CNI Bone Conduction Audio System

Bone-conduction transducers soldered to the cable. The cloth and felt covers are also shown.

Close-up of th bone-conduction transducers soldered and hot-glued.

Newmatic audio amplifier.

At the CNI, we have built and maintain an MR-compatible bone conduction audio system. The system is driven by the Newmatic amplifier box.

Parts

1. Newmatic amplifier box
2. Two Sonitron blue-line transducers. We build two sizes to accommodate adults and small children-- 41mm and 53mm. I have yet to find a US-source for these, but you can order them from RS Exports (53mm and 41mm)
3. 3.5mm to dual RCA 10 foot cable (e.g., this one from Amazon)
4. 3.5mm to dual RCA male jack adapters (e.g., this one from Amazon)
5. Two RCA female to BNC male adaptors (e.g., these from Amazon)
6. Two BNC all-female T-connectors (e.g., these from Amazon)
7. Cloth to cover the transducers

Instructions

• Cut the RCA jacks off of the 10-foot cable.
• Solder each pair of wires to one of the transducers. Keep the paper cover on the back-side of the transducers so the Piezo element is not exposed.
• Use hot glue to neatly secure the wires to plastic shell and create a strain-relief. Ensure that all exposed copper and solder is well-insulated.
• Attach the 3.5mm to dual RCA male cable to the Newmatic BNC wires in the scan room. (The BNC T-connector allows you to also connect the Newmatic air-tube transducer if you like.)
• Plug the 3.5mm male jack on the 10-foot wire into the 3.5mm female.
• Cover the transducers with cloth. We use a felt inner-covering and a cloth outer covering, both sewn tight around the transducers.