Federica Sibella

Effects of UMTS cellular phones on human hearing: results of the European project EMFnEAR.

Abstract The European project EMFnEAR was undertaken to assess potential changes in human auditory function after a short-term exposure to radiofrequency (RF) radiation produced by UMTS (Universal Mobile Telecommunication System) mobile phones. Participants were healthy young adults with no hearing or ear disorders. Auditory function was assessed immediately before and after exposure to radiofrequency radiation, and only the exposed ear was tested. Tests for the assessment of auditory function were hearing threshold level (HTL), distortion product otoacoustic emissions (DPOAE), contralateral suppression of transiently evoked otoacoustic emission (CAS effect on TEOAE), and auditory evoked potentials (AEP). The exposure consisted of speech at a typical conversational level delivered via an earphone to one ear, plus genuine or sham RF-radiation exposure produced by a commercial phone controlled by a personal computer. Results from 134 participants did not show any consistent pattern of effects on the auditory system after a 20-min UMTS exposure at the maximum output of the phone with 69 mW/kg SAR in the cochlea region in a double blind comparison of genuine and sham exposure. An isolated effect on the hearing threshold at high frequencies was identified, but this was statistically nonsignificant after correction for multiple comparisons. It is concluded that UMTS short-term exposure at the maximum output of consumer mobile phones does not cause measurable immediate effects on the human auditory system.

Assessment of SAR in the tissues near a cochlear implant exposed to radiofrequency electromagnetic fields

Cochlear implants (CI) are electronic devices used to restore partial hearing to people with severe hearing impairment. This paper aims to investigate if the introduction of a CI has an effect on SAR distribution in a head model exposed to radiofrequency electromagnetic fields (RF EMF) at mobile communication frequencies. The head model was obtained by image segmentation, the implant was modelled as a geometric structure and the exposure source was modelled as a uniform plane wave at 900 MHz, 1750 MHz and 1950 MHz, incident on the side of the head with the CI. Vertical and horizontal polarizations were simulated. Results show that the presence of a CI inside the cochlea produces negligible variations in the averaged SAR values, both in the head and in the cochlear tissues, although very localized differences in point SAR were found in the cochlea. Globally, these results suggest that finding harmful effects in the cochlear tissues will be unlikely.

Assessment of the exposure to WLAN frequencies of a head model with a cochlear implant

In the last few years, significant developments have taken place in the field of Wireless Local Area Networks (WLAN), and the popularity of portable devices supporting Wireless Fidelity (Wi-Fi) is continuously growing. At the same time, the number of Active Implanted Medical Devices (AIMD) being placed in patients is widely increasing and among them, cochlear implants (CI) are becoming a common aid. The goal of this study is to investigate the effect on the electromagnetic field distribution and the specific absorption rate (SAR) due to the presence of a CI in a head model during far-field exposure to Wi-Fi frequencies. The head model was obtained by image segmentation, the implant was modelled as a geometric structure, and the exposure sources were modelled as a uniform plane wave (power density = 10 W/m(2)) at 2.4, 5.2 and 5.8 GHz. Vertical and horizontal polarizations were simulated. Conditions with and without CI were compared. The findings of that are: (1) local differences in the field distribution close to the CI, comparing the head models with or without the CI; (2) higher field strength and point SAR value in the cochlear region very close to the CI; (3) negligible differences in the field strength and point SAR value in the cochlear region far from the CI; (4) negligible variations in the average SAR values in the cochlea and head due to the presence of the CI. The results of this study conclude that insertion of a CI brings moderate localized differences in the E, H and point SAR distribution when evaluated close to the electrode array in the cochlea, while negligible differences are found in the average SAR values both in the cochlea and head, independent of frequency and wave polarization.

Effect of a Cochlear Implant on the SAR distribution of the head exposed to 2.4 GHz

Cochlear implants are electronic devices used to restore partial hearing to people with severe hearing impairment. This study aims to evaluate the effects of an external microwave at 2.4 GHz on the SAR distribution inside a head model with a cochlear implant. Results show no harmful effects in the cochlear tissues due to the described interaction.

Modeling and Computation of Electric Potential Field Distribution Generated in Cochlear Tissues by Cochlear Implant Stimulations

Electric potential field distribution induced in the physiological tissues by electrical stimulation through a cochlear implant electrode array, was calculated by modeling the electrical properties of both the human cochlea and the electrode array, using a finite element method. Simulations were done under different stimulation conditions: by considering different electrode configurations and by activating different electrodes along the stimulating array. These parameters were found to affect the resulting field potentials. Results of this study provide a deeper knowledge of the relationship between the stimulation parameters and the actually delivered electric field, which is crucial to develop more efficient and spatially focused excitations of cochlear neural tissues

Analysis of time‐frequency fine structure of transiently evoked otoacoustic emissions to study the effects of exposure to GSM radiofrequency fields

Mobile phones have become very commonly used throughout the world within a short period of time. To date there is only limited knowledge about interaction between electromagnetic fields (EMFs) emitted by mobile phones and the auditory function. Moreover, there is widespread concern that there may be potential for harm. The aim of this study, performed in the framework of the European Commission Project GUARD “Potential adverse effects of GSM cellular phones on hearing” (5FP, QLK4‐CT‐2001‐00150, 2002‐2004), was to assess potential subtle changes in cochlear function of normal hearing subjects by measuring the time‐frequency fine structure of TEOAEs after exposure to low‐intensity EMFs emitted by GSM mobile phones. TEOAEs were recorded in 27 healthy young adults before and after 10 min of real or sham exposure in a double‐blind design. TEOAE data were analyzed both globally (broadband analysis) and using the wavelet transform (analysis of time‐frequency fine structure). The broadband analysis revealed no si...

Measurements of Generated Potentials by the Electrodes of a Cochlear Implant

In this paper it is described the design and development of an experimental setup to measure in-vitro electric potential distribution delivered by a multichannel cochlear implant varying conditions and parameter of usage. In particular, it was studied the spatial distribution of the electric potential released by this implant. To accomplish this task, an automated process of measurement was built to measure the electric potential inside a tank that resembled the typical environment in which the implant is used in real conditions. This study enables a better comprehension of relationship between parameters of stimulations and the electric potential delivered by the cochlear implant, this is fundamental to develop a more efficient and spatially localized stimulation of the nervous tissues.

Experimental Measurements of Potentials Generated by the Electrodes of a Cochlear Implant in a Phantom

The design and development of an experimental setup to measure in-vitro electric potential distribution deliv- ered by a multichannel cochlear implant varying conditions and parameter of usage is described, with particular attention to the spatial distribution of the electric potential generated by this implant. This study enables a better comprehension of the relationships between parameters of stimulations and the electric potential delivered by the cochlear implant, fundamen- tal to develop a more efficient and spatially localized stimula- tion of the nervous tissues.