneapolis, MN	Well, I admit that high frequencies are harder to hear due to my age, attendance of many loud concerts at First Avenue (Minneapolis), and in possession of full-range output high-quality devices, but I have become curious to know why they are there. Perhaps an audio engineer will provide the answer? BTW, I can still always tell when a muted TV is on due to its inherent 'squeal.' haha Thanks! Joe

28th November 2007, 09:15 AM	#7
dnsey diyAudio Member Join Date: Mar 2004 Location: Shropshire, England	IME, it's modulated by the music signal - i.e. quite audible over loud passages, but rarely so during silence.

28th November 2007, 12:42 PM	#9
es44 diyAudio Member Join Date: Apr 2005 Location: Fredericia, DK	Funny thing. I had the same thought about the tv-line frequency, when i saw it the first time. It's very close indeed. Admitted, i can't hear it either, but i can see it in Cool Edit, when i look at a sample. A clear spike a little over 16Khz. very strange

28th November 2007, 01:39 PM	#10
Dan2 diyAudio Member Join Date: Sep 2005	i have also heard that high pitch on dvd's, usually when there is just someone speaking, and its audible on my "cheap" dvd player and on my computer. its not throughout the movie, and not with all movies either

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