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Computer Audio Asylum: RE: 44.1 kHz shown scientifically to be inadequate by Tony Lauck

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RE: 44.1 kHz shown scientifically to be inadequate

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"My basic theory now is that playback of higher res music has inherently less jitter and timing errors in absolute terms. And that's primarily why it sounds better on the average high-jitter playback system. It's NOT having more samples to work with."

I normally playback 44.1 kHz material by upsampling to 176.4 kHz as it sounds better that way to me. However, the results are not as good as playback of 88.1 material (or 176.4 material of which I have little). So I don't think differences in the playback chain account for the whole story.

I have done a simple test to isolate degradation due to format/conversion from degradation due to limitations of playback gear:

1. I started with a good sounding 88/24 recording in a first file. (I took care that the file has no peaks too close to 0 dBfs, so that the sample rate converters won't clip on an inter-sample peak.)

2. Using a high quality sample rate converter, I produced a second file in the 44/16 format from the first file.

3. Using a high quality sample rate converter, I produced a third file in the 88/24 format from the second file.

4. I then auditioned the first and third files, using the exact same hardware and software.

In this comparison, the only possible cause of an audible difference between the files comes from the limitations of the format itself and any weaknesses in the sample rate converter(s). I got good results using Izotope RX Advanced, with a setting that avoided any aliases or images above 22050 Hz, had relatively slow roll off and was minimum phase. However, on many recordings, especially the ones I judged to be best, the first and third files did not sound the same, although the differences were subtle.

(Note that if you do this test and do not hear a difference then it would be improper to conclude that 44/16 and your converters are transparent, just that they were transparent with the recordings tested, on your system, with your ears and with your present level of experience and concentration.)

Repeating the test using 44/24 for the second file produced similar results. Using 48/24 the results were less clear cut, as expected because the degradation will be less in both the frequency and time domains.

Before doing these tests I had been of the opinion that the bit depth accounted for much of the difference between hi-res and 44/16. After doing these tests, I no longer believe this is the case. In my opinion, most of the degradation due to 44/16 comes from the sampling rate and not the bit depth, at least with recordings that are fully utilizing the available 16 bits.





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Topic - 44.1 kHz shown scientifically to be inadequate - Tony Lauck 19:26:14 07/26/09 ( 72)