72 research outputs found

    The just-noticeable difference in speech-to-noise ratio

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    Just-noticeable differences (JNDs) have been measured for various features of sounds, but despite its importance to communication, there is no benchmark for what is a just-noticeable—and possibly meaningful—difference in speech-to-noise ratio (SNR). SNR plays a crucial role in speech communication for normal-hearing and hearing-impaired listeners. Difficulty hearing speech in background noise—a poor SNR—often leads to dissatisfaction with hearing-assistance devices. While such devices attempt through various strategies to address this problem, it is not currently known how much improvement in SNR is needed to provide a noticeable benefit. To investigate what is a noticeable benefit, we measured the JND in SNR for both normal-hearing and hearing-impaired listeners. Here, we report the SNR JNDs of 69 participants of varying hearing ability, estimated using either an adaptive or fixed-level procedure. The task was to judge which of the two intervals containing a sentence in speech-spectrum noise presented over headphones was clearer. The level of each interval was roved to reduce the influence of absolute level cues. The results of both procedures showed an average SNR JND of 3 dB that was independent of hearing ability. Further experiments using a subset of normal-hearing listeners showed that level roving does elevate threshold. These results suggest that noise reduction schemes may need to achieve a benefit greater than 3 dB to be reliably discriminable

    The just meaningful difference in speech-to-noise ratio

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    The speech-to-noise ratio (SNR) in an environment plays a vital role in speech communication for both normal-hearing (NH) and hearing-impaired (HI) listeners. While hearing-assistance devices attempt to deliver as favorable an SNR as possible, there may be discrepancies between noticeable and meaningful improvements in SNR. Furthermore, it is not clear how much of an SNR improvement is necessary to induce intervention-seeking behavior. Here we report on a series of experiments examining the just-meaningful difference (JMD) in SNR. All experiments used sentences in same-spectrum noise, with two intervals on each trial mimicking examples of pre- and post-benefit situations. Different groups of NH and HI adults were asked (a) to rate how much better or worse the change in SNR was in a number of paired examples, (b) if they would swap the worse for the better SNR (e.g., their current device for another) or (c) if they would be willing to go to the clinic for the given increase in SNR. The mean SNR JMD based on better/worse ratings (one arbitrary unit) was similar to the just-noticeable difference, approximately 3 dB. However, the mean SNR JMD for the more clinically relevant tasks -- willingness (at least 50% of the time) to swap devices or attend the clinic for a change in SNR -- was 6-8 dB regardless of hearing ability. This SNR JMD of the order of 6 dB provides a new benchmark, indicating the SNR improvement necessary to immediately motivate participants to seek intervention

    Natural variation in stomata size contributes to the local adaptation of water-use efficiency in Arabidopsis thaliana

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    Stomata control gas exchanges between the plant and the atmosphere. How natural variation in stomata size and density contributes to resolve trade-offs between carbon uptake and water loss in response to local climatic variation is not yet understood. We developed an automated confocal microscopy approach to characterize natural genetic variation in stomatal patterning in 330 fully sequenced Arabidopsis thaliana accessions collected throughout the European range of the species. We compared this to variation in water-use efficiency, measured as carbon isotope discrimination (C-13). We detect substantial genetic variation for stomata size and density segregating within Arabidopsis thaliana. A positive correlation between stomata size and C-13 further suggests that this variation has consequences on water-use efficiency. Genome wide association analyses indicate a complex genetic architecture underlying not only variation in stomatal patterning but also to its covariation with carbon uptake parameters. Yet, we report two novel QTL affecting C-13 independently of stomatal patterning. This suggests that, in A. thaliana, both morphological and physiological variants contribute to genetic variance in water-use efficiency. Patterns of regional differentiation and covariation with climatic parameters indicate that natural selection has contributed to shape some of this variation, especially in Southern Sweden, where water availability is more limited in spring relative to summer. These conditions are expected to favour the evolution of drought avoidance mechanisms over drought escape strategies

    Survey of highly non-Keplerian orbits with low-thrust propulsion

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    Celestial mechanics has traditionally been concerned with orbital motion under the action of a conservative gravitational potential. In particular, the inverse square gravitational force due to the potential of a uniform, spherical mass leads to a family of conic section orbits, as determined by Isaac Newton, who showed that Kepler‟s laws were derivable from his theory of gravitation. While orbital motion under the action of a conservative gravitational potential leads to an array of problems with often complex and interesting solutions, the addition of non-conservative forces offers new avenues of investigation. In particular, non-conservative forces lead to a rich diversity of problems associated with the existence, stability and control of families of highly non-Keplerian orbits generated by a gravitational potential and a non-conservative force. Highly non-Keplerian orbits can potentially have a broad range of practical applications across a number of different disciplines. This review aims to summarize the combined wealth of literature concerned with the dynamics, stability and control of highly non-Keplerian orbits for various low thrust propulsion devices, and to demonstrate some of these potential applications

    Bewertung epithelialer Veränderungen des Kehlkopfes mittels konfokaler Laserendomikroskopie

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    Hintergrund: Die Confocale Laser Endomikroskopie (CLE) ermöglicht eine "Echtzeit-Biopsie" des Epithels im oberen Aerodigestivtrakt. Durch die 1.000-fache Vergrößerung entsprechen die gewonnenen Bilder konventionellen histologischen Schnittbildern. Der Unterschied besteht darin, dass bei der CLE keine Gewebsverletzung entsteht. Es ist bekannt, dass an den Stimmlippen schon geringste invasive Maßnahmen das Risiko einer dauerhaften Schädigung der Stimmqualität bergen können. Die CLE scheint besonders geeignet, non-invasiv eine strukturelle Untersuchung des Epithels des Kehlkopfes vorzunehmen. Ziel dieser Studie war der Nachweis, dass mittels CLE Neubildungen der Larynxschleimhaut von gesundem Epithel differenziert werden können.Material und Methoden: Bei 10 Mikrolaryngoendoskopien wurden mit der "GastroFlex UHD Sonde" (Cellvizio, Mauna Kea Technologies, Paris) Aufnahmen des Larynxepithels durchgeführt. Benigne und maligne Veränderungen der Stimmlippen sowie klinisch gesunde Schleimhaut wurden aufgezeichnet. Zur Verifizierung der Befunde wurden von den Raumforderungen Biopsien entnommen. Die Auswertung der CLE-Aufnahmen erfolgte verblindet durch einen mit der Methode vertrauten HNO-Arzt und einen erfahrenen Pathologen, sowie durch methodisch unerfahrene HNO-Ärzte.Ergebnisse: Ihm Rahmen der Bewertung der CLE-Sequenzen waren alle Untersucher in der Lage, an Hand der Regularität des epithelialen Stomas und der Form der Epithelzellen mit einer hohen Ratewahrscheinlichkeit gesundes Epithel von den Raumforderungen zu unterscheiden. Der erfahrene HNO-Arzt und der Pathologe waren zudem in der Lage, in einem hohen Maß die bösartigen Veränderungen von den gutartigen Läsionen zu unterscheiden.Fazit: Die CLE ist ein geeignetes nicht-invasives Verfahren zur "echtzeit" Diagnostik von Erkrankungen des Stimmlippenepithels. Die Bewertung ist subjektiv und abhängig von der Erfahrung des Untersuchers. Die Bewertungskriterien entsprechen denen der Beurteilung von nativen histologischen Präparaten

    Rezidivierende lageabhängige Drehschwindelanfälle, kann das BPLS sein?

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    Learning hearing aid

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    A new hearing aid system is provided that includes geographical position and user feedback in determining the category of the sound environment for automatic adjustment of signal processing parameters

    Et positionslærende høreapparat

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    A new hearing aid system is provided that includes geographical position and user feedback in determining the category of the sound environment for automatic adjustment of signal processing parameters
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