AlarmManagerで設定時間に音(SoundPool)が鳴らない

Question

android studioでkotlinにてアラーム機能を実装しようとしております。

〇やりたいこと
設定時間に通知(Notification)と音(SoundPool)を出したい
以下コードは5s後に通知されるように書いています

〇困っていること
指定時間にSoundPoolの処理を通過しているものの音が鳴らない

class MainActivity : FragmentActivity(), TimePickerDialog.OnTimeSetListener {

    private lateinit var binding: ActivityMainBinding
    private lateinit var soundManager: SoundManager 

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        soundManager = SoundManager(this)

        binding.btnTest.setOnClickListener {
            alarmSet()
        }
    }

    private fun alarmSet() {
        val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
        val calendar = Calendar.getInstance()

        var year = calendar.get(Calendar.YEAR)
        var month = calendar.get(Calendar.MONTH)
        var day = calendar.get(Calendar.DAY_OF_MONTH)

        val intent = Intent(this, MyReceiver::class.java)
        val pendingIntent = PendingIntent.getBroadcast(
            this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT
        )

        calendar.add(Calendar.SECOND, 5)
        alarmManager.setExact( 
            AlarmManager.RTC_WAKEUP,
            //calendar.getTimeInMillis(),
            calendar.timeInMillis,
            pendingIntent
        )
    }

    fun playOneReady() {
        soundManager.playOne()
    }

class MyReceiver: BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        if (context != null) {
            MyNotification.sendNotification(context)
        }
    }
}

class MyNotification(context: Context) {

    companion object {
        private const val NOTIFICATION_CHANNEL_ID = "com.example.sample_alarm_manager_channel_id"
        private const val NOTIFICATION_CHANNEL_NAME = "Time for !!"
        private const val NOTIFICATION_CHANNEL_DESCRIPTION = "Go To The"
        private const val NOTIFICATION_TITLE = "sample alarm manager"
        private const val NOTIFICATION_MESSAGE = "test message."

        fun sendNotification(context: Context) {
            Log.d("debug", "MyNotification sendNotification")

            val channelId = Companion.NOTIFICATION_CHANNEL_ID
            val channelName = Companion.NOTIFICATION_CHANNEL_NAME
            val channelDescription = Companion.NOTIFICATION_CHANNEL_DESCRIPTION

            //Android 8.0 以上ではアプリの通知チャンネルを登録することが必要。
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                val importance = NotificationManager.IMPORTANCE_DEFAULT
                val channel = NotificationChannel(channelId, channelName, importance).apply {
                    description = channelDescription
                }
                val manager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
                manager.createNotificationChannel(channel)
            }

            //通知をシステムに登録しています。
            val builder = NotificationCompat.Builder(context, channelId).apply {
                setSmallIcon(R.drawable.ic_baseline_info_24)
                setContentTitle(Companion.NOTIFICATION_TITLE)
                setContentText(Companion.NOTIFICATION_MESSAGE)
                priority = NotificationCompat.PRIORITY_DEFAULT
            }

            val id = 0
            NotificationManagerCompat.from(context).notify(id, builder.build())

            val mainActivity = MainActivity()
            mainActivity.playOneReady()
        }
    }

}

class SoundManager(context: Context) {

    private var soundPool: SoundPool
    private var soundOne = 0
    private var streamId2 = 0

    init {
        //soundPool設定
        val audioAttributes = AudioAttributes.Builder()
            .setUsage(AudioAttributes.USAGE_GAME)
            .setContentType(AudioAttributes.CONTENT_TYPE_SPEECH)
            .build()

        soundPool = SoundPool.Builder()
            .setAudioAttributes(audioAttributes)
            .setMaxStreams(1)
            .build()

        soundOne = soundPool.load(context, R.raw.bivlla, 1)
        Log.d("debug", "SoundManager init")
    }

    fun playOne() {
        cancelOne()
        streamId2 = soundPool.play(soundOne, 1.0f, 1.0f, 0, -1, 1.0f)
        Log.d("debug", "sound ringing")
    }

    fun cancelOne() {
        if(streamId2 != 0) {  //fun playOneを通るとここを通る(音が鳴るとstreamId2= 1 が入る)
            soundPool.stop(streamId2)
            streamId2 = 0
        }
    }
}