The iMac has three different sound-in sources:
- the built-in microphone
- the microphone jack
- the CD-ROM drive
Audio output can be provided by three different methods:
- internal stereo speakers
- headphones or external speakers in the headphone jacks on the front of the iMac
- headphones external speakers connected to the Line output jack in the side panel of the iMac
Line output is a sound-out port that does not amplify the sound. If you compare the line-output port and the headphone port, the line-output port will have lower volume levels.
Recording Sounds - The Equipment Needed
The iMac can use a number of sources to record sound. The table shown below identifies the sound source, microphone compatibility, OS recording capability, and the connection type.
| Sound-in Source | PlainTalk Microphone Compatible? | Omnidirectional Microphone Compatible? | Can OS Record From? | Connection Type |
| Built-In Microphone | Yes | No | Yes | Built-In |
| External Microphone | Yes | No | Yes | Headphone Plug |
| CD-ROM Audio | No | No | Yes | CD Audio Cable |
CD-ROM Audio is the analog audio signal that is provided by CD audio disks, NOT sounds that may be part of CD-ROM titles.
The side microphone jack can use either a third-party microphone or an Apple PlainTalk microphone. There is a difference between a PlainTalk microphone and third-party microphones. PlainTalk microphones are amplified by the computer. They receive power for amplification from an 1/8 inch plug extension that makes contact with specific connections in the microphone port. That's why the plug on the PlainTalk microphone is longer than other external computer microphones. Remember that both types of plugs may be used in the side microphone jack.
The iMac has the ability to record sounds within a bandwidth of 44.100 KHz; it will not record sounds at 11 or 22 KHz bandwidths.
Note: iMac will support Apple Speech Recognition with version 1.5.4 of the English Speech Recognition software available from the Apple Software Updates web site at
http://www.apple.com/swupdates.
Sound-Out
Source | Amplified
Signal? | Analog or
Digital | Built-in Speakers Muted When Using... | Muted with Headphones? | Uses SRS? | Connection
Type |
| Built-in Speakers | Yes | Analog | n/a | Yes | Yes | Internal Connection |
| Line-out Jack | No | Analog | yes | Yes | Yes | Headphone Plug |
| Headphone Jacks | Yes | Analog | yes | No | Yes | Headphone Plug |
The Monitors and Sound control panel lets you select the source that you want to record from. The control panel displays the current recording quality, output port, and whether or not SRS 3D stereo sound is active. As shown above, SRS 3D sound works with any of the output sources.