Sound In/Out

You can connect a microphone, VCR, tape deck, or audio CD player to a Macintosh and send the sound signal from the device into the computer, where the audio can be recorded and manipulated digitally. As with all audio equipment, the audio level or impedance specification should be followed.

All Macintosh computers have built-in speakers. You may also attach amplified speakers or headphones. Most current and in-warranty Macintosh desktops and portables have sound input and output jacks (shown in the following figure, left and right, respectively), but some models do not include a microphone or external speakers.

The sound input and output ports use stereo miniplug style connectors, similar to those on portable stereos and headphones. Below you see an audio cable with miniplug connectors on both ends (top) and one with a miniplug connector on one end and two RCA-type connectors on the other (bottom).

The computer's audio input and output capabilities feature 16-bit stereo sound with 44.1 kHz and 22 kHz sampling rates.

Most of the recent Macintosh computers with built-in displays come with a tiny built-in microphone that resembles a small hole in the display bezel. This microphone can be used in conjunction with features of the Mac OS for recording external sounds and responding to spoken commands. However, for better sound quality and recognition, you need to connect an external microphone.

To use a sound input device other than the built-in microphone, select the appropriate input source in Sound preferences. This is also where you configure the computer's recording and playback functions.

Optical Audio

The Power Mac G5 and iMac G5 feature a set of audio capabilities not commonly found before in personal computers. This includes optical digital audio in and out ports. These use the Sony/Philips Digital Interface (S/PDIF) protocol over optical cables for connecting to devices such as decks, receivers, digital instruments, and even 5.1 surround-sound speaker systems.

Since optical digital audio transmits data as impulses of light rather than electrical signals, it enables true noise-free, pristine sound, eliminating troublesome ground loops.