الفهرس 
ANATOMY OF THE HEARING SYSTEMOnly 14 pages are availabe for public view
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Abstract
There is widespread public concern about the potential adverse health effects of mobile phones and especially their associated base-stations. Alongside this there are hundreds of reports in the media about the health effects of mobile phones & base-stations. The scientific literature is large and confusing, also apparently showing very inconsistent effects across studies.
Most studies on human hearing insults from use of cellular phones are controversial studies, many reports and reviews have been published, most concluding that there is little evidence for any adverse health effects that can be attributed to mobile phone base-stations such as:
• Royal Society of Canada (1999) conducted Surveys in proximity to base stations operating in Canada and indicated that the public is exposed to extremely low intensity radiofrequency fields in the environment.
• Institute of Electrical & Electronics Engineers (IEEE, 2001) report that public exposure to radiofrequency fields near wireless base stations is far below recommended safety limits, consequently, wireless base stations are not considered to present a risk to the general population.
• U.K. Advisory group on Non-Ionizing Radiation (2003) note that exposure levels from living near to mobile phone base-stations are extremely low, and the overall evidence indicates that they are unlikely to pose a risk to health.”
Also there are studies demonstrating that 10, 15, 20 and 30 minutes of Global System for Mobile Communications mobile exposure did not induce a measurable effect on the human auditory system as Hyland, 1999, do.
In addition there are studies based on auditory brainstem response and middle latency response concluded that 30 minutes of mobile phone use has no short-term adverse effects on the human auditory system by Penafiel et al, 1997.
On the other hand there are studies reported risky effects of mobile phone use on hearing. For example, Alsanosi et al, 2013, reported that use of mobile phone for 60 minutes daily for 3 years had significant effects on hearing threshold levels and distortion products otoacoustic emission in the test-ears, while non test-ears did not show any significant effect.
This present results show a significant effect after a prolonged period of mobile phone use for 60minutes on 1000 Hz and 2000 Hz frequencies and average pure tone audiogram on the test-ears.
At the same time, distortion products otoacoustic emission amplitudes decreased significantly at 1000, 1400, and 2000 Hz and average amplitudes in test-ears after exposure.
Similar results were reported by Shcheglov et al, 1997, in the form of mild hearing loss in mobile phone users.
Also, Naresh Panda et al, 2011 reported that mobile phone users were found to have subclinical hearing loss, which could be bilateral and that they were more related to duration of usage (both daily and cumulative) than the type of communication protocol.
This controversy depend on duration of usage (both daily and cumulative), type of communication protocol, size of the study population, site of impact as central or peripheral auditory system, nature of bad effects if it is thermal or non thermal and radiofrequency signals if it is modulated or not as Hyland (2000) argued that amplitude-modulated and pulse-modulated radiofrequency energy might have different effects than continuous-wave (unmodulated) radiofrequency energy.
This could well be important because mobile phones and their base-stations produce a modulated signal, and much of the research has been done with unmodulated radiofrequency sources. Foster & Rapacholi (2004) Point out that no clear biological mechanisms have been established to explain how modulation might affect responses. Future research should be directed at confirmation and mechanistic understanding of reported biological effects related to modulation.
Many scientific studies also note that there are insufficient well-controlled studies to draw any firm conclusions.
Some have argued that laboratory-based studies have used artificial sources of radiofrequency energy making it difficult to generalize to the normal working & living environment.
This lead to conclude that there are two factors that had a significant impact on the magnitude of auditory functions secondary to mobile phone usage. First, total cumulative use equal to or more than 3 years was found to be a risk factor. Global System for Mobile Communications phones users with usage more than 3 years were found to be at a higher risk of having distortion products otoacoustic emissions absent in the mobile using ear as compared with subjects with less than 3 years of use. A similar trend was seen with Code Division Multiple Access phone users in their middle latency response amplitude which also diminished. Second factor is an average daily usage more than 1 hour was found to be a risk factor, specially with Global System for Mobile Communications users, they were predisposed to a higher risk of absent distortion products otoacoustic emissions in the mobile using ear as compared with users with an average daily use of 30 to 60 minutes.
In conclusion, mobile phones had an immediate and adverse effect on hearing documented subjectively and objectively on young human subjects. It also caused other otologic symptoms. Future research is recommended to assess the recovery and progress of the acute changes in the auditory system.