Record audio in Day One. This is a Premium feature. Users can record up to 3 hours per recording (without transcription) and have up to 30 recordings in a single entry. Audio is recorded in .m4a file format.
Transcription to text is available and can be enabled in Day One > Settings > Advanced > Transcribe to Text. Transcribed audio can be up to 10 minutes. Day one will use the device language you have set for your transcription.
iOS
Recording
Tap the microphone icon on the Timeline to begin recording audio. Long press on the microphone icon to Broswe (from the Files app), choose (one time) to record with transcription or standard.

You will see the time remaining for the recording at the top left. Tap the red Stop icon at the top right when finished recording.

In an existing entry, tap the 📎 (paper clip) icon above the keyboard and tap the microphone to start recording. Tap File for the option to view audio recordings in the Files app (an existing audio entry, .m4a only).

Audio recording is now available on Apple Watch beginning in our 3.2 update for iOS. Transcription with Audio Recording is not currently available via Apple Watch.

Playback
In an existing entry with audio, tap the audio icon to begin playback. You can scrub forward or backward on the audio timeline.

Transcription
Transcribing your audio to text is limited to 10 minutes. The default can be enabled/disabled in Day One > Settings > Advanced > Transcribe to Text.

Importing audio from other sources
Long Press on the Microphone icon on the main Timeline page or inside of an entry and choose Add File… to add an .m4a file from another location like iCloud Drive or Dropbox.
You can also import audio from other locations by using the share extension to Day One from that other source. For example, if you have audio in the Voice Memos app, you can share it to Day One. Open Voice Memos > choose a recording > tap the More (•••) button at the bottom left > Share.
Choose Day One in the share extension > include any text or adjust the journal and add tags if desired > Tap Save. Supported audio format: .m4a
Exporting audio from Day One
Tap the More icon (•••) on the audio file and choose to Share.

macOS and Android
This section will be updated as soon as audio is ready for those platforms.