Sep 25 Podcast #967: Hearing Loss and Hi Res Audio
On this week’s show we ask if you would be OK sharing your wifi with your neighborhood as part of a Mesh network to improve the reliability of your wireless devices. That’s what Amazon wants to do with the project Sidewalk. We also discuss Hi Res Audio and old folks hearing. Are these recordings in Hi Res format worth it? As usual we read your emails and check out the news of the week.
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Today's Show:
News:
- Hulu tests its co-viewing feature ‘Watch Party’ with ad-supported viewers
- HDHomeRun now has a native app for Apple TV
- Apple TV, 4K YouTube lack compatibility
- Old TV caused village broadband outages for 18 months
Other:
Amazon will launch a new location-tracking mesh network system later this year
Amazon is preparing to launch an ambitious networking and location system later this year under the name Amazon Sidewalk. Sidewalk will link smart home devices and other Amazon products using Bluetooth Low Energy (BLE), connecting beyond the range of a standard Wi-Fi network.
Meant to be operated at the scale of a neighborhood, Sidewalk would turn devices like smart floodlights and home assistants into network bridges, passing along security updates and commands from a central Wi-Fi hub. In addition to transmitting software, the signals allow Sidewalk to triangulate a device’s approximate location based on its contacts with other Sidewalk-enabled devices.
The system will be built into the Echo, and Tile has also joined the project as the first third-party platform to support the system. Amazon plans to add Ring cameras to the network later, notifying device owners directly when Sidewalk is available to use. A full list of Sidewalk-compatible devices is available on the project landing page. More info here...
Hearing Loss and Hi Res Audio
A good friend of ours sent us a link to a Youtube video called “Hearing Loss at Age”. This video tries to explain the physical degradation of hearing as we age. The video was produced by Hans Beekhuyzen a Dutch Hifi expert and member of the Audio Engineering Society.
The video is a little technical but essentially says that as we age we can not hear the upper octave of the ten octaves between 20 Hertz to 20kHz. That tenth octave starts at 16.7kHz. He says not worry because we still hear 90% of the sound spectrum. So why do we need Hi Res files? We’ll get to that.
He mentions Nyquist in this video to discuss sampling. This is where the video gets quite technical. He has another video that goes into much more detail about this subject (The truth about Nyquist and why 192 kHz does make sense).
What is Nyquist?
It is named after electronic engineer Harry Nyquist. Nyquist's theorem states that a periodic signal must be sampled at more than twice the highest frequency component of the signal. In practice, because of the finite time available, a sample rate somewhat higher than this is necessary. Since we want to sample sound up to 20Khz, for those of us lucky enough to hear sound at that frequency, the sample rate should be no lower than 40Khz.
Just for completeness, sampling is a representation of sound recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is encoded as numerical samples in a continuous sequence. For example, in CD audio, samples are taken 44100 times per second each with 16 bit sample depth. We’ll cover sample depth in a bit
If a CD is sampled at 44.1Khz. That means it can recreate frequencies up to 22.05Khz, far above what people can hear! So we’re all good right? Again why do I need Hi Res Files?
Sampling Errors
One of the issues with sampling is that it's not perfect and there are errors. This is where the video lost me because I am not an electrical engineer. We’ll try to sum it up here. There is an error that is induced because of the sampling rate and that error can show up in the audio spectrum that you can hear. Filtering can reduce this but that too affects the sound as well.
The solution is that you can sample at a higher frequency. Hi res files are sampled at 192Khz. That means technically it is capable of capturing frequencies up to 96Khz which is way above what any human can hear. However, there is a benefit in that the errors that are created fall outside what the human can hear. Thus leaving you with a more pure recording of the original signal. There is a price to be paid for this, the file size is much bigger.
Bit Depth
The other element to this discussion is bit depth. The bits store the amplitude of the sound wave. CDs use 16 bits which equate to 65536 possible values. Hi res files use 24 bits or 1,6777,216 possible values. If you think visually, consider a 16 bit color monitor vs a 24 bit color monitor. The 24 bit monitor will be able to display much finer color gradations and be less blocky. The audio version is that the sound will have finer detail. And it will be at ALL frequencies, more importantly, the ones us old people can actually hear. This to us is the best argument that can be made for Hi res files that we can see… or hear. At least mathematically.
Does it Matter?
Only you can be the judge of that. It really depends on the style of music you listen to. Is there subtlety in the frequencies that you can hear or is it just loud? Do you want to pay the higher price for hi res audio? Do you have enough storage for the files? Can your equipment play the music? Are you listening on good equipment, especially speakers? By the way, good equipment doesn’t have to cost an arm and a leg. But it will cost more than a few hundred dollars. What environment are you listening in?
To some there is no other way to enjoy music. To others it doesn’t even matter. To us, it's in the middle. Sometimes it doesn’t matter but on Friday night with a good bourbon it can be magical.
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