Mobile phones: A trade-off between speech intelligibility and exposure to noise levels and to radio-frequency electromagnetic fields.

When making phone calls, cellphone and smartphone users are exposed to radio-frequency (RF) electromagnetic fields (EMFs) and sound pressure simultaneously. Speech intelligibility during mobile phone calls is related to the sound pressure level of speech relative to potential background sounds and also to the RF-EMF exposure, since the signal quality is correlated with the RF-EMF strength. Additionally, speech intelligibility, sound pressure level, and exposure to RF-EMFs are dependent on how the call is made (on speaker, held at the ear, or with headsets). The relationship between speech intelligibility, sound exposure, and exposure to RF-EMFs is determined in this study. To this aim, the transmitted RF-EMF power was recorded during phone calls made by 53 subjects in three different, controlled exposure scenarios: calling with the phone at the ear, calling in speaker-mode, and calling with a headset. This emitted power is directly proportional to the exposure to RF EMFs and is translated into specific absorption rate using numerical simulations. Simultaneously, sound pressure levels have been recorded and speech intelligibility has been assessed during each phone call. The results show that exposure to RF-EMFs, quantified as the specific absorption in the head, will be reduced when speaker-mode or a headset is used, in comparison to calling next to the ear. Additionally, personal exposure to sound pressure is also found to be highest in the condition where the phone is held next to the ear. On the other hand, speech perception is found to be the best when calling with a phone next to the ear in comparison to the other studied conditions, when background noise is present.

Short-term auditory effects of listening to an MP3 player.

OBJECTIVES: To determine the output levels of a commercially available MPEG layer-3 (MP3) player and to evaluate changes in hearing after 1 hour of listening to the MP3 player. DESIGN: First, A-weighted sound pressure levels (measured in decibels [dBA]) for 1 hour of pop-rock music on an MP3 player were measured on a head and torso simulator. Second, after participants listened to 1 hour of pop-rock music using an MP3 player, changes in hearing were evaluated with pure-tone audiometry, transient-evoked otoacoustic emissions, and distortion product otoacoustic emissions. PARTICIPANTS: Twenty-one participants were exposed to pop-rock music in 6 different sessions using 2 types of headphones at multiple preset gain settings of the MP3 player. MAIN OUTCOME MEASURES: Output levels of an MP3 player and temporary threshold and emission shifts after 1 hour of listening. RESULTS: The output levels at the full gain setting were 97.36 dBA and 102.56 dBA for the supra-aural headphones and stock earbuds, respectively. In the noise exposure group, significant changes in hearing thresholds and transient-evoked otoacoustic emission amplitudes were found between preexposure and postexposure measurements. However, this pattern was not seen for distortion product otoacoustic emission amplitudes. Significant differences in the incidence of significant threshold or emission shifts were observed between almost every session of the noise exposure group compared with the control group. CONCLUSIONS: Temporary changes in hearing sensitivity measured by audiometry and otoacoustic emissions indicate the potential harmful effects of listening to an MP3 player. Further research is needed to evaluate the long-term risk of cumulative noise exposure on the auditory system of adolescents and adults.

The clinical value of the multiple-frequency 80-Hz auditory steady-state response in adults with normal hearing and hearing loss.

OBJECTIVES: To determine the ability of the air-conduction multiple-frequency auditory steady-state response (ASSR) technique to diagnose normal hearing (NH) and mild and moderate degrees of sensorineural hearing loss (SNHL), to assess patients with conductive hearing loss (CHL), to evaluate flat and sloping configurations of hearing impairment, and to provide sensitivity and specificity values for various ASSR cutoff criteria. DESIGN: A comparative study between ASSR and criterion-standard behavioral thresholds. SETTING: Ear, nose, and throat department at a university hospital. PATIENTS: The study population comprised 40 adults with NH, 17 with SNHL, and 7 with CHL. MAIN OUTCOME MEASURES: The measure of interest was the difference between ASSR and behavioral thresholds at 0.5, 1.0, 2.0, and 4.0 kHz. The sensitivity, specificity, positive predictive value, negative predictive value, and efficiency were calculated for several ASSR cutoff criteria. RESULTS: The ASSR technique clearly distinguished moderate SNHL from NH, but the "mild SNHL and NH" and "mild SNHL and moderate SNHL" differentiation was particularly difficult at 0.5 and 2.0 kHz, respectively. Air-conduction ASSR thresholds accurately predicted behavioral thresholds in CHL. The ASSR system precisely reflected the flat and sloping configurations. Finally, the most appropriate ASSR cutoff point for normality seems to be the 30-dB-or-lower criterion. CONCLUSIONS: In adults, the multiple-frequency 80-Hz ASSR technique can be used to determine the degree and configuration of hearing loss. Although air-conduction ASSR thresholds accurately predicted behavioral thresholds in CHL, future research with bone-conduction ASSRs is necessary to establish the type of hearing loss. Furthermore, the applicability of these findings still needs to be confirmed for infants.

Impact of newborn hearing screening: comparing outcomes in pediatric cochlear implant users.

OBJECTIVES/HYPOTHESIS: To evaluate the impact of a newborn hearing screening program on the management and outcome of deaf children and to identify underlying factors that may be responsible for the differences between high and low performing implanted children. STUDY DESIGN: Retrospective cohort study of 391 implanted children in Flanders (Belgium). METHODS: First, implanted children were sorted into two groups on account of screening age (early screened, n = 195 vs. late screened, n = 196). Both groups were compared with respect to several variables. Second, outcome of cochlear implantation was measured in terms of the child's speech perception and production skills (n = 355). A subgroup of high performing cochlear implant (CI) users was compared with low performing CI users with regard to several variables. RESULTS: Early screened children differ significantly from late screened children with respect to age of hearing loss detection and age at cochlear implantation. Furthermore, early screening and implantation is associated with better auditory receptive skills and speech intelligibility. Additional impairments negatively influence both receptive and productive skills. In addition, children who communicate orally and wear bilateral cochlear implants perform better on speech production, whereas a better speech perception was found in children who became progressively deaf as opposed to congenitally deaf children. CONCLUSIONS: The results of this extensive study of profoundly deaf children with CIs in Flanders indicate that a newborn hearing screening program results in earlier intervention in deaf children, which beneficially influences the auditory receptive skills and speech intelligibility.