The 16-bit stereo audio circuitry provides sound input through the built-in microphone and the USB port and sound output through the built-in stereo speakers and the A/V jack.
All audio is handled digitally inside the computer, including audio data from the DVD-ROM/CD-RW Combo drive, the modem, and devices connected to the USB and FireWire ports. Sound data is converted to analog form only for output to the internal speakers and the A/V jack.
The sound circuitry handles audio data as 44.1 kHz 16-bit samples. If audio data sampled at a lower rate on another computer is played as output, the Sound Manager transparently upsamples the data to 44.1 kHz prior to sending the audio data to the Tumbler sound circuitry.
The A/V jack is located on the left side of the computer at the left palm rest. The jack accepts either a stereo mini-plug or a special plug that has an additional contact ring that carries the composite video output signal. See also "Composite Video Output".
The stereo audio signals at the jack are configured to drive a pair of low-impedance stereo headphones. External powered speakers may also be connected to the A/V jack.
The audio signals on the A/V jack have the following electrical characteristics:
The computer has a built-in microphone located at the upper right hand corner of the display.
The computer has a stereo pair of speakers located between the keyboard and the display. The Tumbler sound system provides parametric equalization for the speakers. The computer turns off the sound signal to the speakers when headphones are connected to the A/V jack.
The Pangea IC receives call progress audio from the internal modem as digital data and sends it to the sound system so the user can hear the status of a dial-up modem connection. The level of the call progress audio is fixed.
Digital audio data from the DVD-ROM/CD-RW Combo drive is processed by the Sound Manager. The data is then transferred by DMA through the I2S interface of the Pangea IC to the Tumbler sound system, where the digital data is converted to analog signals and sent to the speaker and the A/V jack.