Version: 2018.1
public bool forceToMono ;

説明

ステレオから強制的にモノラルにします

    // Import files containing "mono" in their name as mono.
    class DetectMono extends AssetPostprocessor {
        function OnPreprocessAudio () {
            if (assetPath.Contains("mono")) {
                var audioImporter : AudioImporter = assetImporter;
                audioImporter.forceToMono = true;
            }
        }
    }