InSPECtor: an end-to-end design framework for compressive pixelated hyperspectral instruments.

Classic designs of hyperspectral instrumentation densely sample the spatial and spectral information of the scene of interest. Data may be compressed after the acquisition. In this paper, we introduce a framework for the design of an optimized, micropatterned snapshot hyperspectral imager that acquires an optimized subset of the spatial and spectral information in the scene. The data is thereby already compressed at the sensor level but can be restored to the full hyperspectral data cube by the jointly optimized reconstructor. This framework is implemented with TensorFlow and makes use of its automatic differentiation for the joint optimization of the layout of the micropatterned filter array as well as the reconstructor. We explore the achievable compression ratio for different numbers of filter passbands, number of scanning frames, and filter layouts using data collected by the Hyperscout instrument. We show resulting instrument designs that take snapshot measurements without losing significant information while reducing the data volume, acquisition time, or detector space by a factor of 40 as compared to classic, dense sampling. The joint optimization of a compressive hyperspectral imager design and the accompanying reconstructor provides an avenue to substantially reduce the data volume from hyperspectral imagers.

Vector-apodizing phase plate coronagraph: design, current performance, and future development [Invited].

Over the last decade, the vector-apodizing phase plate (vAPP) coronagraph has been developed from concept to on-sky application in many high-contrast imaging systems on 8 m class telescopes. The vAPP is a geometric-phase patterned coronagraph that is inherently broadband, and its manufacturing is enabled only by direct-write technology for liquid-crystal patterns. The vAPP generates two coronagraphic point spread functions (PSFs) that cancel starlight on opposite sides of the PSF and have opposite circular polarization states. The efficiency, that is, the amount of light in these PSFs, depends on the retardance offset from a half-wave of the liquid-crystal retarder. Using different liquid-crystal recipes to tune the retardance, different vAPPs operate with high efficiencies (${\gt}96\%$) in the visible and thermal infrared (0.55 µm to 5 µm). Since 2015, seven vAPPs have been installed in a total of six different instruments, including Magellan/MagAO, Magellan/MagAO-X, Subaru/SCExAO, and LBT/LMIRcam. Using two integral field spectrographs installed on the latter two instruments, these vAPPs can provide low-resolution spectra (${\rm{R}} \sim 30$) between 1 µm and 5 µm. We review the design process, development, commissioning, on-sky performance, and first scientific results of all commissioned vAPPs. We report on the lessons learned and conclude with perspectives for future developments and applications.

LOUPE: observing Earth from the Moon to prepare for detecting life on Earth-like exoplanets.

LOUPE, the Lunar Observatory for Unresolved Polarimetry of the Earth, is a small, robust spectro-polarimeter for observing the Earth as an exoplanet. Detecting Earth-like planets in stellar habitable zones is one of the key challenges of modern exoplanetary science. Characterizing such planets and searching for traces of life requires the direct detection of their signals. LOUPE provides unique spectral flux and polarization data of sunlight reflected by Earth, the only planet known to harbour life. These data will be used to test numerical codes to predict signals of Earth-like exoplanets, to test algorithms that retrieve planet properties, and to fine-tune the design and observational strategies of future space observatories. From the Moon, LOUPE will continuously see the entire Earth, enabling it to monitor the signal changes due to the planet's daily rotation, weather patterns and seasons, across all phase angles. Here, we present both the science case and the technology behind LOUPE's instrumental and mission design. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades'.

Design trade-off and proof of concept for LOUPE, the Lunar Observatory for Unresolved Polarimetry of Earth.

We provide a proof of the technical feasibility of LOUPE, the first integral-field snapshot spectropolarimeter, designed to monitor the reflected flux and polarization spectrum of Earth. These are to be used as benchmark data for the retrieval of biomarkers and atmospheric and surface characteristics from future direct observations of exoplanets. We perform a design trade-off for an implementation in which LOUPE performs snapshot integral-field spectropolarimetry at visible wavelengths. We used off-the-shelf optics to construct a polarization modulator, in which polarization information is encoded into the spectrum as a wavelength-dependent modulation, while spatial resolution is maintained using a micro-lens array. The performance of this design concept is validated in a laboratory setup. Our proof-of-concept is capable of measuring a grid of 50 × 50 polarization spectra between 610 and 780 nm of a mock target planet - proving the merit of this design. The measurements are affected by systematic noise on the percent level, and we discuss how to mitigate this in future iterations. We conclude that LOUPE can be small and robust while meeting the science goals of this particular space application, and note the many potential applications that may benefit from our concept for doing snapshot integral-field spectropolarimetry.

Fitting range of the BAHA Intenso.

Audiometric characteristics of a recently introduced more powerful, behind-the-ear, BAHA sound processor, the BAHA Intenso, were evaluated in 23 patients with contra-indications for using conventional hearing aids. All patients had mixed hearing loss with boneconduction thresholds ranging between 30 and 50 dB HL. Boneconduction gain, defined as the difference in aided free-field detection thresholds and unaided boneconduction thresholds, was calculated at the octave frequencies between 500 Hz and 4 kHz. Median boneconduction gain of the Intenso ranges from 0 dB at 500 ;Hz to 12 ;dB at 2 kHz with substantial interindividual variability. The upper limit of the BAHA Intenso's fitting range was established by requiring aided speech reception thresholds with CVC-monosyllables of at most 60 dB SPL. The fitting range of the BAHA Intenso appeared to be limited to 42, 44, 58, and 48 dB HL for boneconduction thresholds at 0.5, 1, 2, and 4 ;kHz, respectively. Loudness growth functions at 0.5 and 3 kHz as obtained with 7-point categorical scaling showed an adequate aided dynamic range.

The effect of the "floating mass transducer" in the middle ear on hearing sensitivity.

OBJECTIVE: The Vibrant soundbridge is a semi-implantable hearing device; the transducer is implanted, coupled directly to the incus. The influence of the implant surgery and the presence of the transducer on hearing sensitivity was studied in six implanted subjects. STUDY DESIGN: Longitudinal case reports. SETTING: Tertiary referral center. Subjects. The subjects had bilateral sensorineural hearing loss with an average hearing loss of 40 to 70 dB HL. RESULTS: In five of the six subjects, no long-term effect of the surgery or the presence of the transducer on hearing thresholds was found. In the remaining subject, a deterioration in hearing thresholds was found of 20 dB, with a high and low frequency component. In the 2-kHz region, hearing sensitivity was not deteriorated. In addition, chronic negative middle ear pressure occurred after surgery. CONCLUSION: Hearing thresholds did not change significantly in five of the six patients after placement of the "floating mass transducer." It was speculated that the high frequency component of the hearing deterioration in the remaining patient was caused by cochlear damage caused by the surgery and that the low frequency component was caused by the chronic aeration problems indirectly related to the surgery.

Cochlear implantation in deaf children.

A cochlear implant (CI) is a hearing device introduced in the 1980s for profoundly deaf subjects who gained little or no benefit from powerful hearing aids. This device comprises an electrode array inserted in the cochlea, connected to an internal receiver, and an externally worn speech processor. The CI transforms acoustic signals into electrical currents which directly stimulate the auditory nerve. Since the early 1990s, cochlear implantation in children has been developing rapidly. Although it is still difficult to predict how a child will perform with a cochlear implant, the success of cochlear implantation can no longer be denied. In this paper, some recent papers and reports, and the results of the various Nijmegen cochlear implant studies, are reviewed. Issues about selection, examinations, surgery and the outcome are discussed. Overall, our results were comparable with those of other authors. It can be concluded that cochlear implantation is an effective treatment for postlingually deaf as well as prelingually (congenital or acquired) deaf children with profound bilateral sensorineural deafness.

Noninvasive assessment of the intralabyrinthine pressure. A new technique applied to patients with X-linked progressive mixed deafness syndrome with perilymphatic gusher during stapes surgery.

In this report, we describe the findings of a noninvasive assessment of the intralabyrinthine pressure in two patients from a family with X-linked progressive, mixed deafness syndrome in whom a perilymphatic gusher occurs during stapes surgery. The so-called tympanic membrane displacement measurement technique could be successfully applied in these two patients (from a total of five patients who were studied) because they still showed a stapedial reflex at 1 kHz, which is mandatory for application of the tympanic membrane displacement measurement technique. The findings were compared with those of age-related control subjects and indicated a significantly elevated intralabyrinthine pressure in the two patients who were observed. The results suggest that the tympanic membrane displacement measurement technique may serve as a screening test in audiological diagnostic studies of perilymphatic hypertension.

Speech recognition in patients after successful surgery for unilateral congenital ear anomalies.

It is generally assumed that auditory stimulation since birth is important for the proper development of the central auditory nervous system. Whether auditory deprivation occurs in man and, therefore, whether it may be considered as a contraindication to surgery in unilateral congenital middle ear anomalies and atresias is the subject of the present study. Speech recognition during both monaural and binaural presentation was studied in patients who had successful surgery for a unilateral congenital ear anomaly. In binaural speech recognition tests, the average results of the patient group (N = 13) and a group of subjects with normal hearing proved to be comparable. The average speech recognition score using monaurally presented band-pass filtered speech was 84% +/- 8% and 77% +/- 10% for the unoperated (normal) and operated ears, respectively (statistically significant). Speech-to-noise ratios of -5.6 +/- 0.7 dB and -3.9 +/- 1.6 db were found in the normal and operated ears, respectively (statistically significant). It is concluded that, in general, the speech recognition scores of the operated ears were satisfactory, but poorer than those of the normal ears.

Audiological results of the bone-anchored hearing aid HC200: multicenter results.

Sixty-two patients with conductive or mixed hearing loss (average bone conduction threshold at 0.5, 1, and 2 kHz ranged from 1 to 44 dB hearing level) were fitted with a bone-anchored hearing aid (BAHA type HC200). Previously, 52 of them had used a conventional bone conduction hearing aid (CBHA) and 10 of them an air conduction hearing aid (ACHA). Audiological tests were conducted to compare the patients' performance with the BAHA to that with their previous conventional hearing aid. In the speech recognition in quiet test, only 5 patients in the CBHA group improved significantly: the majority had 100% scores with both hearing aids. In the speech recognition in noise test, 28 patients improved significantly. The mean improvement in the signal to noise ratio (S/N) in the CBHA group was -2.3 +/- 2.4 dB. That none of the patients in the CBHA group performed worse with the BAHA led us to the conclusion that the BAHA is superior to the CBHA. None of the patients in the ACHA group achieved a better speech recognition in quiet score using the BAHA. On average, there was no significant improvement in the S/N ratio in the ACHA group, although in 6 patients the S/N ratio improved significantly, and in 1 patient it worsened significantly. From the whole group, the performance of only 2 patients, both in the ACHA group, was significantly worse with the BAHA on one of the speech recognition tests.

Hearing with the bone-anchored hearing aid (BAHA, HC 200) compared to a conventional bone-conduction hearing aid.

Sixteen patients have been fitted with a standard bone-anchored hearing aid (HC 200), to replace their conventional bone-conduction aid. The average pure tone threshold at 0.5, 1 and 2 kHz varied from 35 to 75 dB HL, with a sensorineural component varying from 0 to 30 dB HL. The patients' performance with the bone-anchored aid was compared to that with the conventional bone-conduction aid in an acoustic-free field. The maximum phoneme score in quiet was 100% in most patients; in 6 patients, the score with the bone-anchored aid was better (range from 5 to 10%). The speech-in-noise ratio was significantly better in 11 patients (range from -1.4 to -8 dB). None of the patients had poorer results on either test with the bone-anchored aid. The improved speech recognition was ascribed to better performance of the hearing aid in the higher frequency range (above 2 kHz) and to relatively less distortion.