What causes interference between digital cell phones and hearing aids?
When using a digital cell phone, the telephone conversation is transmitted over a wireless network using radio waves. The radio waves emitted by the cell phone are referred to as radio-frequency (RF) emissions. The RF emissions create an electromagnetic (EM) field around the phone’s antenna. This EM field has a pulsing pattern. It is this pulsing energy that may potentially be picked up by the hearing aid’s microphone or telecoil circuitry and perceived by the hearing aid wearer as a buzzing sound. To complicate matters, the technology for transmitting calls over a wireless network differs depending on the carrier or service provider. For example, Verizon Wireless and Sprint PCS use CDMA technology, Nextel uses iDEN technology, and AT&T Wireless, Cingular Wireless and T-Mobile use GSM technology. The interference generated by these various technologies has different characteristics, some of which may cause more annoying interference for hearing aid users than others. Telecoil users may
