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Audio
Sound travels in the form of sound waves, and every sound that is transmitted begins and ends its life as a wave. The original sound recording and storage equipment was analog, meaning it stored audio information in a continuous wave-like manner. As technology progressed however, analog formats gave way to digital ones. The most visible example of this transformation was from records and tapes to CDs. Digital audio recordings store a representation of a sound wave in a form that can read and processed by a computer. Digital audio can be easily manipulated in a myriad of ways, it can be duplicated flawlessly, it can be compressed efficiently, it can be encrypted, and it can be easily transported over a network. For these and many other reasons, digital audio has dramatically changed the audio landscape.
Text-based Tutorial
Video Tutorials
Tutorial
Before the workshop, please prepare a short script that includes the following biographical information:
- Full name and college affiliation
- Current name of the course you are taking
- Year you plan on graduating
- One or two hobbies or other interests
Example script: My name is _______ and I'm in Liberal Arts. I am taking STS 331. I hope to graduate in the Fall of 2006. I enjoy surfing and yodeling.
Recording exercise:
Configuring the USB headset microphone
Before we launch Soundtrack Pro, it is important to select your input device. We will be using a Logitech USB headset for these exercises. Do not start Soundtrack Pro until the headset is set up.
First, open System Preferences, select the Sound Control Panel icon. Under Input, select Logitech USB Headset. To adjust the input level, move the slider. In this example, it's at about 75%.
Next, select the Output tab and again choose the Logitech USB Headset.
Now, launch Soundtrack Pro
You will use your headset microphone to record your prepared script two or three times.
Creating a New File
In Soundtrack Pro, create a new audio file that is mono, 16-bit, 48.000 khz.
Next, set your audio input source in the Soundtrack Pro preferences.
Select your input device under Soundtrack Pro>Preferences>Recording.
In the top left corner, select the Recording window and make sure the Logitech USB Headset is selected from the pull down menu. Leave the Monitor device set to None.
Recording
You are now ready to record! Press the red record button at the bottom of the screen to start recording. Be sure to use complete sentences while recording your script. It makes editing so much easier! If you stumble during recording, do not stop: just pause momentarily and then continue from the beginning of the sentence before the stumble. After you have finished recording, press the spacebar to stop recording. Save the audio file.
Editing exercise
Before we begin the editing exercise, it's always a good idea to make a backup copy of your source audio file to use for editing. Select Save As and give your file a new name to indicate it is a backup copy.
Now that your file has been backed up, it's time to edit. We will edit a different version of your audio track for this exercise. Other than your name and college, create a version that will have your biographical information edited together in a different order. You can choose audio from different takes if you recorded your script more than once, so pick the takes that you prefer the most. When you create new files, be sure to make them the same mono 16-bit, 48.000 khz. You will use the selection tool to highlight the portions of the audio you want to copy and then paste them together in a different order. It is also helpful to “insert silence” and to “add markers” to help identify the different sections of audio in the timeline. You can add markers by pressing the “m” key and a marker will be placed at the playhead location. Double-clicking between markers will select the entire section of the waveform between those two markers.
Soundtrack Pro Waveform Editor with selection highlighted
Edited Version: For this example, include the items recorded from your script in this order: name and college, educational background, the subject you teach, and the number of years or semesters you've been teaching.
After editing be sure to save your file.
After editing is complete, choose Save As, then select .aif, 16-bit, 48kHz from the pull down menus. Then click Save.
Effects and filters exercise
For this exercise you will use the new audio file created in the recording and editing exercise. For this example, we will apply the normalization filter, which will make the overall level of the audio consistent throughout the file. First, select all of the audio waveform. Next, choose Effect>Normalization. Be sure to save the audio file after normalizing.
Select the entire waveform then choose Normalize from the process menu
After normalizing, the levels throughout the entire audio file are now more consistent.
Exporting or conversion exercise
For this exercise, we will open the .aif audio file in iTunes and convert it to an .mp3 file.
First drag your .aif file into iTunes.
MP3 exporting must be set up in the iTunes preferences under Advanced>Importing>Import using the MP3 encoder, with the setting Good Quality (128kbps) or Higher Quality (160kbps).
Once the MP3 importing preferences are set up, you will select Convert Selection to MP3.
The MP3 file will be smaller in size than the original .aif file.
iTunes will instantly convert the .aif file to an .mp3 file, and it will show up in the library. The mp3 file can then be dragged to the desktop.
