AudioRecorder.swift

import AVFoundation

actor AudioRecorder {
    private let audioEngine = AVAudioEngine()
    #if os(iOS)
    private let audioSession = AVAudioSession.sharedInstance()
    #endif
    
    static func authorize() async -> Bool {
        await withCheckedContinuation { continuation in
            AVCaptureDevice.requestAccess(for: .audio) { granted in
                continuation.resume(returning: granted)
            }
        }
    }
    
    func stream() async throws -> AsyncStream<AVAudioPCMBuffer> {
        #if os(iOS)
        try await audioSession.setCategory(.record, mode: .measurement, options: .duckOthers)
        try await audioSession.setActive(true, options: .notifyOthersOnDeactivation)
        #endif
        
        let inputNode = audioEngine.inputNode
        let recordingFormat = inputNode.outputFormat(forBus: 0)
        
        let audioStream = AsyncStream<AVAudioPCMBuffer> { continuation in
            inputNode.installTap(onBus: 0, bufferSize: 1024, format: recordingFormat) { (buffer: AVAudioPCMBuffer, when: AVAudioTime) in
                continuation.yield(buffer)
            }

            continuation.onTermination = { termination in
                Task {
                    await self.terminate()
                }
            }
        }
        
        audioEngine.prepare()
        try audioEngine.start()
        
        return audioStream
    }
    
    private func terminate() {
        audioEngine.stop()
        audioEngine.inputNode.removeTap(onBus: 0)
    }
}

Don't forget to add Audio Input capability and NSMicrophoneUsageDescription!