if you're willing to get your hands dirty you can use this tool to turn images into wavetables, where each pixel on the y axis represents an audio sample and the x-axis represents the wavetable position. from experience I can say it works amazingly with texture creation tools like substance designer that works with the power of 2 resolutions and have a large variety of generative algorithms. or you can use less powerful but free alternatives like TextureLab and Material Maker.