Hello, I am developing a native CarPlay application and would appreciate some clarification regarding AVAudioSession behaviour when using the vehicle microphone. The application is intentionally simple and designed to minimise driver distraction. The user presses a single button on the CarPlay screen, the application performs a brief (approximately five second) audio capture, performs application-specific processing on the captured audio, displays a simple confirmation to the user, and immediately releases the audio session. The goal is to allow the driver to continue their journey with as little interaction as possible. Because the audio being captured is often originating from the vehicle’s native DAB/FM radio rather than from the iPhone itself, preserving the existing listening experience during the brief capture is fundamental to the intended design. To better understand what is supported by CarPlay, I have carried out a number of controlled experiments. Test Environment Native CarPlay application Swift AVFoundation AVAudioSession AVAudioRecorder Vehicle connected via CarPlay Vehicle playing its native DAB radio Experiment 1 Configuration Category: AVAudioSession.Category.playAndRecord Mode: AVAudioSession.Mode.default Observed Route Input: CarPlay — CarAudio Output: CarPlay — CarAudio Result Recording succeeds using the vehicle microphone. Native DAB audio is muted during recording. The vehicle changes from “Audio Volume” to “Voice Volume”. When recording finishes and the AVAudioSession is deactivated, DAB resumes normally. Experiment 2 Changed only the session mode to: AVAudioSession.Mode.measurement Result Behaviour was identical to Experiment 1. Experiment 3 Changed only the session mode to: AVAudioSession.Mode.videoRecording Observed Route Input: iPhone microphone Output: CarPlay — CarAudio Result Input automatically switched from the vehicle microphone to the iPhone microphone. The vehicle remained in normal “Audio Volume”. However, the head unit switched away from its native DAB source to the CarPlay media source. Observation These experiments appear to suggest that the behaviour is specifically related to using the CarPlay “CarAudio” microphone route, rather than audio recording itself. Question Is this the expected behaviour for third-party CarPlay applications? More specifically: Is there any supported AVAudioSession configuration or CarPlay API that allows a third-party CarPlay application to perform a brief, user-initiated audio capture using the vehicle microphone without causing the head unit to enter its communications/voice audio mode or interrupt the vehicle’s native radio playback? If this behaviour is by design and no supported mechanism exists to achieve this, confirmation of that would be extremely valuable, as it would allow us to design the application accordingly. If additional information, sample code, AVAudioSession logs or detailed reproduction steps would be helpful, I would be more than happy to provide them. Thank you very much for your time. Kind regards, Neil Jenner Developer, HearSave

Title AVAudioSession microphone recording changes Bluetooth audio route in vehicle Hi everyone, I’m developing an iOS app called HearSave to help drivers safely remember and save songs they hear while driving. The app performs a very simple task: the user presses a button, the app records a short audio sample for music recognition, then immediately stops recording. I’m trying to understand whether the behaviour I’m seeing is an expected limitation of iOS audio routing or whether there is a better AVAudioSession configuration. Test setup iPhone connected to a vehicle via Bluetooth. Vehicle playing DAB radio. App requests microphone access and starts recording. Recording lasts approximately 7 seconds. Behaviour observed As soon as recording begins: The vehicle changes into a voice-call style audio route. DAB audio becomes muted. The vehicle’s volume control changes to voice volume. When recording finishes, the radio does not automatically recover until the user manually changes the audio source away from DAB and back again. I’ve experimented with several Expo Audio / AVAudioSession configurations, including releasing the audio session immediately after recording and adjusting audio session options, but the behaviour remains the same. My questions Is this expected behaviour when an iOS app starts microphone recording while connected to a vehicle over Bluetooth? Is there an AVAudioSession configuration that allows brief microphone capture without causing the vehicle to switch audio routes? Is it possible to explicitly use the iPhone’s built-in microphone while remaining connected to the vehicle via Bluetooth? If this behaviour is unavoidable over Bluetooth, is this also expected behaviour for native CarPlay apps, or are different audio routing capabilities available to CarPlay applications? Any guidance or documentation would be greatly appreciated. Thank you.