This case involves an allegedly defective model of headphones that exploded. The plaintiff was using her headphones while biking in 95-degree weather and was sweating profusely. As the headphones became wet, they began to smoke and spontaneously exploded, causing severe facial burns to the plaintiff. The product was marketed as noise canceling and water resistant headphones that could withstand rough treatment and exposure to the elements. An expert in acoustics with experience in headphone testing and technology was sought to comment on the alleged defect of the products, specifically its lack of durability and water resistance.
Question(s) For Expert Witness
- 1. Please describe your experience with designing and/or testing headphones, particularly as it relates to durability and waterproofing.
- 2. Please describe your methodology to determine if these headphones are defective.
Expert Witness Response E-023343
I have been building wearable computers for over 15 years for a company that builds electronics and power management modules and deploys waterproof solutions extensively. In many studies, including a current study of aquatic cardiac rehab, we use waterproof/water resistant devices and electronics. Almost all of our devices are battery operated and we carefully design our systems to meet the specifications and requirements in terms of power delivery and battery lifetime. We consider the limitations of batteries in our designs and incorporate techniques to minimize the adverse impacts. We have also disassembled electronic devices in many cases to identify the cause of failures or to determine the existence of specific parts or electronic components.
As for the methodology to determine if this product is defective, I would first disassemble the headphones and inspect the component under a microscope to identify any potential physical faults. I would carefully inspect the seal for the enclosure. I would power up the headphones and use an oscilloscope and other electronic test equipment to observe electrical signals on various accessible test points or electronic components. Once the potential cause of failure is determined, I would attempt to perform a fix and place the headphones under humidity stress and determine if similar failures will appear again. I would also perform several function and stress tests at various levels of humidity or water and determine potential sources of failures. I have reviewed a number of cases studying and investigating the wearability of commercial and consumer electronic devices.