Did Raspberry Pi 3 add audio input? I'm new to RPi and interested in doing speech recognition but noticed input has been missing for previous versions.
If it hasn't, what is the best way for me to go about recognizing speech on RPi3? Thank you.
That is correct, there is no audio input. The Pis generate analogue audio output using simple pulse width modulation (PWM) which is an efficient way to make output audio, but in the case of the Pi, it lacks great analogue separation. To get audio input, the Pi would have to have a dedicated audio codec, which it doesn't.
A lot of people mention USB sound cards which can readily be used with the Pi systems. There are other GPIO based sound cards which can also provide input audio lines ... check here for a non comprehensive list. Some of them also have microphones built in or microphone inputs, or lastly line inputs with which you can use a microphone preamp.
USB sound cards tend to have longer latencies (mode delay) as they have to buffer audio to send over USB (using the UAC/UAC2 protocol).
You can use one of those USB sound cards, or if you don't want to hog up USB ports but don't mind using the GPIO pins, you can use the Cirrus Logic Sound Card (audiophile-grade hardware though, fairly expensive)
I found a widget that looks just like a minimal, right angle USB adapter to phone jack for a 3.5mm headset. I haven't had time to wring it out yet. I'm not sure I know the raspbian tricks to get it open as an input. I like simple and small and special purpose (if it works.)