Hear a recording Alexander Graham Bell made in 1885

The National Museum of American History has released a totally cool reconstruction of an 1885 recording of Alexander Graham Bell reading his handwritten notes.

This video shows the notes scrolling slowly as Bell reads. (Be patient -- the very first part is hard to understand).



The noninvasive optical technique used to scan and recover the recording was invented at Lawrence Berkeley National Laboratory in 2002 with assistance from the Library of Congress. They have used it to reconstruct even older recordings than this one.

I love this sort of thing because it illustrates how we are able to start with very crude proof-of-concept prototypes and refine them over time. There are tons of examples in and out of IT, for example, the Wright brother’s first plane, early automobiles and Doug Engelbart demonstrating WYSIWG word processing, windows, the mouse and many other things at The Demo in 1968.

Doug Engelbart, The Demo

Can you hear the difference when audio is compressed?

We have seen that images can often be compressed significantly without noticeable degradation.

A recent review asks whether one can distinguish between a file that is ripped from a CD with no loss and a compressed MP3 version of the same file.

There were only seven subjects in this small test. They were given two recordings of two rock songs and asked to tell which sounded best. One was a lossless recording ripped from a CD, the other the same file compressed. Some compared the lossless files to 192 kbps MP3s, others compared them to 320 kbps MP3s. (Apple iTunes music is 128 kbps).

Only one person could accurately pinpoint which tracks were MP3 in every case. Of the rest, three subjects picked the lossless track twice and the other three only made one correct choice.

This is obviously a limited test -- there were few subjects and few controls. The results might be affected by things like

• the quality of the playback equipment
• the hearing acuity of the subjects
• the familiarity of the music to the subjects
• the nature of the particular song or other audio

Still, a test like this makes one wonder whether bandwidth is wasted by a lossless file.

You could easily create a similar test and try it on your friends (and yourself).

It would also be interesting to do a test of recorded voice. Podcasts are typically delivered as 64 or 128 kbps MP3 files -- can listeners tell the difference? Would a higher data rate matter?

As storage cost falls and bandwidth increases, how is the audio compression tradeoff of file size versus quality affected?

Two cool audio processing demos

We begin our discussion of audio processing with examples of speech recognition and synthesis.

I've just added two examples you might want to play around with. The first is a voice synthesis demonstration that combines text-to-speech with avatar facial animation. The second is Google's yellow page application, Goog411, which can look up a business phone number and place a call, display a map or send text information. (Goog411 is designed for mobile or desktop use).

Try the speech synthesizer. Can you understand it if someone else enters the text? Does the pronunciation change if you end a sentence with a question mark? An explanation point?

Try Goog411 and see if it can find California State University in Carson, California. Does it work well if you have an accent? For a man or woman? When there is ambient noise?

A terrific how-to on recording broadcast quality telephone interviews with Skype

We cover audio processing, and Doug Kaye and Paul Figgiani have put together a terrific 22.5 minute presentation on recording interviews using Skype. You no longer need expensive equipment to make broadcast quality recordings of phone calls. A Mac or PC running Skype, a USB head set, a low-cost audio capture program, and this presentation are all you need. (Even if you are not recording telephone interviews, much of what they say applies to audio recording and processing in general).

For discussion of the presentation and more on audio recording and editing, see Kaye's Conversations Network forums.

Are there people you would be interested in interviewing?

Soundsnap -- free sound effects and loops

I've added a link to Soundsnap.com to our class notes on audio processing. Soundsnap, a growing library of free, user-contributed sound effects and loops, was established by 25 year old Tasos Frantzolas, a Greek sound designer.

Go to Soundsnap for the barking dog, meowing cat or explosion you need for your podcast, and, while you are at it, how about contributing a sound effect of your own to the collection?