Audio play volume is too low in iphone devices after call microphone recording service

Am using this code

 IEnumerator LoadAudio()    
 {
 www = new WWW("local device location for audio");
 yield return www;
 if (www.error != null)
 {
 Debug.Log(www.error);
 }
 else
 {
 source.clip = www.GetAudioClip();
 source.Play();
 }
 }
 

First time works with good volume of sound and then call iphone recording service (for Speech to text), After that call same method second time audio volume too is low in iphone device.Am using unity version 2019.2.17f1.Note: without call Microphone service volume works fine.Not working even using this code iPhoneSpeaker.ForceToSpeaker(); from this source https://github.com/reivendark/UnitySpeakerFix_iOS7plus