This chapter includes the following sections:
The Audio Panel lets you adjust the audio parameters—such as the volume and sampling rates—of audio coming into your system. Use it to set up and control microphones, CD players, and other audio devices connected to your workstation. Open the Audio Panel by clicking the words Audio Panel . Once you set the workstation to record or playback audio, use other media tools, such as Sound Editor and Capture, to record audio for use in movies or online presentations. Click the words Sound Editor and Capture to open those applications.
The Audio Panel is installed automatically if you have audio capabilities on your workstation. The Audio Panel is shown in Figure 2-1.
Use the commands available from the Menu Bar to adjust the audio parameters. These sections describe how to use the different commands in the Menu Bar:
Use the Rates menu to control the input and output sampling rates.
| Input Rate | Choose the sampling rate for audio you are recording. Choose the same sampling rate as that of the source media. If you are recording from digital media, the input sampling rate is set automatically to the rate of the incoming digital data. | |
| Output Rate | Choose the sampling rate for audio you are recording. |
See “Selecting a Sampling Rate” for more information on how to choose the appropriate sampling rate for audio recordings.
The Speaker sliders marked L and R control the volume of the left and right output channels. The resulting sound is sent out through the single built-in speaker.
If you have headphones connected to the headphone jack, the left and right sliders control the left and right headphone levels. Adjust the Speaker levels to control the speaker and headphone volume.
The Audio Panel is set so that a single slider adjusts the right and left input levels simultaneously. You can separate the sliders so that you can adjust the left and right levels independently. Select the Options menu and choose “Input Sliders Independent.”
A single slider also adjusts the right and left speaker levels simultaneously. You can separate the sliders so you can adjust the left and right levels independently. Select the Options menu and choose “Output Sliders Independent”.
The microphone that ships standard with Indy and Indigo workstations is a monophonic microphone. If you have a stereo microphone hooked up, select the Options menu and choose “Stereo Microphone.” The Audio Panel resizes automatically to accommodate the additional input sliders.
If you have an Indigo2 workstation or an Indy workstation, you can switch from stereo mode to four channel mode (when using four independent channels of input and output).
Open the Options menu and choose “Four Channel Mode.” A second pair of Input sliders appear on the Audio Panel. See also the audio(1M) man page for more information on four channel mode.
Use the Input menu to select your audio input source.
 | Note: See your workstation owner's guide for instructions connecting audio devices to your workstation. Alternatively, if your system has a audio option board, see the owner's guide that came with the option board for information on how to connect audio devices to the option board. |
| Microphone | Select “Microphone“if you want to record from a microphone connected to the mic jack on the back of your workstation. | |
| Line | Select “Line” if you want to record from an audio device connected to the line-in jack on the back of your workstation. | |
| Digital | Select “Digital” if you want to record from a digital audio device connected to the digital jack on the back of your workstation. |
When you record from a microphone or a device connected to the line-in jack, the workstation converts the audio signal from analog to digital. To convert the signal into the best possible digital data, adjust the input levels to weaken or amplify the signal, according to the sounds you want to hear.
The input levels affect only those signals that are converted from analog to digital, so adjusting the input sliders won't have any effect on digital input.
Follow these steps to adjust the input levels for hardware connected to the line-in and microphone jacks:
Click the Meter checkbox to display the signal range.
If you are setting the microphone input levels, click the Monitor checkbox to hear the audio as you adjust it.
Audition your audio.
If you are recording from a microphone, utter a test message such as, “I will speak at this level consistently at this distance from the microphone.”
Adjust the Input sliders until the meter displays green and often yellow without reaching into the range of red. See “Separating Ganged Sliders” to separate sliders so you can adjust them independently.
If the meter displays only green, the levels are too low.
If the meter displays any red, the levels are too high.
If the meter displays green into yellow, the levels are correct.
If your recordings contain too much environment noise, move the microphone closer to your mouth and readjust the input levels. If your recordings contain too much breath puff on words that begin with P and B, move the microphone further from your mouth and speak over the microphone, rather than into it.
Click the Monitor checkbox to hear the audio as you speak into the microphone. See “Adjusting the Input Levels,” for more information on how to adjust the input levels to make clear recordings.
Click the Meter checkbox to see the audio range as you speak into the microphone. See “Adjusting the Input Levels,” for more information on how adjust the input levels to make a clear recording.
When an audio signal comes into your workstation, the workstation converts it from analog to digital. The sampling rate determines the rate at which samples are taken from the analog signal and sets the upper limit on the high frequency content of your recording.
Choosing the appropriate sampling rate for the audio you are recording helps prevent distortion in your recording. Telephones use an 8 kHz (kilohertz) sampling rate, which is adequate for voice-quality audio. Compact discs use a 44.1 kHz sampling rate, which is necessary for music-quality sound.
The highest frequency in your recording may be half the sampling rate. For example, the highest frequency in a telephone signal can be 4 kHz because the sampling rate is 8 kHz. Recordings made at an 8 kHz sampling rate will be muffled, while recordings made at a higher sampling rate will be clearer.
Higher sampling rates yield better recordings but require more disk space. For example, a five minute, 16-bit stereo, 44.1 kHz AIFF file requires approximately 53 megabytes of storage. Using audio data compression is a better way to save disk space than recording audio at low sampling rates. Use the Media Convert tool for compression of audio files.
When recording digital input, the sampling rate is determined by the source of the sound. For example, a CD player with a digital output jack sends information at 44.1 kHz. The workstation automatically locks to that rate.
Once you have recorded at a low sampling rate, you cannot recover the original signal. If the quality of your recording is important, record at the same sampling rate as the source media and adjust the sampling rate down incrementally with Sound Editor to save storage space.
If you are monitoring the recording and the sound is distorted, make sure that the input and output sampling rates are the same. Use the default sampling rate if you don't have a preference.
| Note: Sampling rate is a global setting. Changing it affects all other audio processes that are running. |
To adjust the sampling rate:
Select the Rate menu and choose “Output Rate.”
Select the rate that most closely matches the sampling rate of the input.
The input sampling rate is determined by the maker of the media you are recording from.
To see what the input rate is, select the Rate menu and choose “Input Rate” from the menu. The input rate has a blue checkmark in the checkbox.
Desktop sounds are the sounds you hear when you perform certain actions, such as double-clicking an icon or emptying the dumpster. Your system ships with desktop sounds turned on. You can turn off these sounds by using the Desktop Settings control panel. To open the panel, click on the word Desktop .
To turn off the audio feedback:
Click the button next to “Desktop Sounds”.
Click the Close button to close the panel.
Desktop sound stops immediately for some applications. For others, you need to log out and log back in before the sound stops.
Key click is a clicking sound you hear when you type on your keyboard. Your system ships with the key click turned off. You can turn key click on or off using the Keyboard Settings control panel. To open the panel, click the word Keyboard . To turn on the key click:
Click the button next to “Key Click.” A red checkmark appears in the box.
Click the Close button to close the control panel.
The Options menu contains the following commands. Not all options are available on all types of workstations.
| Audio Queue Monitor |
| |
| Input Sliders Independent | ||
| Output Sliders Independent | ||
| Decibel Scale | Changes the Input slider scale to decibels. | |
| Listening LED | Adds an LED that “lights up” when any application other than Audio Panel is using an audio input port. | |
| Four Channel Mode | ||
| Stereo Microphone |
|
The Presenter LCD flat panel display product features additional audio output. A “Presenter Audio” commands appears in the Options menu if you have Presenter installed on your workstation.
The dual output sliders are collectively ganged with the primary Audio Panel output sliders. The Tone command adjusts the brightness of the sound.