The use of a SQUID magnetometer for middle ear research

A new technique is described for the measurement of vibrations in the temporal bones of an isolated middle ear. The precise recording of vibrations in the middle ear is of importance for the construction and improvement of a middle ear prosthesis.1 The method of measurement is based on a transformation of mechanical vibrations into magnetic flux variations. This is performed by attaching a small piece of permanent magnetic material to the eardrum or middle ear ossicles. The magnetic flux variations caused by vibrations of the eardrum or ossicles during application of sound can be measured by means of a SQUID magnetometer.\ud \ud Measurements showed that it is possible to measure vibratory displacement amplitudes of the eardrum down to about 10−10 m in a frequency range between 200 Hz and 10 kHz, although the acoustical and magnetometer conditions were not optimal. The method offers several advantages compared to already existing methods.2–5,

Electronic dummy for acoustical testing

Electronic Dummy /ED/ used for acoustical testing represents the average male torso from the Xiphoid process upward and includes an acoustic replica of the human head. This head simulates natural flesh, and has an artificial voice and artificial ears that measure sound pressures at the eardrum or the entrance to the ear canal

The iso-response method

Throughout the nervous system, neurons integrate high-dimensional input streams and transform them into an output of their own. This integration of incoming signals involves filtering processes and complex non-linear operations. The shapes of these filters and non-linearities determine the computational features of single neurons and their functional roles within larger networks. A detailed characterization of signal integration is thus a central ingredient to understanding information processing in neural circuits. Conventional methods for measuring single-neuron response properties, such as reverse correlation, however, are often limited by the implicit assumption that stimulus integration occurs in a linear fashion. Here, we review a conceptual and experimental alternative that is based on exploring the space of those sensory stimuli that result in the same neural output. As demonstrated by recent results in the auditory and visual system, such iso-response stimuli can be used to identify the non-linearities relevant for stimulus integration, disentangle consecutive neural processing steps, and determine their characteristics with unprecedented precision. Automated closed-loop experiments are crucial for this advance, allowing rapid search strategies for identifying iso-response stimuli during experiments. Prime targets for the method are feed-forward neural signaling chains in sensory systems, but the method has also been successfully applied to feedback systems. Depending on the specific question, “iso-response” may refer to a predefined firing rate, single-spike probability, first-spike latency, or other output measures. Examples from different studies show that substantial progress in understanding neural dynamics and coding can be achieved once rapid online data analysis and stimulus generation, adaptive sampling, and computational modeling are tightly integrated into experiments

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

Hearing health outreach services to Indigenous children and young people in the Northern Territory 2012–13 and 2013–14

Presents analyses on hearing health outreach services provided to Indigenous children and young people in the Northern Territory. Summary This report presents information on ear and hearing outreach services funded by the Department of Health and delivered by the Northern Territory Department of Health between July 2012 and June 2014. The main funding sources for these services are the National Partnership Agreement on Stronger Futures in the Northern Territory and the Healthy Ears—Better Hearing, Better Listening program. The report also includes information on hearing health and middle ear conditions among service recipients. Service delivery In 2013–14, 2,122 outreach audiology services were delivered to 1,764 Indigenous children and young people. In total, from July 2012 to June 2014, 4,054 audiology services were delivered to 2,889 children and young people. Child Hearing Health Coordinators (CHHCs) conducted 697 visits to 675 children in 2013–14—slightly below the target of 700 children set by the Australian and Northern Territory governments. In total, 1,140 children were seen at 1,208 CHHC visits from July 2012 to June 2014. A total of 860 ear, nose and throat (ENT) teleotology services were provided to 766 children and young people in 2013–14. From July 2012 to June 2014, 1,684 ENT teleology services were provided to 1,283 children and young people. Hearing health status among children and young people who received services Hearing loss was present in 55% of children and young people who received outreach audiology services at their latest service in 2013–14. Hearing health status improved for a large proportion of the children and young people who received 2 or more outreach audiology services. Of the 498 children and young people who had hearing loss at their first audiology service, 41% experienced functional improvements in their hearing (with 26% regaining normal hearing capability at their last check, and 15% having their hearing loss status improve from bilateral to unilateral). Among 102 children and young people with hearing impairment at their first audiology check, the severity of impairment improved for 50% at their last check, remained at the same level for 40%, and deteriorated for 10%. Middle ear conditions among children and young people who received services In 2013–14, of the 1,791 children and young people who received an audiology or ENT service, 67% were diagnosed with at least 1 type of middle ear condition (an increase from 61% in 2012–13)—most commonly otitis media with effusion (24%). Of the 781 children and young people who received 2 or more ENT or audiology services from July 2012 to June 2014, the proportion diagnosed with at least 1 middle ear condition between the first and last service decreased, from 79% to 76%. Improvements were seen for those who received 3 or more services since August 2007: the proportion of children and young people diagnosed with at least 1 middle ear condition decreased, from 81% at the first service to 55% at the last service. Among those diagnosed with chronic suppurative otitis media with discharge or dry perforation at an initial service, overall, the results suggest poor progress, with the majority of these children and young people still experiencing the same condition or developing another type of ear disease over the course of their treatment