diff --git a/src/audioInput.js b/src/audioInput.js
new file mode 100644
index 0000000..aa845f7
--- /dev/null
+++ b/src/audioInput.js
@@ -0,0 +1,85 @@
+export const AUDIO_INPUT_ENABLED_KEY = 'audioInputEnabled'
+export const AUDIO_INPUT_DEVICE_ID_KEY = 'audioInputDeviceId'
+
+const AUDIO_RECORDER_MIME_CANDIDATES = [
+  'audio/webm;codecs=opus',
+  'audio/webm',
+  'audio/mp4',
+  'audio/ogg;codecs=opus',
+  '',
+]
+
+export function supportsAudioInputCapture() {
+  return (
+    typeof navigator !== 'undefined' &&
+    typeof window !== 'undefined' &&
+    typeof window.MediaRecorder !== 'undefined' &&
+    Boolean(navigator.mediaDevices?.getUserMedia) &&
+    Boolean(navigator.mediaDevices?.enumerateDevices)
+  )
+}
+
+export function getAudioInputConstraints(deviceId = '') {
+  const audio = {
+    echoCancellation: true,
+    noiseSuppression: true,
+    autoGainControl: true,
+  }
+
+  if (deviceId) {
+    audio.deviceId = { exact: deviceId }
+  }
+
+  return { audio }
+}
+
+export function stopMediaStream(stream) {
+  stream?.getTracks?.().forEach(track => track.stop())
+}
+
+export async function ensureAudioInputPermission() {
+  if (!supportsAudioInputCapture()) {
+    throw new Error('Microphone capture is not available in this environment.')
+  }
+
+  const stream = await navigator.mediaDevices.getUserMedia({ audio: true })
+  stopMediaStream(stream)
+}
+
+export async function listAudioInputDevices() {
+  if (!supportsAudioInputCapture()) {
+    return []
+  }
+
+  const devices = await navigator.mediaDevices.enumerateDevices()
+  return devices
+    .filter(device => device.kind === 'audioinput')
+    .map((device, index) => {
+      const label = String(device.label || '').trim()
+      return {
+        deviceId: device.deviceId || `audio-input-${index + 1}`,
+        label: label || `Microphone ${index + 1}`,
+        hasLabel: Boolean(label),
+      }
+    })
+}
+
+export function getPreferredAudioRecorderMimeType() {
+  if (typeof window === 'undefined' || typeof window.MediaRecorder === 'undefined') {
+    return ''
+  }
+
+  for (const mimeType of AUDIO_RECORDER_MIME_CANDIDATES) {
+    if (!mimeType) {
+      return ''
+    }
+    if (
+      typeof window.MediaRecorder.isTypeSupported !== 'function' ||
+      window.MediaRecorder.isTypeSupported(mimeType)
+    ) {
+      return mimeType
+    }
+  }
+
+  return ''
+}