Last week at Hearing International we reviewed the military’s need to jam signals in the operation areas. As we found out it basically saved the lives of soldiers deployed to various areas where hostile action was required. This week Hearing International investigates the actual issue of if buzzing is caused in cochlear implants by signal jamming and if so what causes the “Buzzing”.
As discussed last week, the purpose of signal jamming by the military is a practice that is conducted regularly. The physics of jamming a cell phone are actually quite simple. Cell phones operate by sending signals along a range of the electromagnetic spectrum reserved for their use. In the United States most cell phone companies use the CDMA standard that that typically transmits on either 800 or 1,900 megahertz; in Europe most phones use the GSM standard and the frequency usually 900 or 1,800 megahertz.), in other parts of the world it might be another frequency, but most of the world has either adopted the US or the European versions. All a cell phone jamming device needs to do is broadcast a signal on those same frequencies, and it will interfere with any devices trying to transmit in that range. Jamming devices, illegal for civilian use in the US, overpower the cell phone by transmitting a signal on the same frequency and at a high enough power that the two signals collide and cancel each other out. Cell phones are designed to add power if they experience low-level interference, so the jammer must also recognize and match the power increase from the phone. The net effect for a hapless cell-phone user is that the phone’s screen will simply indicate that no signal is available. Odds are most people won’t even notice that their phones are being jammed. They’ll just assume that they’re in a dead spot—and feel annoyed. Or terroists will be frustrated that they cannot remotely activate their explosive devices.
Enter the innocent cochlear implant patient in a military operations area. Click here for a video of how a cochlear implant operates. Normally, their implant operates with a transmitter sending signals from a usually a behind the ear (BTE) processor/transmitter to the implant inside of their head which sends the signal to electrodes that communicate with the cochlea and, subsequently, to the auditory nerve and pathways. Cochlear implants andtheir use with cellphones are described at Hub pages.com. Just as the jammer interferes with the signals for cell phone transmission, it interferes with the transmission of the signal from the processor/transmitter. Since the jamming device causes a constant collision with the radio frequency signal, the “buzzing” can be constant as long as the signal continues to be jammed.
In the Middle East, the primary area of current US military operations, the incidence of profound sensori-neural hearing impairment aas well as other exceptionalities is about 25% greater than in other parts of the world due to consaiguous marriage. Cochlear implants are quite popular in the Middle East as they a are beneficial for profound hearing impairment, often a government funded, and offer a relatively cosmetic given the customary attire of the region. Although the potential for problem patients from signal jamming will probably increase as the use of cochlear implants increase, Dr. Tarek El Dousseki, MD, indicates that this issue appears to be difficulty for cochlear implant users isolated to a small geographical area where military operations are found. The answer then to our Hearing International question this week is that jamming really does cause buzzing within cochlear implants in close proximity to the signal jamming devices. For those patients that are plagued with this problem, it is a major issue that affects them routinely. It is best for them to, if possible, to stay out of the range of the jamming devices or to turn off the implant while the jamming is present.
For cochlear implant users interested, Gallaudet University is conducting a study to evaluate interference in cochlear implants from digital cellular telephones. Their study is of cochlear implant patients that experience a “buzzing sound” when using a wireless phone which is caused by electromagnetic interference. This type of research could lead to help for those that are experiences this buzzing as a reault of jamming. Click on the links to get the Gallaudet site and register for their study.