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Why Do CDs Sound Louder Than High-Res Audio?

Al Griffin  |  Sep 1, 2016

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Q I recently bought High-Res Audio downloads of Fleetwood Mac’s “Rumours” and Supertramp’s “Crime of the Century” from HDtracks. When I play them with my Sony NWZ-A17 Walkman, the volume is much lower than what I hear from FLAC versions of the same music ripped from my CDs. I complained to HDtracks and they said this was normal for HD-resolution files. Can you explain why? —Jacques Simard

A There are two main things going on with High-Res Audio (HRA) files that differentiate them from audio CDs. The first is that HRA is sampled at a higher rate — typically 96kHz or 192kHz compared with the CD format’s 44.1kHz. This higher sampling rate delivers a higher range of recorded frequencies. The second is increased bit depth: While CDs are recorded with 16-bit bit resolution, the bit depth for HRA is typically 24 bits, with the result that files have a higher dynamic range.

Although the CD format’s 44.1 kHz sampling rate is sufficient to cover the 20Hz - 20 kHz human hearing spectrum, some scientists and engineers, not to mention audiophiles, assert that the extended frequency range provided by HRA can affect sound quality, even if the ear isn’t capable of hearing those frequencies. Meanwhile, the increase in dynamic range provided by bumping resolution up to 24 bits creates a greater sonic difference between soft and loud passages in music.

While the higher dynamic range of HRA can account for one reason why HD downloads have a lower volume level than versions ripped from CDs, another, more likely, reason is that many CD releases of classic rock records were remastered to have a higher overall volume level. It was common music industry practice from 1990 through the early 2000s—an era when major music labels transferred their back catalogues to the CD format en masse—to employ dynamic compression to make tracks sound “louder.” (Click here to learn about the “Loudness War,” and efforts to reverse the trend.)

So, while it’s difficult to fully diagnose your situation without knowing which CD releases we’re dealing with (both titles have been remastered several times), the difference in volume level that you’re hearing is most likely due to: 1) the high-res versions having a higher dynamic range; and 2) lower compression (services such as HDtracks generally make an effort to source content from original master tapes, as opposed to later remasters, especially for high-profile releases like the ones you cite).

COMMENTS
WALTER BRAZIL's picture
Submitted by WALTER BRAZIL on September 1, 2016 - 3:59pm

It is due to the high dynamic range of 24 bits that the High-Resolution Audio system supports higher recording levels than the CD (16bit, Red Book literature), and not as was erroneously reported to Mr. Jacques Simard. If the actual Supertramp Hi-Res recording have a lower level of volume is just a personal choice of the sound engineer who made the transfer of the original recording to Hi-Res system, or even a lack of experience on this new audio format.

hk2000's picture
Submitted by hk2000 on September 1, 2016 - 8:56pm

I agree. I don't believe a higher sampling rate of the same source results in a louder recording. I can't believe they gave you that answer- I guess they assume audiophiles, especially one who already fell for their marketing, will accept any BS they give him. And BTW, this hypothesis about higher frequencies (above 20khz) affecting what we're hearing is just that- there is no proof! HDtracks and the like are just marketers who are maximizing their profit from naive 'audiophiles'.

Al Griffin's picture
Submitted by Al Griffin on September 2, 2016 - 5:40am
that a higher sampling rate results in a louder recording. Please read the response again.
hk2000's picture
Submitted by hk2000 on September 2, 2016 - 6:18am

Sorry, I did not mean you, you actually explained it well. By 'they', I meant HDtracks who implied to their customer that HRA is inherently quieter- I guess they assume audiophiles associate quieter with less noisy and thus higher quality. What I'm trying to say is that HDtracks was being dishonest with their answer since neither higher sampling rate nor higher bit depth can explain this. Even higher dynamic range cannot explain it, for although the quieter passages will be at lesser volume, the peaks will be at much hgiher volume, and you end up with the same loudness level if the source is the same as that of the CD recording.

mtymous1's picture
Submitted by mtymous1 on September 3, 2016 - 5:41am

@hk2000

Porch dog comments aside, have you actually done any trials with HRA?

You may find this link interesting:
www.soundliaison.com/all-categories/6-compare-formats

...where they give you "...a zip file containing samples of 2 tracks in 4 different formats.

A: 96/24 WAV
B: 96/24 FLAC
C: 16/44 WAV (CD)
D: 320kbps MP3

All the different formats have the same source file 96/24 WAV (Studio Master)."

It also goes on to say:
"When you compare the files start with the lowest resolution: D (MP3 320 kbps) and move on up through example C and B ending with A.

Be careful: If you start with A, and move down through B and C ending with D, your mind will remember the ''Blueprint'' of the higher resolution file, making it difficult to hear the difference even when finally listening to the MP3 file. Don't be frustrated if you can't hear a difference at first. Hearing is as individual as taste but hearing is also something which can be acquired, like the taste of good wine."

In your response, I'd also like to hear about the equipment in your HRA delivery stream.

mjgraves's picture
Submitted by mjgraves on September 2, 2016 - 7:54am

It's very likely that in transferring from analog masters to HRA the engineer would seek to preserve transients by mixing the entire album lower than the original. Also, using less compression as has been noted already.

The HRA medium is quieter. That is, the noise floor is well below that of a red book master. That means that the music can be recorded lower, allowing headroom for transients, without meaningfully degrading the overall s/n ratio.

boulderskies's picture
Submitted by boulderskies on September 8, 2016 - 6:46am

I've been reading about Hi-Rez recording and playback since its inception and I dont think I've ever read this about it (author's words): “…The first is that HRA is sampled at a higher rate — typically 96kHz or 192kHz. This higher sampling rate delivers a higher range of recorded frequencies (extended frequency range)…the bit depth for HRA is typically 24 bits, with the result that files have a higher dynamic range.”

Can you explain specifically why these two results occur?

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