Purpose: The potential demand for hearing aids is increasing in accordance with aging of populations in many developed countries. Because certain patients cannot use air conduction hearing aids, they usually use bone conduction hearing aids. However, bone does not transmit sound as efficiently as air, and bone conduction hearing aids require surgery (bone anchored hearing aid) or great pressure to the skull. The first purpose of this study is to examine the efficacy of a new sound conduction pathway via the cartilage. The second purpose is to develop a hearing aid with a cartilage conduction transducer for patients who cannot use regular air conduction hearing aids. Design/methodology/approach: We examined the hearing ability of a patient with atresia of both external auditory meatuses via three kinds of conduction pathways (air, bone, and cartilage). After the best position for the cartilage conduction transducer was found, audiometric evaluation was performed for his left ear with an insertion earphone (air conduction), a bone conduction transducer, and a cartilage conduction transducer. Then we made a new hearing aid using cartilage conduction and got subjective data from the patients. Findings: The tragal cartilage was the best position for the cartilage conduction transducer. The patient’s mean hearing levels were 58.3 dBHL, 6.7 dBHL, and 3.3 dBHL for air conduction, bone conduction, and cartilage conduction respectively. The hearing ability of the patients obtained from the cartilage conduction hearing aid was comparable to those from the bone conduction hearing aid. Practical implications: Hearing levels using cartilage conduction are very similar to those via bone conduction. Cartilage conduction hearing aids may overcome the practical disadvantages of bone conduction hearing aids such as pain and the need for surgery. Originality/value: We have clarified the efficacy of the cartilage conduction pathway and developed a prototype ‘cartilage conduction hearing aid’, which is the first hearing aid to use sound transmission via cartilage.