E-learning Curve Blog at Edublogs

The first principle of digital audio is:

Digital audio is the study of discrete values.

This allows us to manage audio information very efficiently. Using digital techniques, the capability to process information is greatly enhanced.

In a previous post, I discussed a little about the basics of digital audio. Today, I want to talk about how digital audio technology benefits podcasters. What are its advantages over an analog system of recording?

Here are a few specifics:

1. Less noise than an analog recording system.
   In an analog recording system, magnetic particles are oriented by the tape head in a manner that is analogous with the audio signal that is driving the tape head. The tape itself has billions of little magnets on it, and it is physically impossible to orient every single one correctly. These remaining magnetic particles are randomly oriented, which shows up on playback as what is called tape hiss. With a high enough sample rate and resolution, digital audio produces recordings that have significantly less noise than analog.

   The noise in an analog recording system is usually expressed as a “signal to noise ratio”. The signal to noise ratio tells you how much more signal there is on the tape recorder outputs compared to the noise in a audio signal. For example, a digital audio system using a resolution of 16 bits will often yield a signal to noise ratio of more than -90dB (in EMG’s in-house studio the noise threshold is, for example) for decibel, a unit of measurement in the audio world. -90dB means that the noise floor is 90dB below the signal level.

   It would take a very high-end and expensive analog recording system to produce even a signal to noise ratio of -60db. This difference of 30dB is dramatic: the noise floor in the analog recording system will be 1000 times louder than the noise floor in a digital system. The reason for this is quite simple: a digital recording system records only the binary numbers, not analog signals which accumulate noise from the imperfect recording process. Since a digital system only records numbers (zeroes and ones, or bits, to be specific), as long as the bits can be recorded and read by the digital tape or digital disk system, then the only thing that matters is the theoretical 6dB per bit of dynamic range that is determined by the resolution of the digital recording system.

2. Ability to make copies without signal loss.
   Another advantage of digital audio over analog is the ability to make as many copies of the original as you want without degrading the signal quality. Every time you duplicate an analog recording, you lose audio quality and add even more noise. Remember that digital audio is just a group of digital samples, made up of zeros and ones that represent the audio.These numbers can be “copied” to another device or medium in a way that ensures that the result is the same as the original. This means that the copy is a “clone” of the original and sounds the same. This is true for the first copy or the seventy-first. Each time you copy an analog recording, you introduce between 3 and 6dB of noise, which further reduces the signal to noise ratio. Clearly, for pristine back-up want to use multiple copies of material during production, digital has the advantage.
3. Better audio quality for a lower cost.
   Digital audio used to be much more expensive than analog. This was because the early digital tape recorders used expensive and precise reel-to-reel mechanisms and early digital technology which was inherently more expensive. As recently as five years ago, the cheapest digital multi-track on the market was over $10,000 – analog reel-to-reel machines could be had for a fraction of that price. Now, digital technology has advanced to the point that this is no longer true.This is much in part to the advancements made in digital technology due to computers as well as cost reduction of other technologies important to digital recording like video cassette mechanisms and hard disk drives. Since digital audio technology uses similar components as the computer and multimedia industries, digital audio devices can take advantage of the lower cost of components due to their high manufacturing volumes. The result? Today’s digital audio multi-tracks not only out-perform analog machines, costs less to manufacture, and is quite easily integrated into a multimedia production environment.

More…

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New E-Learning Curve’s Other Podcast episode release:

Part 7 of Transatlantic: The Flying Boats of Foynes

In Part 7: End of an Era

The War in Europe ended on May 25th, 1945. As normal life re-established itself, times also began to change for Foynes. Larger and more powerful airplanes had been built and operated successfully. A new land-based airport was established at the far side of the river. It was called Shannon International.

In this final episode of Transatlantic: The Flying Boats of Foynes, Chief Operator of Launch Operations Frank Buckley describes the end of the flying boat service in Foynes, Ireland, and the emergence of Shannon airport as the new home for transatlantic aircraft in the Post-War years.

Click here to listen to the podcast (MP3, 8.5MB).

Click here to view the transcript of this podcast (PDF, 24K).

Even though this is an e-learning blog, the observant among you will notice that the podcast isn’t about e-learning. That’s OK – the point of e-learning is to provide training professionals with a means of creating and distributing content that enables people to acquire information, knowledge, skills, and expertise on a diverse range of subjects: as e-learning practitioners, it’s our job to facilitate this process.

My previous blog posts on podcasting have focused the human side of podcasting: narration, story-telling, communicating with your audience. I’ve looked at what you say, and how you say it, dipping liberally into the eighty or so years of accumulated skills and knowledge from radio broadcasting to reinforce my arguments – after all, content is king, and radio is still the place where people talk.

Now, it’s time to spend a little time understanding the technical aspects of podcasting. Don’t worry if you’ve never so much as looked at a sound file before. Recording and producing your own content is great fun, and I hope you’ll find that there’s tremendous satisfaction to be had creating and crafting your own little corner of the internet.

As you begin to hone your podcasting skills, you’ll find that you’re also taking a remarkable learning journey. It’s one that I think will enhance the way to sense and think about the medium of sound. If you are a musician, you’ll already know what I mean. Those of you who can play (even if it’s only a few chords on the guitar) know that you listen to music in a qualitatively different way to those don’t play. The very act of learning an instrument teaches you to become an active listener and a critical analyst of sound. How is that musical piece orchestrated? How are the harmonies arranged, what technique is that soloist using? What melodic elements hold your attention? As well as just enjoying a musical number on its own merits, you can apply a critical ear to the music, and I would suggest appreciate a work in a much more profound way than the casual listener. The same principles apply when you begin to podcast.

Jack Herrington (2005) agrees with this interpretation. In his text Podcasting hacks: tips & tools for blogging out loud, he considers that there are four elements you should critically examine:

Podcast Structure: Analyze content for recurring or format elements used to keep the listener engaged with the podcast, and to motivate the listener to return for future elements. Is the “interesting stuff” (p.51) at the beginning, the middle, the conclusion, or distributed throughout the pod cast presentation.

Technical Elements: Podcast should take advantage of appropriate Web 2.0 and multimedia components to be effective. In some instances, this can mean a voice-over narrating a story very simply. In other contexts, a podcast may take advantage of music, wildtrack, multiple voices, and sound effects.

Content: Try to understand what holds your attention. This is especially vital: according to Herrington, it’s what “primarily keeps people coming back” to listen again. The author suggests that

“When something moves you, listen to it over and over to figure out what is keeping you engaged.”

(p.52)

Next time: Fundamentals of Digital Audio Editing

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New E-Learning Curve’s Other Podcast episode release:

In Part 6: The Flying Boats at War

During World War II, the civilian airlines of the Allies continued to fly, though perhaps the nature of the passengers had changed. As the US, Britain, and their allies prepared for the invasion of Europe,

In this episode, Chief Operator of Launch Operations Frank Buckley describes working on the flying boats during the War, the hazards that the aircraft encountered, searching for the German battleship Bismarck, and the excitement of the night-time take-offs and landings.

Click here to listen to the podcast (MP3, 11MB).

Click here to view the transcript of this podcast (PDF, 24K).

Even though this is an e-learning blog, the observant among you will notice that the podcast isn’t about e-learning. That’s OK – the point of e-learning is to provide training professionals with a means of creating and distributing content that enables people to acquire information, knowledge, skills, and expertise on a diverse range of subjects: as e-learning practitioners, it’s our job to facilitate this process.

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References:

Herrington, J. D. (2005). Podcasting hacks: tips & tools for blogging out loud. O’Reilly Media, Inc.

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