Digital AudioDigital Audioand usingand usingAudacity

SoftwareSoftware

Michael Nieckoski

Technology Learning Services

November 2008

Agenda

What is Digital Audio?– digital vs. analog– digitizing analog materials

How do I make digital audio files?

Using Audacity software

How can I use audio in my teaching?

afnbroadcaster.blogspot.com

Analog Media

Analog Computer

Media

Difference: Analog/Digital

Analog systems use a continuous and constantly varying range of values to represent information.

Digital systems use discrete (discontinuous) values, usually but not always symbolized numerically ("digits") to represent information for input, processing, transmission, storage, etc.

Analog Representaion

Digital Representaion

Sampling

Sampling is the act of cutting an analog signal into pieces, then attaching a numerical value to each piece. These “digits” are put in a table and into a file on the computer.The sampling rate defines the number of samples per second taken from a continuous signal to make a discrete signal (analog-to-digital conversion).

Audio Digitizing

SamplingMeasured in hertz (Hz) – cycles per second.CD audio files have a sampling rate of 44.1 k. CD audio is like a movie for your ears with 44,100 frames per second flashing across the screen.The more detailed you want the sound, the more samples you need.The inverse of the sampling frequency is the sampling period or sampling interval, which is the time between samples. (The holes in the sound).

Samples per second8000 Telephony standard.11025 a quarter of the CD sampling rate, or half the Mac16000 Used by the G.722 compression standard.18.9 k CD-ROM standard.22050 half the CD sampling rate (used to make smaller files)

32000 Used in digital radio, TV work, also long play DAT and Japanese HDTV.37.8 k CD-ROM standard for higher quality.44100 The CD sampling rate.48000 The DAT (Digital Audio Tape) sampling rate.96000 Professional Studio Recording Software

Pop Quiz (analog/digital)?

Which system gives a truer representation of a sound?

AnalogAnalogWhich system can give a clearer representation of the sound?

DigitalDigitalIf you want a higher quality sound recording, what must you do when you digitize?

Use a Higher Sampling RateUse a Higher Sampling Rate

What is Audacity?

Freeware

Audio Recording/editing software (originally designed for musicians)

Saves digital audio files in various formats– MP3, WAV– Can export as multiple files (multi-track)– Saves “projects” and finished files

Using Audio in your Teaching

Feedback to Students on papers/projectsRecording a class (or portion)Accept audio from students instead of written material Advanced organizers for class meetingsReading to your students (ex. Poetry)In preparation for blended/online learningWLMC Radio Station

Promotes Universal Design??

Get Audacity!Go to:– http://audacity.sourceforge.net/

Install the applicationGo to:– http://intranet.landmark.edu/tls– Download the lame.dll plugin– Put it into the Audacity folder on your computer– When exporting to MP3 the first time, choose

this file.

Let’s have a look at it…

Hints and Tips

Learning to “see” sound

Make your files 3-4 minutes

“Always” use MP3 format for final distribution– Smaller files– Ss can download them to MP3 players

Michael NieckoskiManager, Technology Learning Services

Landmark CollegePutney Vermont USA

michaelnieckoski@landmark.edu

Image Digitizing

* During the scanning process, each pixel in the photo is assigned codes for:Color, brightness, contrast, location, etc. The digital codes are placed in a table and saved as a file. •When you display the image, the software decodes the File, reads the coded values, and paints it to the screen.