Fidelity and Resolution

This is Part Three of a post on the journey of my music listening from high-fidelity to mobile phone earbuds and back again.  You should probably go back and read Part 1 and Part 2.  Or not.

earbudsAt the end of Part 2, I was listening to music stored in the MP3 format on my smartphone, happy as the proverbial pig to have my music portable where I could listen as loud as I wanted.   But I kept seeing articles about high resolution audio online.   Neil Young, of all people, made a passionate plea to save music through his high resolution  player and streaming service, Pono (since abandoned).   Other articles sing the praises of so-called lossless compression formats like FLAC and ALAC.  On Amazon, I found pocket devices claiming to be high resolution music players ranging in cost from $25 to almost $4000.  Even given the tendency of audiophiles to equate high cost with high fidelity, that seemed suspicious.   Suspiciously, too, I can find articles claiming high-resolution audio is anything from audio Nirvana to practically a scam.  So just what is high resolution audio?

To answer that, we need to know a just a little about digital recording (If you are an electrical engineer you can skip this part).  The sound of music is what is called an analog time series, a continuous stream of sound of varyingsample loudness that is converted to a continuous electrical signal by microphones. As studio recording equipment got better, the primary limit on fidelity of the recording was how accurately the signal could be impressed on vinyl or magnetically represented on tape.  The CD revolution sampled the analog signal at a very high rate (the sample rate) and quantized it to 2N discrete levels.  The number N is known as the resolution of the sampler, or the bit depth.  Put simply, the higher the sample rate and bit depth, the more accurately the digital signal represents the analog.  Sample rate primarily affects the frequencies retained in the digital signal … frequencies higher than half the sample rate are lost.  CDs utilize a sample rate of 44.1 kHz and a 16-bit linear bit depth.   This allows accurate representation of signals up to 22 KHz, the limit of human hearing.   Studio Master files, though, are encoded at 24-bit or higher, and currently up to 192kHz, virtually identical to the analog signal.

The catch, of course, with respect to being able to carry around lots of music in our portable devices is that the higher the bit rate and sample rate, the larger the digital files.  Enter data compression.  Lossless compression, like FLAC, digitalencodes exactly the data in the original digital recording using only the bit depth necessary to represent the samples, so that quiet passages in the music require less storage.  The MP3 files we’ve learned to love (or hate) go one step farther.  By eliminating or approximating certain aspects of the recorded music that most people cannot hear (heresy to audiophiles), then compressing the resulting data, the size of an MP3 file for a song can be reduced as much as 95% in comparison to the file on a CD.   It is in fact remarkable that MP3 files sound as good as they do, hence the wide acceptance of the format.   And there is a middle ground.  MP3 recordings with a higher bit rate have markedly improved sound, and most sources say using a 320 KBps bit rate yields music that is indistinguishable from CDs.

So, should you take the plunge to so-called high-resolution?   I like what Wikipedia says about high definition audio … it is a marketing term used by some recorded-music retailers and high-fidelity sound reproduction equipment vendors. It refers to higher than 44.1 kHz sample rate and/or higher than 16-bit linear bit depth.  That says nothing about fidelity, which is testhow good the music sounds … which depends on the listener.   I took a simple hearing test online at noiseaddicts.com and discovered I could not hear a 12kHz tone.  A CD on a quality system can produce sounds out to 22KHz, so it is unlikely that I’m one of those who can hear the difference in a studio recording.  If you are a music lover, it certainly makes sense to have your music files sound as good as a CD since that can be done with some modest changes.   Beyond that is questionable.  An excellent (and very technical) article on xiph.org, Is high-resolution audio really as good as it sounds? concludes, Why push back against 24/192? Because it’s a solution to a problem that doesn’t exist, a business model based on willful ignorance and scamming people. The more that pseudoscience goes unchecked in the world at large, the harder it is for truth to overcome truthiness… even if this is a small and relatively insignificant example.  Meanwhile companies (like Crutchfield) marketing high-resolution audio will tell you,  The performance is spread out before you, complete in every detail. The singer takes a breath between phrases, the guitarist’s fingers squeak lightly as they travel up the fretboard, and the drummer coaxes a delicate, shimmering rhythm from his ride cymbal. Sure, you need good equipment to hear these nuances, but you also need a high-quality source. This is why we’re still excited about high-resolution audio. With a level of sonic detail that’s better than CD, downloadable high-res music files can deliver sound so real, you feel like you’re sharing the studio or the stage with your favorite musicians.

You can read all you want, but your ears will tell you what is the truth for you.  I took a moderate plunge with an AGPTEK H3 HIFI High Resolution Lossless Digital Audio Player and  a pair of  1MORE Triple Driver In Ear Headphones.  I’ll report on my experiences with them in the next (and final) post in this series. A little philosophy, too.

 

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