Microphone.Start
static function Start(deviceName: string, loop: bool, lengthSec: int, frequency: int): AudioClip;
static AudioClip Start(string deviceName, bool loop, int lengthSec, int frequency);
static def Start(deviceName as string, loop as bool, lengthSec as int, frequency as int) as AudioClip
Parameters

deviceName The name of the device.
lengthSec Is the length of the AudioClip produced by the recording.
loop Indicates whether the recording should continue recording if lengthSec is reached, and wrap around and record from the beginning of the AudioClip.
frequency The sample rate of the AudioClip produced by the recording.
Returns
AudioClip The function returns null if the recording fails to start.
Description

Start Recording with device.

If you pass a null or empty string for the device name then the default microphone will be used. You can get a list of available microphone devices from the devices property. You can find the range of sample rates supported by a microphone using the GetDeviceCaps property.

Note that if you want to use the Microphone class in the web player, you need to get the user's permission to do so. Call Application.RequestUserAuthorization before calling any Microphone methods.
	// Start recording with built-in Microphone and play the recorded audio right away
	function Start() {
		audio.clip = Microphone.Start("Built-in Microphone", true, 10, 44100);
		audio.Play();
	}
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Start() {
        audio.clip = Microphone.Start("Built-in Microphone", true, 10, 44100);
        audio.Play();
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Start() as void:
		audio.clip = Microphone.Start('Built-in Microphone', true, 10, 44100)
		audio.Play()