iPhone OS Audio Routes

Getting audio signals into and out of an iPhone OS device can sometimes be a bit tricky. The information presented below outlines the available means for getting audio signals into and out of each iPhone OS device.

Available Input Routes

Built-in mic Headset input Dock input
iPhone Yes(1) Yes Yes
iPhone 3G Yes Yes Yes
iPod touch No No Yes(2)
iPod touch 2G No Yes Yes
  1. The built-in microphone of the original iPhone appears to be routed through a speech-processing codec, which limits the sample rate to 8 kHz and significantly degrades the frequency response.
  2. Using a dock connector input with the original (1st generation) iPod touch appears to require that something be plugged into the headphone jack, unless the dock connector device also supports audio output (like the Macally iVoice Pro, which, ironically, is one of the few devices that is narrow enough to allow you to plug your headphones into the bottom of the iPod).

Available Output Routes

Receiver Speaker Headphones Dock
iPhone Yes(1) Yes(1) Yes Yes
iPhone 3G Yes Yes Yes Yes
iPod touch No No Yes Yes
iPod touch 2G No Yes Yes Yes
  1. Even when using the dock connector for input, if the receiver or built-in speaker is the current output device on the original iPhone, the sample rate will be limited to 8 kHz (for input and output).

Links to additional information:

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