Those people might be interested in Symphonica, a wooden horn, that's designed for phones, and which can apparently boost the sound from your phone speaker "by up to 6dB", while adding "warmth" to the sound.
Not just a pretty horn, it can also charge your phone thanks to the docking stand, and there's even a wooden Bluetooth remote.
If you want to back the project, $85 (around £70) will get you the natural wood version, while $115 (around £90) will snag you the dark wood. Shipping is predicted for July 2017. Full details are here.