Yearly Archives: 2013

Audio Quality: Sample Rates, Bit-Depth, Human Physiology & The Golden Ears

studera800.jpgThere is a curious interface between science and the senses. Perception is often wrapped in psychological or emotional elements. This comes in many forms. It can be a group trying to share their impression of the taste of a particular wine. It can be people listening to music. Every persons experience of such things, being filtered by all that is us, both physically and mentally, is unique.

In a recent post I referred to a silly trend in very high sample rate music. This has been promoted by a variety of people, including HD Tracks, a music reseller that promises to provide “audiophile grade high-resolution recordings.” This term they use to generally describe digital recording a structure beyond the 44.1 KHz sampling and 16 bit linear word length defined by the CD format. They offer music at up to 24 bits and 192 KHz sample rate.

I’ve come to regard this trend as having very little merit. I came to this conclusion after many years dealing with digital audio production, after some experimentation and a lot of research. Like everything else on this site, I don’t profess to be any kind of expert, but I am happy to share my experience.

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Audio Sample Rates: Terminology vs Application

I’ve recently started to develop a grumpy streak with respect to the use of certain terminology with respect to telephony. Maybe telephony isn’t exactly the right word, let’s say that my unease arises from some odd terms surrounding audio quality in the context of communication. I think that some of the language needs to be more application sensitive.

A few years ago the world was a simpler place. The “Plain Old Telephone System” (aka POTS) was definitely a narrowband medium. Where “narrowband” implied digital sampling at 8 KHz and a useful audio channel of 300 Hz – 3,400 Hz.

Some people using more advanced systems enjoyed “wideband” audio. Wideband in that case was defined as a 16 KHz sampling yielding a useful audio channel of 50 Hz – 7 KHz. The TIA-920 standard, which I have referenced previously, spells this out. A variety of audio codecs can deliver this capability including; AMR-WB, EVRC-WB, G.722, G.722.1, CELT & Opus.

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A Gigaset With A Blacklist & The FTC’s Robocall Challenge

Gigaset-C620AEarlier this week I saw a press release detailing a new model of Gigaset cordless DECT phone. This new model, known as the Gigaset C620A, isn’t even SIP capable so normally I wouldn’t give it the time of day. However, the release placed unusual emphasis on one particular feature…a blacklist function intended to reduce the impact of nuisance calls.

Nuisance calls have been on my mind lately, not so much because we get them…because we generally don’t suffer such a problem. They’ve been on my mind because ZipDX’s David Frankel has been railing against the outcome of the FTC/FCC sponsored Robocall Challenge intended to crowd source a solution to the problem of such calls.

David entered that contest but was not one of the winners. He made some inquires about the judging criteria and scores, but met with resistance. In fact, David’s experience following up on the scoring was pretty bad. So much so that he’s been pursuing the FTC and FCC for more details. His efforts in this pursuit made it into The Wall Street Journal on June 25th.

While the contest was over some time ago, there was a Senate hearing on the subject just last week.

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An Interesting History Of Headphones

k240studioSome time ago I stumbled upon a nice article that proposed to be something of a history of headphones. It’s a fairly good effort on the part of the author. However, I would like to add my two-cents in reference to a couple of missing items that I think are significant.

When I was in school in the mid-1980’s I was studying music recording and broadcasting. I spent a lot of time in and around various recording studios around Toronto. The single most common headset that I saw at that time was the AKG K240 Studio monitors. These were the reference grade dynamic headphones used in many facilities at that time.

The K240s are genuinely, big-ole, cans. A circumaural headphone with a semi-open design they sound great, even today. They can be cleanly driven to excessive volumes if required. Fairly efficient, they can even be powered by a cell phone or iPod.

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Sightdeck: High-End Compositing & Virtual Sets Meet Telepresence

SightDeck_AdMore and more it seems that things from long in my past are recurring in the present day. To give you some context, you should know that in the early ‘90s when I was working as an editor in video post-production I became very familiar with blue/green screen techniques.

At one point I was editing commercials for a large Canadian supermarket chain where the President was blue screen composited against close-up shots of the products. We made tremendous use of Ultimatte gear as well as Ampex’s Spectrakey.

Jump twenty years into the future when this I see that Telepresence Options is highlighting Sightdeck, a live presentation facility for telepresence applications. Sightdeck is from iMatte, a company created by the founders of Ultimatte. Warning, iMatte’s web site is a study in lame.

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