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A test of a mechanism of simultaneous suppression of tone burst evoked otoacoustic emissions
No full textCurrent theory of transient evoked otoacoustic emission (TEOAE) generation states that TEOAEs recorded using conventional time-windowing techniques arise via randomly distributed, “place-fixed” perturbations in cochlear mechanics. Place-fixed generation is consistent with the widely supported concept of local TEOAE generator channels tonotopically distributed along the basilar membrane (BM), within which a TEOAE component at frequency f, is evoked by a stimulus component at f. This one-to-one relationship between stimulus and TEOAE frequency components underpins the potential for using TEOAEs as a frequency specific measure of cochlear function. Inconsistent with the concept of local TEOAE generator channels, suppression of tone burst evoked otoacoustic emissions caused by the simultaneous presence of additional equi-level, higher frequency tone bursts has been reported, i.e. simultaneous suppression of tone burst evoked otoacoustic emissions (e.g. Yoshikawa et al, 2000). These results implicate a widespread TEOAE generation mechanism wherein a TEOAE component at f is generated at remote BM locations basal to f. This apparent breakdown in correspondence between stimulus and TEOAE components contradicts the use of TEOAEs as a frequency specific measure of cochlear function. However, it has been argued that this suppression phenomenon does not negate the existence of local TEOAE generator channels, but simply indicates the broad spread of BM excitation associated with tone bursts (Killan and Kapadia, 2006). In order to test this theory a simple model based solely on local TEOAE generator channels was developed and used to repeat the methodology employed by Yoshikawa et al (2000) for an extended range of tone burst frequencies (0.5, 1, 1.5, 2, 3 kHz) and levels (40, 50, 60, 70 dB p.e. SPL). Model predictions of suppression were compared to corresponding TEOAE suppression measurements from 14 normally hearing human ears. Results demonstrated that the model was able to make reasonable predictions of the suppression measurements obtained from human ears. However, the model demonstrated a tendency to understimate suppression for conditions when tone bursts were well separated in frequency. Results suggest that local TEOAE generation can account for simultaneous suppression of tone burst evoked otoacoustic emissions and therefore support the use of TEOAEs as a frequency specific assessment of cochlear function. References Killan E.C. & Kapadia S. 2006. Simultaneous suppression of tone burst-evoked otoacoustic emissions – Effect of level and presentation paradigm. Hear Res, 212, 65-73. Yoshikawa H., Smurzynski J. & Probst R. 2000. Suppression of tone burst evoked otoacoustic emissions in relation to frequency separation. Hear Res, 148, 95-106
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Simultaneous suppression of tone burst-evoked otoacoustic emissions for two- and three-tone burst combinations.
Get PDFA tone burst-evoked otoacoustic emission (TBOAE) can be suppressed by the simultaneous presentation of an additional higher frequency tone burst (Yoshikawa et al, 2000; Killan et al, 2012). This simultaneous suppression of TBOAEs (SSTBOAEs) has been explained in terms of a local nonlinear interaction (LNI)-based mechanism (Killan et al, 2012). This states that SSTBOAEs results from local interactions between the basilar membrane vibration patterns caused by each tone burst. These interactions are assumed to be governed by the compressive amplitude nonlinearity exhibited by the TBOAE response. However, there is doubt whether this mechanism can account for SSTBOAEs caused by two additional higher frequency tone bursts. Whilst a simple additive effect is predicted by the LNI-based mechanism (so that more suppression is caused by the three-tone burst combination compared to the two-tone burst combination), comparison of suppression values reported across three separate studies suggests that the opposite is true. There are two possible explanations for this difference: (i) it simply reflects methodological and subject differences across the three studies (none of which tested both two- and three-tone burst combinations), or (ii) it implies that more complex interactions, different to those assumed in the LNI-based mechanism, are involved for the three-tone burst combination. In order to understand which of these alternatives is most likely, SSTBOAEs was measured for two and three-tone burst combinations from thirteen normal ears. Prior to this, predictions were obtained from a model of the LNI-based mechanism described by Killan et al (2012). Model predictions and TBOAE measurements were made that allowed suppression to be calculated (in the region of 1 kHz) for combinations of tone bursts with centre frequencies of 1 and 2 kHz, 1 and 3 kHz and 1, 2 and 3 kHz. Model predictions confirmed the additive suppression effect expected with the LNI-based mechanism, with the three-tone burst combination causing greater suppression than the two-tone burst combination. Comparison of SSTBOAEs across two and three-tone burst combinations revealed a similar additive suppression effect. It is therefore concluded that SSTBOAEs caused by three-tone burst combinations is governed by the same LNI-based mechanism used to account for two-tone burst suppression. The differences apparent across previous studies were most likely accounted for by methodological and subject differences
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Letter to Editor re: "Behavioural Audiometry: Protocol for Measuring Hearing Thresholds in Babies Aged 4-18 Months"
No full textAppropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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