Unity Editor script to customize importing audio with various configurations.

CBAudioImport.cs

using UnityEditor;
using UnityEngine;

/// <summary>
/// Modify the way audio is imported into Unity
/// Throw this script in the Editor folder. 
/// Place audio files in folders named with specific keywords listed below to automate how they are imported. 
/// Check Unity reference for details and such
/// </summary>
public class CBAudioImport : AssetPostprocessor
{
    const string forceToMonoKeyword = "mono";
    const string iosHardwareDecoding = "ios";
    /* The method Unity uses to load audio assets at runtime.
     * Audio files will be decompressed as soon as they are loaded. 
     * Use this option for smaller compressed sounds to avoid the performance overhead of decompressing on the fly. 
     * Be aware that decompressing sounds on load will use about ten times more memory than keeping them compressed, so don't use this option for large files. */
    const string sfxKeyword = "sfx";
    /* Keep sounds compressed in memory and decompress while playing. 
     * This option has a slight performance overhead (especially for Ogg/Vorbis compressed files) so only use it for bigger files 
     * where decompression on load would use a prohibitive amount of memory. 
     * Note that, due to technical limitations, this option will silently switch to Stream From Disc for Ogg Vorbis assets on platforms that use FMOD audio. */
    const string sfxLargeKeyword = "large";
    /*  Stream audio data directly from disc. 
     * The memory used by this option is typically a small fraction of the file size, so it is very useful for music or other very long tracks. 
     * For performance reasons, it is usually advisable to stream only one or two files from disc at a time but 
     * the number of streams that can comfortably be handled depends on the hardware. */
    const string musicKeyword = "music";
    const string loopKeyword = "loop";
    const string threeD = "3d";

    /// <summary> Audio importer lets you modify AudioClip import settings using keyword named folders. </summary>
    public void OnPreprocessAudio()
    {
        AudioImporter audioImporter = (AudioImporter)assetImporter;

        // Compression bitrate in bits/second, e.g. 128000 would be 128 kbps. - Native or Ogg compressed.
        Debug.Log(string.Format("Importing:{0} - {1} bits/second - {2}", assetPath, audioImporter.compressionBitrate, audioImporter.format.ToString()));

        // Force this clip to mono?
        if (assetPath.Contains(forceToMonoKeyword))
            audioImporter.forceToMono = true;

        // Use hardware voice/decoder (Apple hardware codec) on iOS.
        if (assetPath.Contains(iosHardwareDecoding))
            audioImporter.hardware = true;

        // The method Unity uses to load audio assets at runtime.
        if (assetPath.Contains(sfxKeyword))
            audioImporter.loadType = AudioImporterLoadType.DecompressOnLoad;
        else if (assetPath.Contains(sfxLargeKeyword))
            audioImporter.loadType = AudioImporterLoadType.CompressedInMemory;
        else if (assetPath.Contains(musicKeyword))
            audioImporter.loadType = AudioImporterLoadType.StreamFromDisc;
        
        // Is this clip loopable?
        audioImporter.loopable = assetPath.Contains(loopKeyword);
        
        // Is this clip a 2D or 3D sound?
        audioImporter.threeD = assetPath.Contains(threeD);
    }
}