What are the main differences between free-key and fixed-key African xylophones?

In African music, xylophones are generally categorized into two distinct types based on their construction: free-key and fixed-key instruments.1

Free-Key Xylophones

These instruments are characterized by loose, unattached keys. The slabs are typically laid across a player’s outstretched legs, logs, or straw bundles, and they are sometimes positioned over a resonating pit. Because the keys are not permanently mounted, this design is relatively simple and portable.12

Fixed-Key Xylophones

Fixed-key xylophones are more elaborate in their construction. In these versions, the keys are secured in a frame, often arranged in an arc that the player holds in front of them. A defining feature of many fixed-key instruments is the inclusion of individually tuned calabash resonators mounted beneath each key. These resonators frequently incorporate a mirliton—a vibrating membrane—which adds a characteristic buzzing quality to the sound. While free-key xylophones are common in parts of West and East Africa, fixed-key versions are central to complex musical traditions, such as the timbila orchestras of the Chopi people in Mozambique.12