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With the sudden proliferation of brainwave entrainment audios on Youtube, certain companies, in an attempt to compensate for diminished traffic to their web stores have attempted to discredit channels like ours, claiming that once uploaded and subjugated to the process of audio compression, Youtube audios are no longer effective. Let’s put this claim to the test shall we?
There are two stages to encoding a track to be uploaded to Youtube. First there is the initial rendering process, where the video file is compressed down to a size that won’t take days to upload. During this stage, the audio can remain uncompressed, leaving this task to Youtube’s automated encoding process. Youtube transcodes uploaded content in order to make it suitable for streaming, and readily available to a wide audience on devices such as mobile phones, tablets, notebooks and PCs.
The range of human hearing is approximately between 20hz – 20khz. Encoders work by removing certain frequency content in order to reduce file size. How is it determined exactly which frequencies to remove?
Well, when listening to CD quality audio, or uncompressed FLAC files for example, not all frequencies are perceivable to the human ear, particularly those on the extremes of the spectrum. We can take these away and the difference will be unnoticeable.
At The Brainwave Hub, we send uncompressed PCM audio to Youtube’s converters just for the sake of presentability, but what if you were to upload an already-compressed MP3 file for further transcoding?
LET’S TRY AN EXPERIMENT
In this experiment we’ll render two identical binaural beat tracks – one in uncompressed WAV format, and the other as an MP3 file (41,000 Sample Rate, 320kbps Bit Rate). We’ll then load these into a spectral analyser. We would never upload an MP3 to Youtube but the following experiment will show how commonly used data compression does not inhibit an entrainment session.
Here are two sine waves – 200hz & 210hz…
Binaural beats work by combining these two tones, the difference of which is used to create a third ‘ghost’ beat inside the head. For this to occur, the tones must be panned hard left and right respectively.
The spectral graphs below will show the WAV and MP3 files’ frequency content before and after conversion by Youtube’s servers.
Uncompressed WAV Exported from Audacity (BEFORE YOUTUBE CONVERSION):
Compressed MP3 Exported From Audacity (BEFORE YOUTUBE CONVERSION):
As you can see, the fundamental frequencies (200-210hz) of the MP3 are still intact. The frequency response graph is pretty much identical, with any difference being aurally and visually undetectable.
Let’s take it a step further and upload that uncompressed WAV file to Youtube before once again analysing the frequency content…
After Youtube conversion:
Yes that’s right, there is absolutely no vital frequency loss and the audio is once again identical to the one which passed through the initial render process. And guess what? The same result was achieved by uploading an already compressed MP3 file to Youtube, including one featuring isochronic tones. The spectral analyser shows the exact same response curve.
FUNDAMENTAL FREQUENCIES
Let’s hammer home the point a little further…
With pure sine waves, we are dealing with very basic forms of audio, specifically the fundamental frequencies which provide a base tone for more complex waveforms, such as those found in musical instruments.
Sinewave:
For example, with a violin, it is the addition of harmonics and overtones which give a violin its signature sound.
Compare the above spectral graphs to this one of an acoustic guitar ‘A’ string being plucked:
Not only does an ‘a’ string have a fundamental note of 110hz (in 440hz tuning), but many harmonic overtones accompany it in order to create the guitar sound we’re familiar with, including 220hz, 440hz etc. With the pure-tone sine waves above, we have the basic fundamental ‘spike’ only.
“So why do I need to know this?”
Because when administering data compression to binaural beats or isochronic tones, you don’t have to worry about the preservation of complex frequency content, i.e. harmonics and overtones, for their effects to be felt – because there aren’t any. You would have to run a track repeatedly through poor quality converters at stupidly low bit/sample rates to render the final result an indistinguishable, mangled mess littered with artefacts.
WHAT ABOUT BINAURALS COMBINED WITH MUSIC?
Musical tracks consist of an abundance of harmonic overtones, but as mentioned earlier, the majority of the frequencies lost when converting to MP3 or uploading to youtube will be on the extremes ends of the audible spectrum and therefore barely noticeable. Any minor degradation that does occur from data compression does not influence the efficacy of the fundamental sine waves which form the basis of an entrainment session, providing both elements are mixed properly and there is a good balance between them.
When mixing pure sine waves with music for example, there exists a clashing of frequencies where the basic fundamental tone is drowned out by the overtones of the musical backdrop. This is something that has been overlooked by most Youtube channels, rendering audios advertised as brainwave entrainment as innefective, with no frequency-following-response possible. If what you’re after is just background music then that’s fine, but you’re not getting authentic brainwave entrainment audio. Luckily we use advanced audio mixing techniques to distinguish between binaurals/isochronics and prevent any possible unwanted interactions between the music and pure tones.
CONCLUSION
When dealing with binaural beats and isochronic tones, MP3 or Youtube data compression is nothing to be concerned about due to the simplicity of their fundamental tones.
In our MP3 store, files are rendered at the highest quality possible; 320kbps and 48000hz just for presentability. Lower settings can be used but we find that most people don’t mind the slightly bigger MP3 file sizes. Regarding Youtube, uncompressed WAV files may take a little while longer to load but with the majority of internet owners having access to a steady broadband connection these days, this isn’t a problem.
Combined with music, and mixed correctly, binaurals and isochronics will retain their efficacy. Musical content will experience minor, almost imperceptible degradation in fidelity due to its wider harmonic content (this doesn’t stop iTunes, Spotify etc.), but the efficacy of brainwave entrainment will not be compromised unless silly levels of data compression are applied. Music was only ever meant to be a masking tool anyway, to make the fundamental entrainment tones more palatable.
Thank you for reading; I hope this article has helped clear up a few of the myths surrounding data compression on MP3s and Youtube audios.