Intro

A movie generally has a few “layers” of audio. There is the audio that the camera records which includes dialog, background sounds, etc. Then there is a musical soundtrack. Lastly there is sound “effects” - sounds that are created in the studio to enhance the audio experience.

Thinking about soundtracks for a moment…

Think of a soundtrack from a particular scene of movie that is such a memorable part of that scene that without it the scene would not have been the same.

Now think about exchanging that soundtrack with one of the exact opposite type. What happens?

Ask me for some of my examples.

Oh… did you know that the sound of the “birds” in the Alfred Hitchock movie weren’t actual birds?

The bird sounds were created on a synthesizer. Why? Because the surreal sound of the synthesizer birds was stranger (creepier?) than using real birds.

A Simple Experiment:

Let’s start with a movie clip of a girl going home and see how music can alter the mood.
Here’s a still:

I wonder what’s going to happen… let’s add some music and see!
Maybe… she is going to a party? (click below to play or if you cannot play Flash Video click here for a Quicktime version):

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Then again… maybe there’s danger ahead? (click below to play or if you cannot play Flash Video click here for a Quicktime version):
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Same footage but with two different soundtracks - giving a very different feeling. This is a fun experiment that you may want your students to do as well.

Below we review some of the main areas of Audio production without details of implementation with specific software. After that we will do some hands on work with a software application for audio. Note that some video editing applications have very sophisticated multi track audio applications built in. Others are very minimal.

Digital Audio Production and Demo (Audacity)

Audio production including field recordings, live and studio recordings has been around for quite some time. For many years audio production was done using multi-track tape machines and a room full of studio equipment for processing the audio - echo, reverb, equalization, etc., all of these being hardware that the audio signal would pass through. Today we can accomplish the same thing on an average home computer that once took a room of specialized equipment.

Let’s take a look at audio input in the three major stages of input (or capture), processing and output.

Input

Input is the audio signals, the sounds themselves. This generally comes from a microphone or from importing a file containing a digital sound. If you are recording with a microphone, use your computer’s sound input (Control Panel on Windows, Audio/MIDI on a Mac) to make sure that sound is coming in and that the level is good. The level is often shown by a meter and can be further adjusted within your audio software. After you start up your audio software, make a short test recording to verify that the input level is good. You don’t want it too low because it will sound noisy when you adjust it and you don’t want it too loud or you will get distortion. Distortion is when the audio sounds “dirty” or “fuzzy” because it was recorded too loud - think of when someone is yelling into a microphone and you can’t figure out what they are saying. Amplitude is another word for volume or level and is often used in audio production. To import a sound from a digital file, you will use your software’s import function. In either case the software will show you a waveform display of the sound over time. This is called the timeline.

Processing

This is where you can have a lot of fun and of course really fine tune your work. In your software you will find the processing units under “effects”. Some software has literally hundreds of effects. In case you have heard rumors that software can be used to make someone’s voice sing on key (when they are really off), it’s true! You can do that. Although there are hundreds of effects, we will concentrate on a few that are really essential:

• Amplify (or Amplitude Adjustment) - this will make your audio track louder or softer.
• Change Pitch (or Change Speed) - You can change the pitch (frequency) to make someone’s voice sound higher or lower without changing the speed of the recording or vice versa.
• Compression - generally a compressor/limiter combination is used to limit the range in volume of a recording. This means that things that were very quiet are a bit louder and things that were very loud are a bit quieter. This is used heavily in radio where they want the signal to stay about the same.
• Equalizer - An equalizer allows you to adjust the volume around certain frequencies. You know how a stereo system will have bass and treble? Well instead of that think of having bass, midrange and treble. Now think about adding more so you have 8 levels to adjust, or 16, or 32!
• Fade (in/out) - Fading in or out is a technique of making the signal gradually change - getting louder or softer. You’ve heard this a thousand times at the end of a song.
• Normalization - this is used to raise the overall volume to a certain level - e.g. to “0″ but is done in away so that it doesn’t distort the signal. So when you want the sound to be as loud as possible without worry, use Normalization.

Output

Once you have all of your tracks recorded and the processing finished, you are ready to make this into a file that other people can hear. This might happen as part of the “mixing” process but generally, you will do all of the set up and simply click as Export (or Render) to save the final mix. There are various formats and we will discuss them more later but for now here’s a few of the most common:

• WAV - Microsoft’s audio format (but will play on just about everything)
• AIFF - SGI/Apple file format (will also play on just about everything)
• MP3 - a “compressed” file format (MUCH smaller that the other two) which will play on computers and other devices that support mp3s.

Activity

Audacity is a free, open source, cross platform audio program that can be used for creating soundtracks, podcasts, etc. You can download it here.
Using Audacity, have students work in groups and create a short (1 to 2 minute) audio PSA. You should have at least two tracks - one with a voice and another with music or sound effects.