Sound Basics and SoundEdit 16 Review Notes Sound Basics Sound On a Macintosh SoundEdit 16 Review Sound Basics A sound can be represented as a waveform. The height of the waveform represents the amplitude. Amplitude indicates the loudness of a sound. The distance between the peaks is called a cycle. The number of cycles that occur in one second is called the frequency. Frequencies are measured in Hertz or Kilohertz (Hertz is 1 cycle per second, Kilohertz (kHz) is 1,000 cycles per second). In order to reproduce the sound accurately you must capture enough points along the sound's shape. The number of points (per second) you use to capture the shape of the sound is called the sampling rate. The minimum rate for sampling must be twice the frequency of the sound. So, a 44 Kilohertz sampling rate takes twice as many sample points as a 22 Kilohertz sampling rate. Analog data is converted to a digital approximation. This digital data is then converted back to a close approximation of its original analog data. (Take a look at The Multimedia Library's Analog and Digital to understand these terms better.) The higher the sampling rate, the closer the digital approximation. Sound On a Macintosh Pull down the Apple Menu. Select Control Panels and choose the Sound Control Panel. Click and hold the box which says Alert Sounds. This brings up a box which lets you select Sound In and Sound Out sources and Volumes (for the internal speaker and for headphones). To set up your Macintosh for recording, select Sound In. Once Sound In has been selected an Options button will appear. Click on this button, which brings up the following dialog box. To set your input source, that is, the device from which you will be recording sound, click the radio button below the icon which matches your input source. Click Microphone if you will be speaking into the microphone plugged into the back panel of your Macintosh. Click AV Connector if you have an AudioVisual monitor with a built-in speaker, or click Internal CD if you will be recording from an audio CD in the built-in CD-ROM drive of a Macintosh AV system. Check Play-Through to hear the audio from any of these sources through the internal Macintosh speaker. Sound Out lets you set the rate and resolution of the Macintosh sound output. Volumes lets you set the sound level coming out of the built-in speaker and the built-in Macintosh headphones. SoundEdit 16 Review SoundEdit 16 is software used for editing, enhancing, playing, analyzing, and recording sounds on any Macintosh. The program allows you to record, edit, and play multiple 8- or 16-bit soundtracks in a variety of formats (see below). Using effects such as echo, reverb, normalize, and pitch shift, you can alter the tracks to your liking. Each track contains separate level and pan controls for changing the volume of the sound as well as its position in the stereo field (left, right, or middle only). These separate tracks can be combined into a single track or stereo pair with the Mix command (see below). In Version 2.0, the volume and panning of a mixed track can be changed over time. SoundEdit 16 can save files in the following formats: SoundEdit 16 can handle multiple simultaneous sound tracks, and mix them together digitally, to create a mono or stereo result. In SoundEdit 16 sound is represented graphically in a condensed waveform format. Selections are made by dragging the mouse over an area of the sound track. When the mouse button is released the selected area is highlighted. To extend a selection, hold down the shift key and drag to indicate any additional selection. When using the zoom controls in SoundEdit 16, you can prevent the redrawing of waveforms dynamically (which can be annoyingly slow) by holding the option key down while dragging these controls. The sound in a track can be moved forward and backward in time by holding down the option key and dragging horizontally. While the option key is held down the cursor changes to a 'scrolling hand'. Double-clicking in the sound format information box in the lower left corner of any SoundEdit 16 file brings up the Sound Format dialog box. Both the Controls Palette and the Selection Palette can be expanded to add additional functions. This is done by clicking on the zoom box found in the right hand corner of each palette. When the Controls Palette is expanded, Effects shortcuts buttons appear. When the Selection Palette is expanded, the horizontal and vertical position of the cursor is shown. Press the record button on the Controls Palette to start recording, or hit Command-R on the keyboard. The sound captured by recording will be inserted into the current sound track, starting at the start of the current selection if one has been made, or at the current cursor position if the track has been clicked. (Otherwise it will be inserted at the beginning of the track.) During recording, a gray progress indicator bar displaying the actual record time and the maximum available record time appears in the expanded Controls Palette. The Play button on the Controls Palette starts a selection playing. Pressing the space bar also starts and stops playback, as do the keyboard Command-P and Command-period. If a part of the track has been selected when play starts, only the selected portion of the track will be played. (The area in black is the selected area.) To add a track to an existing file, use the Add Track command in the Sound menu. To record in any of these tracks, click in a track to set the starting time for the recording, and then record just as for a single track. Sound can be selected in any of these tracks by dragging, and then copied and pasted between tracks, either within a single file or between separate sound files. To play one track of a sound file containing multiple tracks, click in the desired track and press the Play button. To play all tracks simultaneously, click in any track, hold the shift key down, and press the play button or the spacebar. Play will start from the point clicked. (This is referred to in SoundEdit 16 as the insertion point.) Under the Sound menu, the Mix command forms a combination of all the tracks of the currently open file. The mix created can be either mono (one-track) or stereo (two-track). Set Loopback is used to define the current selection as a portion of sound which is to be played repeatedly. Loopbacks can be used to increase the duration of a sound without increasing its file size. Set Loopback is only available when a selection has been made. Use the option key to play a sound with loopback enabled. The Fade Out effect under the Effects pull-down menu gradually decreases the amplitude (volume) of a sound over its duration.