High Resolution Audio vs CD
Over the past few months you have heard us mention high resolution audio on the show. There are audiophiles out there that swear that if you want the best quality audio then you must listen to high resolution audio. Others out there will tell you that CD quality is just as good. Then there are some that say mp3 or AAC files will suffice for the kind of listening most of us do.
On today’s show we will take both an objective and subjective look at the subject. But this will be a different type of show this week. We’ll discuss the subject on the podcast but there is a companion video that will greatly help in the understanding of the topics discussed. Its available on our Youtube channel (HT Guys) or you can find it embedded on the website for today’s post.
Before we get into the discussion let’s define a few terms for the purposes of our discussion:
Hi-Res Audio – (From Wikipedia) There is no standard definition for what constitutes high-resolution audio, but it is generally used to describe audio signals with bandwidth and/or dynamic range greater than that of Compact Disc Digital Audio (CD-DA). This includes pulse-code modulation (PCM) encoded audio with sampling rates greater than 44100 Hz and with bit-depths greater than 16, or their equivalents using other encoding techniques such as pulse-density modulation (PDM).
High-resolution audio file formats include FLAC, ALAC, WAV, AIFF and DSD, the format used by Super Audio Compact Discs (SACD). It should be noted, however, that audio encoded into one of these file formats is not necessarily high-resolution audio. For example, a WAV file could contain audio sampled at 11,025 Hz and quantized at eight bits, which is lower quality than CD-DA.
CD Audio – (From Wikipedia) Digital audio encoding: 2-channel signed 16-bit Linear PCM sampled at 44,100 Hz.
For the objective comparison we start out with a Hi-Res audio file (24 bit 96KHz Sample Rate) and then we encode a CD version (16 bit 44.1KHz Sample Rate) from that. We also created 256Kbps AAC file from the CD version for the subjective test. We imported the 24 bit version into Audacity then we did the same but inverted the track. If the files are identical they should cancel out and the only thing you would hear is silence. That is exactly what happened.
The next step was to import the both the 16 and 24 bit files and then invert the 24 bit track. We expected to see a difference but not by much. What we saw was a resultant audio track with audio from 14KHz to 20KHz. The audio was not loud enough to hear. Our conclusion is that the two tracks are virtually identical.
For this portion of the test we used an application called ABX. ABX is a cross platform (Java Required) blind audio test application that makes this type of testing fool proof. Our setup was a Macbook Pro, Audio Engine D1 24bit DAC (Buy Now $169), and Bowers and Wilkins P5 Headphones (Buy Now $250). While not audiophile territory, it’s a far cry from earbuds connected to your phone.
We had friends and colleagues listen to the Hi-Res vs the AAC file and we found that Ara and two self proclaimed audiophiles were able to hear a difference between these files about 70% of the time. The remainder of the participants could not hear a difference . No one could hear a difference between the 24 and 16 bit audio tracks.
Is this a conclusive test? Not really. We will never say that no one can hear a difference between hi-res audio, CD, and AAC/mp3. So much has to do with the quality of the recordings, the hearing of the listener, and the equipment being used.
On the video we import some music that has been mastered since the loud wars started (late 90s) and it’s pretty obvious that there is not much dynamic range. Do you really need 24 bits when everything is maxed out? If you are used to listening to music that is loud with little or no dynamic range then you listen to something that is pure and full of dynamic range you are amazed. Truth be told you would be impressed even if you weren’t listening to a hi-res recording. When there are just a few instruments and a vocal you can hear everything including little nuances in the recording. That’s why almost every demo I have heard used artists like Norah Jones or Chris Botti. Its because their music has a lot of dynamic range and the detail in the recording usually blows you away. You can also get that detail with CD quality while saving some money and being just as blown away.
Our recommendation is that you rip your CDs in two formats. Do a lossless version for listening at home in a dedicated environment. Then create a compressed version for your portable devices. If you try the test and can’t hear a difference then just go compressed. If you try the test and you can hear a difference, congratulations on having some fantastic hearing skill. This is a blessing and a curse.
Finally, don’t get so caught up in listening at the music to find flaws or a reason to not be happy. You can spend thousands of dollars to diminishing returns. Instead do some simple things like listen in an environment that is comfortable and noise free. Pour yourself a drink and let the sounds take you away to someplace that makes you happy and stress free.
Posted by The HT Guys, July 3, 2015 1:20 AM
About The HT GuysThe HT Guys, Ara Derderian and Braden Russell, are Engineers who formerly worked for the Advanced Digital Systems Group (ADSG) of Sony Pictures Entertainment. ADSG was the R&D unit of the sound department producing products for movie theaters and movie studios.
Two of the products they worked on include the DCP-1000 and DADR-5000. The DCP is a digital cinema processor used in movie theaters around the world. The DADR-5000 is a disk-based audio dubber used on Hollywood sound stages.
ADSG was awarded a Technical Academy Award by the Academy of Motion Picture Arts and Sciences in 2000 for the development of the DADR-5000. Ara holds three patents for his development work in Digital Cinema and Digital Audio Recording.
Every week they put together a podcast about High Definition TV and Home Theater. Each episode brings news from the A/V world, helpful product reviews and insights and help in demystifying and simplifying HDTV and home theater.