bluuebunny/crossref_metadata_2025 huggingface dataset:
Marker‐free genetic engineering of the chloroplast in the green microalga Chlamydomonas reinhardtii
Authors: Chen Hsu‐Ching , Melis Anastasios
Published: May 2013

The work applied a transgene expression method based on the replacement of an inactive rbcL gene as the selection marker in Chlamydomonas reinhardtii chloroplasts. The native rbcL gene in strain CC2653 has a point mutation that causes early translation termination, thus resulting in a photosynthesis mutant. Recovery of rbcL function for selection is offered along with the heterologous expression of the alcohol dehydrogenase ADH1 gene from Saccharomyces cerevisiae in the Chlamydomonas chloroplast. The CrCpADH1 gene was inserted via double homologous recombination in the psaB‐rbcL chloroplast intergenic region of recipient strain CC2653, using the psaB and rbcL gene sequences for the double homologous recombination. This transformation conferred a functional rbcL gene and expression of the CrCpADH1 transgene in the recipient strain. This method alleviated the need to use antibiotics for selection, resulting in a negligible number of false positives during screening, and attaining a transformation efficiency greater than 90%. The approach also ensured segregation of chloroplast DNA copies, so as to achieve homoplasmy of the transformant chloroplast DNA, with a concomitant elimination of recipient strain Cp DNA. High levels of steady‐state CrCpADH1 transcripts were detected in the homoplasmic transformants. However, CrCpADH1 protein levels were attenuated under continuous illumination growth conditions due to oxygen accumulation in the cells. Under conditions of low oxygen partial pressure, or anoxia, accumulation of CrCpADH1 protein in the cells and ethanol in the growth medium was observed. A metabolic pathway for ethanol production is proposed in Chlamydomonas, mediated by the chloroplast‐localized CrCpADH1 transgenic enzyme.
Adult stem cells for chronic lung diseases
Authors: Mora Ana L. , Rojas Mauricio
Published: May 2013

Idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) are chronic, progressive and lethal lung diseases. The incidence of IPF and COPD increases with age, independent of exposure to common environmental risk factors. At present, there is limited understanding of the relationship between ageing and the development of chronic lung diseases. One hypothesis is that chronic injury drives to exhaustion the local and systemic repair responses in the lung. These changes are accentuated during ageing where there is a progressive accumulation of senescent cells. Recently, stem cells have emerged as a critical reparative mechanism for lung injury. In this review, we discuss the repair response of bone marrow‐derived mesenchymal stem cells (B‐MSC) after lung injury and how their function is affected by ageing. Our own work has demonstrated a protective role of B‐MSC in several animal models of acute and chronic lung injury. We recently demonstrated the association, using animal models, between age and an increase in the susceptibility to develop severe injury and fibrosis. At the same time, we have identified functional differences between B‐MSC isolated from young and old animals. Further studies are required to understand the functional impairment of ageing B‐MSC, ultimately leading to a rapid stem cell depletion or fatigue, interfering with their ability to play a protective role in lung injury. The elucidation of these events will help in the development of rational and new therapeutic strategies for COPD and IPF.
Whey protein hydrolysate augments tendon and muscle hypertrophy independent of resistance exercise contraction mode
Authors: Farup J. , Rahbek S. K. , Vendelbo M. H. , Matzon A. , Hindhede J. , Bejder A. , Ringgard S. , Vissing K.
Published: May 2013

In a comparative study, we investigated the effects of maximal eccentric or concentric resistance training combined with whey protein or placebo on muscle and tendon hypertrophy. 22 subjects were allocated into either a high‐leucine whey protein hydrolysate + carbohydrate group (WHD) or a carbohydrate group (PLA). Subjects completed 12 weeks maximal knee extensor training with one leg using eccentric contractions and the other using concentric contractions. Before and after training cross‐sectional area (CSA) of m. quadriceps and patellar tendon CSA was quantified with magnetic resonance imaging and a isometric strength test was used to assess maximal voluntary contraction (MVC) and rate of force development (RFD). Quadriceps CSA increased by 7.3 ± 1.0% (P < 0.001) in WHD and 3.4 ± 0.8% (P < 0.01) in PLA, with a greater increase in WHD compared to PLA (P < 0.01). Proximal patellar tendon CSA increased by 14.9 ± 3.1% (P < 0.001) and 8.1 ± 3.2% (P = 0.054) for WHD and PLA, respectively, with a greater increase in WHD compared to PLA (P < 0.05), with no effect of contraction mode. MVC and RFD increased by 15.6 ± 3.5% (P < 0.001) and 12–63% (P < 0.05), respectively, with no group or contraction mode effects. In conclusion, high‐leucine whey protein hydrolysate augments muscle and tendon hypertrophy following 12 weeks of resistance training – irrespective of contraction mode.
Cytoskeleton‐dependent endomembrane organization in plant cells: an emerging role for microtubules
Authors: Brandizzi Federica , Wasteneys Geoffrey O.
Published: May 2013

Movement of secretory organelles is a fascinating yet largely mysterious feature of eukaryotic cells. Microtubule‐based endomembrane and organelle motility utilizing the motor proteins dynein and kinesin is commonplace in animal cells. In contrast, it has been long accepted that intracellular motility in plant cells is predominantly driven by myosin motors dragging organelles and endomembrane‐bounded cargo along actin filament bundles. Consistent with this, defects in the acto‐myosin cytoskeleton compromise plant growth and development. Recent findings, however, challenge the actin‐centric view of the motility of critical secretory organelles and distribution of associated protein machinery. In this review, we provide an overview of the current knowledge on actin‐mediated organelle movement within the secretory pathway of plant cells, and report on recent and exciting findings that support a critical role of microtubules in plant cell development, in fine‐tuning the positioning of Golgi stacks, as well as their involvement in cellulose synthesis and auxin polar transport. These emerging aspects of the biology of microtubules highlight adaptations of an ancestral machinery that plants have specifically evolved to support the functioning of the acto‐myosin cytoskeleton, and mark new trends in our global appreciation of the complexity of organelle movement within the plant secretory pathway.
Durational cues to fricative codas in 2-year-olds' American English: Voicing and morphemic factors
Authors: Yung Song Jae , Demuth Katherine , Evans Karen , Shattuck-Hufnagel Stefanie
Published: May 2013

In the process of phonological development, fricatives are generally assumed to be later acquired than stops. However, most of the observational work on which this claim is based has concerned itself with word-initial onset consonants; little is known about how and when fricatives are mastered in word-final coda position (e.g., nose). This is all the more critical in a language like English, where word-final fricatives often carry important morphological information (e.g., toes, goes). This study examines the development of duration cues to the voicing feature contrast in coda fricatives, using longitudinal spontaneous speech data from CVC words (e.g., noise vs face) produced by three children (1;6–2;6 years) and six mothers. Results show that the children were remarkably adult-like in the use of duration cues to voicing contrasts in fricatives even in this early age range. Furthermore the children, like the mothers, had longer frication noise durations for morphemic compared to non-morphemic fricatives (e.g., toes vs nose) when these segments occurred in utterance-final position. These results suggest that although children's fricatives tend to be overall longer and more voiced compared to those of adults, the voicing and morphological contrasts for fricative codas are acquired early in production.
On-line perception of Mandarin Tones 2 and 3: Evidence from eye movements
Authors: Shen Jing , Deutsch Diana , Rayner Keith
Published: May 2013

Using the visual world paradigm, the present study investigated on-line processing of fine-grained pitch information prior to lexical access in a tone language; specifically how lexical tone perception of Mandarin Tones 2 and 3 was influenced by the pitch height of the tone at onset, turning point, and offset. Native speakers of Mandarin listened to manipulated tone tokens and selected the corresponding word from four visually presented words (objects in Experiment 1 and characters in Experiment 2) while their eye movements were monitored. The results showed that 87% of ultimate tone judgments were made according to offset pitch height. Tokens with high offset pitch were identified as Tone 2, and low offset pitch as Tone 3. A low turning point pitch served as a pivotal cue for Tone 3, and prompted more eye fixations on Tone 3 items, until the offset pitch directed significantly more fixations to the final tone choice. The findings support the view that lexical tone perception is an incremental process, in which pitch height at critical points serves as an important cue.
Human interaural time difference thresholds for sine tones: The high-frequency limit
Authors: Brughera Andrew , Dunai Larisa , Hartmann William M.
Published: May 2013

The smallest detectable interaural time difference (ITD) for sine tones was measured for four human listeners to determine the dependence on tone frequency. At low frequencies, 250–700 Hz, threshold ITDs were approximately inversely proportional to tone frequency. At mid-frequencies, 700–1000 Hz, threshold ITDs were smallest. At high frequencies, above 1000 Hz, thresholds increased faster than exponentially with increasing frequency becoming unmeasurably high just above 1400 Hz. A model for ITD detection began with a biophysically based computational model for a medial superior olive (MSO) neuron that produced robust ITD responses up to 1000 Hz, and demonstrated a dramatic reduction in ITD-dependence from 1000 to 1500 Hz. Rate-ITD functions from the MSO model became inputs to binaural display models—both place based and rate-difference based. A place-based, centroid model with a rigid internal threshold reproduced almost all features of the human data. A signal-detection version of this model reproduced the high-frequency divergence but badly underestimated low-frequency thresholds. A rate-difference model incorporating fast contralateral inhibition reproduced the major features of the human threshold data except for the divergence. A combined, hybrid model could reproduce all the threshold data.
Spatial perception of sound fields recorded by spherical microphone arrays with varying spatial resolution
Authors: Avni Amir , Ahrens Jens , Geier Matthias , Spors Sascha , Wierstorf Hagen , Rafaely Boaz
Published: May 2013

The area of sound field synthesis has significantly advanced in the past decade, facilitated by the development of high-quality sound-field capturing and re-synthesis systems. Spherical microphone arrays are among the most recently developed systems for sound field capturing, enabling processing and analysis of three-dimensional sound fields in the spherical harmonics domain. In spite of these developments, a clear relation between sound fields recorded by spherical microphone arrays and their perception with a re-synthesis system has not yet been established, although some relation to scalar measures of spatial perception was recently presented. This paper presents an experimental study of spatial sound perception with the use of a spherical microphone array for sound recording and headphone-based binaural sound synthesis. Sound field analysis and processing is performed in the spherical harmonics domain with the use of head-related transfer functions and simulated enclosed sound fields. The effect of several factors, such as spherical harmonics order, frequency bandwidth, and spatial sampling, are investigated by applying the repertory grid technique to the results of the experiment, forming a clearer relation between sound-field capture with a spherical microphone array and its perception using binaural synthesis regarding space, frequency, and additional artifacts. The experimental study clearly shows that a source will be perceived more spatially sharp and more externalized when represented by a binaural stimuli reconstructed with a higher spherical harmonics order. This effect is apparent from low spherical harmonics orders. Spatial aliasing, as a result of sound field capturing with a finite number of microphones, introduces unpleasant artifacts which increased with the degree of aliasing error.
On the balance of envelope and temporal fine structure in the encoding of speech in the early auditory system
Authors: Shamma Shihab , Lorenzi Christian
Published: May 2013

There is much debate on how the spectrotemporal modulations of speech (or its spectrogram) are encoded in the responses of the auditory nerve, and whether speech intelligibility is best conveyed via the “envelope” (E) or “temporal fine-structure” (TFS) of the neural responses. Wide use of vocoders to resolve this question has commonly assumed that manipulating the amplitude-modulation and frequency-modulation components of the vocoded signal alters the relative importance of E or TFS encoding on the nerve, thus facilitating assessment of their relative importance to intelligibility. Here we argue that this assumption is incorrect, and that the vocoder approach is ineffective in differentially altering the neural E and TFS. In fact, we demonstrate using a simplified model of early auditory processing that both neural E and TFS encode the speech spectrogram with constant and comparable relative effectiveness regardless of the vocoder manipulations. However, we also show that neural TFS cues are less vulnerable than their E counterparts under severe noisy conditions, and hence should play a more prominent role in cochlear stimulation strategies.
Reconstructing surface wave profiles from reflected acoustic pulses
Authors: Walstead Sean P. , Deane Grant B.
Published: May 2013

Surface wave shapes are determined by analyzing underwater reflected acoustic signals. The acoustic signals (of nominal frequency 200 kHz) are forward scattered from the underside of surface waves that are generated in a wave tank and scaled to model smooth ocean swell. An inverse processing algorithm is designed and implemented to reconstruct the surface displacement profiles of the waves over one complete period. The inverse processing uses the surface scattered pulses collected at the receiver, an initial wave profile (two are considered), and a broadband forward scattering model based on Kirchhoff's diffraction formula to iteratively adjust the surface until it is considered optimized or reconstructed. Two physical length scales over which information can be known about the surface are confirmed. An outer length scale, the Fresnel zone surrounding each specular reflection point, is the only region where optimized surfaces resulting from each initial profile converge within a resolution set by the inner length scale, a quarter-wavelength of the acoustic pulse. The statistical confidence of each optimized surface is also highest within a Fresnel zone. Future design considerations are suggested such as an array of receivers that increases the region of surface reconstruction by a factor of 2 to 3.
The function of male sperm whale slow clicks in a high latitude habitat: Communication, echolocation, or prey debilitation?
Authors: Oliveira Cláudia , Wahlberg Magnus , Johnson Mark , Miller Patrick J. O. , Madsen Peter T.
Published: May 2013

Sperm whales produce different click types for echolocation and communication. Usual clicks and buzzes appear to be used primarily in foraging while codas are thought to function in social communication. The function of slow clicks is less clear, but they appear to be produced by males at higher latitudes, where they primarily forage solitarily, and on the breeding grounds, where they roam between groups of females. Here the behavioral context in which these vocalizations are produced and the function they may serve was investigated. Ninety-nine hours of acoustic and diving data were analyzed from sound recording tags on six male sperm whales in Northern Norway. The 755 slow clicks detected were produced by tagged animals at the surface (52%), ascending from a dive (37%), and during the bottom phase (11%), but never during the descent. Slow clicks were not associated with the production of buzzes, other echolocation clicks, or fast maneuvering that would indicate foraging. Some slow clicks were emitted in seemingly repetitive temporal patterns supporting the hypothesis that the function for slow clicks on the feeding grounds is long range communication between males, possibly relaying information about individual identity or behavioral states.
Per-survivor processing for underwater acoustic communications with direct-sequence spread spectrum
Authors: Xu Xiaoka , Zhou Shengli , Morozov Andrey K. , Preisig James C.
Published: May 2013

This paper proposes a receiver for direct-sequence spread spectrum transmissions in underwater acoustic channels, which combines a per-survivor processing (PSP) structure with sparse channel estimation. Specifically, the PSP structure establishes the trellis on the symbol level to render a small to moderate number of states, thus reducing the computational complexity. Meanwhile, the sparse channel estimation is performed on the chip level, where the orthogonal matching pursuit algorithm is used and a two-dimensional grid of path delay and Doppler scaling factor is incorporated in the dictionary construction. The effective combination of the PSP detection and sparse channel estimation achieves a good tradeoff between performance and complexity. Simulation and experiment results show that the proposed receiver outperforms the conventional RAKE receiver considerably, and most importantly, the proposed PSP receiver with an exact wideband dictionary maintains an excellent performance even for challenging underwater acoustic channels with large Doppler disparities on different paths.
Measurements of the impedance matrix of a thermoacoustic core: Applications to the design of thermoacoustic engines
Authors: Bannwart Flávio C. , Penelet Guillaume , Lotton Pierrick , Dalmont Jean-Pierre
Published: May 2013

The successful design of a thermoacoustic engine depends on the appropriate description of the processes involved inside the thermoacoustic core (TAC). This is a difficult task when considering the complexity of both the heat transfer phenomena and the geometry of the porous material wherein the thermoacoustic amplification process occurs. An attempt to getting round this difficulty consists in measuring the TAC transfer matrix under various heating conditions, the measured transfer matrices being exploited afterward into analytical models describing the complete apparatus. In this paper, a method based on impedance measurements is put forward, which allows the accurate measurement of the TAC transfer matrix, contrarily to the classical two-load method. Four different materials are tested, each one playing as the porous element allotted inside the TAC, which is submitted to different temperature gradients to promote thermoacoustic amplification. The experimental results are applied to the modeling of basic standing-wave and traveling-wave engines, allowing the prediction of the engine operating frequency and thermoacoustic amplification gain, as well as the optimum choice of the components surrounding the TAC.
Observations of shallow water marine ambient sound: The low frequency underwater soundscape of the central Oregon coast
Authors: Haxel Joseph H. , Dziak Robert P. , Matsumoto Haru
Published: May 2013

A year-long experiment (March 2010 to April 2011) measuring ambient sound at a shallow water site (50 m) on the central OR coast near the Port of Newport provides important baseline information for comparisons with future measurements associated with resource development along the inner continental shelf of the Pacific Northwest. Ambient levels in frequencies affected by surf-generated noise (f < 100 Hz) characterize the site as a high-energy end member within the spectrum of shallow water coastal areas influenced by breaking waves. Dominant sound sources include locally generated ship noise (66% of total hours contain local ship noise), breaking surf, wind induced wave breaking and baleen whale vocalizations. Additionally, an increase in spectral levels for frequencies ranging from 35 to 100 Hz is attributed to noise radiated from distant commercial ship commerce. One-second root mean square (rms) sound pressure level (SPLrms) estimates calculated across the 10–840 Hz frequency band for the entire year long deployment show minimum, mean, and maximum values of 84 dB, 101 dB, and 152 dB re 1 μPa.
Nighttime foraging by deep diving echolocating odontocetes off the Hawaiian islands of Kauai and Ni'ihau as determined by passive acoustic monitors
Authors: Au Whitlow W. L. , Giorli Giacomo , Chen Jessica , Copeland Adrienne , Lammers Marc , Richlen Michael , Jarvis Susan , Morrissey Ronald , Moretti David , Klinck Holger
Published: May 2013

Remote autonomous ecological acoustic recorders (EARs) were deployed in deep waters at five locations around the island of Kauai and one in waters off Ni'ihau in the main Hawaiian island chain. The EARs were moored to the bottom at depths between 400 and 800 m. The data acquisition sampling rate was 80 kHz and acoustic signals were recorded for 30 s every 5 min to conserve battery power and disk space. The acoustic data were analyzed with the M3R (Marine Mammal Monitoring on Navy Ranges) software, an energy-ratio-mapping algorithm developed at Oregon State University and custom MATLAB programs. A variety of deep diving odontocetes, including pilot whales, Risso's dolphins, sperm whales, spinner and pan-tropical spotted dolphins, and beaked whales were detected at all sites. Foraging activity typically began to increase after dusk, peaked in the middle of the night and began to decrease toward dawn. Between 70% and 84% of biosonar clicks were detected at night. At present it is not clear why some of the known deep diving species, such as sperm whales and beaked whales, concentrate their foraging efforts at night.
Acoustic properties of low growing plants
Authors: Horoshenkov Kirill V. , Khan Amir , Benkreira Hadj
Published: May 2013

The plane wave normal incidence acoustic absorption coefficient of five types of low growing plants is measured in the presence and absence of soil. These plants are generally used in green living walls and flower beds. Two types of soil are considered in this work: a light-density, man-made soil and a heavy-density natural clay base soil. The absorption coefficient data are obtained in the frequency range of 50–1600 Hz using a standard impedance tube of diameter 100 mm. The equivalent fluid model for sound propagation in rigid frame porous media proposed by Miki [J. Acoust. Soc. Jpn. (E) 11, 25–28 (1990)] is used to predict the experimentally observed behavior of the absorption coefficient spectra of soils, plants, and their combinations. Optimization analysis is employed to deduce the effective flow resistivity and tortuosity of plants which are assumed to behave acoustically as an equivalent fluid in a rigid frame porous medium. It is shown that the leaf area density and dominant angle of leaf orientation are two key morphological characteristics which can be used to predict accurately the effective flow resistivity and tortuosity of plants.
Exploiting randomness in acoustic impulse responses to achieve headphone compensation through deconvolution
Authors: Kelly Ian J. , Boland Francis M.
Published: May 2013

This paper presents a method of headphone/earphone equalization based upon deconvolution of the headphone impulse response from other acoustic filters in the processing chain. The methods presented are thus applicable to areas such as spatial audio, where input signals are processed with binaural impulse responses. The extraction of low order from higher order acoustic impulse responses is justified based upon an application of the theory pertaining to the clustering of the zeros of random coefficient polynomials about the unit circle. An argument is presented supporting the applicability of this theory to acoustic impulse responses. Such an equalization method guarantees a considerable reduction in computational effort over traditional separate compensating filters. A comparison is presented of the implementation of the equalization using the homomorphic method and least squares method with and without regularization to a traditional separate least squares inverse filter. The proposed approach is shown to have a performance comparable to a separate least squares designed compensator, often giving superior performance despite a large reduction in complexity.
Binaural dereverberation based on interaural coherence histograms
Authors: Westermann Adam , Buchholz Jörg M. , Dau Torsten
Published: May 2013

A binaural dereverberation algorithm is presented that utilizes the properties of the interaural coherence (IC) inspired by the concepts introduced in Allen et al. [J. Acoust. Soc. Am. 62, 912–915 (1977)]. The algorithm introduces a non-linear sigmoidal coherence-to-gain mapping that is controlled by an online estimate of the present coherence statistics. The algorithm automatically adapts to a given acoustic environment and provides a stronger dereverberation effect than the original method presented in Allen et al. [J. Acoust. Soc. Am. 62, 912–915 (1977)] in most acoustic conditions. The performance of the proposed algorithm was objectively and subjectively evaluated in terms of its impacts on the amount of reverberation and overall quality. A binaural spectral subtraction method based on Lebart et al. [Acta Acust. Acust. 87, 359–366 (2001)] and a binaural version of the original method of Allen et al. were considered as reference systems. The results revealed that the proposed coherence-based approach is most successful in acoustic scenarios that exhibit a significant spread in the coherence distribution where direct sound and reverberation can be segregated. This dereverberation algorithm is thus particularly useful in large rooms for short source-receiver distances.
Influence of a forest edge on acoustical propagation: Experimental results
Authors: Swearingen Michelle E. , White Michael J. , Guertin Patrick J. , Albert Donald G. , Tunick Arnold
Published: May 2013

Acoustic propagation through a forest edge can produce complicated pressure time histories because of scattering from the trees and changes in the microclimate and ground parameters of the two regions. To better understand these effects, a field experiment was conducted to measure low-frequency acoustic pulses propagating in an open field, a forest, and passing through a forest edge in both directions. Waveforms measured in the open field were simple impulses with very low scattering, whereas waveforms at the edge and within the forest had stronger reverberations after the direct arrival. The direct wave pulse shapes increased in duration in accordance with the path length in the forest, which had an effective flow resistivity 12 to 13 that of the grassy open field. The measurements exhibit different rates of attenuation in the two regions, with relatively lower attenuation in the open field than higher rates in the forest. Decay of SEL transmitted into the forest was 4 dB more per tenfold distance than for outbound transmission. Stronger attenuation in the 1–2 kHz range occurs when propagating into the forest. While the measured meteorological profiles revealed three distinct microclimates, meteorological effects are not sufficient to explain the apparent non-reciprocal propagation.
The depth-dependence of rain noise in the Philippine Sea
Authors: Barclay David R. , Buckingham Michael J.
Published: May 2013

During the Philippine Sea experiment in May 2009, Deep Sound, a free-falling instrument platform, descended to a depth of 5.1 km and then returned to the surface. Two vertically aligned hydrophones monitored the ambient noise continuously throughout the descent and ascent. A heavy rainstorm passed over the area during the deployment, the noise from which was recorded over a frequency band from 5 Hz to 40 kHz. Eight kilometers from the deployment site, a rain gauge on board the R/V Kilo Moana provided estimates of the rainfall rate. The power spectral density of the rain noise shows two peaks around 5 and 30 kHz, elevated by as much as 20 dB above the background level, even at depths as great as 5 km. Periods of high noise intensity in the acoustic data correlate well with the rainfall rates recovered from the rain gauge. The vertical coherence function of the rain noise has well-defined zeros between 1 and 20 kHz, which are characteristic of a localized source on the sea surface. A curve-fitting procedure yields the vertical directional density function of the noise, which is sharply peaked, accurately tracking the storm as it passed over the sensor station.
Effects of hearing loss on the subcortical representation of speech cues
Authors: Anderson Samira , Parbery-Clark Alexandra , White-Schwoch Travis , Drehobl Sarah , Kraus Nina
Published: May 2013

Individuals with sensorineural hearing loss often report frustration with speech being loud but not clear, especially in background noise. Despite advanced digital technology, hearing aid users may resort to removing their hearing aids in noisy environments due to the perception of excessive loudness. In an animal model, sensorineural hearing loss results in greater auditory nerve coding of the stimulus envelope, leading to a relative deficit of stimulus fine structure. Based on the hypothesis that brainstem encoding of the temporal envelope is greater in humans with sensorineural hearing loss, speech-evoked brainstem responses were recorded in normal hearing and hearing impaired age-matched groups of older adults. In the hearing impaired group, there was a disruption in the balance of envelope-to-fine structure representation compared to that of the normal hearing group. This imbalance may underlie the difficulty experienced by individuals with sensorineural hearing loss when trying to understand speech in background noise. This finding advances the understanding of the effects of sensorineural hearing loss on central auditory processing of speech in humans. Moreover, this finding has clinical potential for developing new amplification or implantation technologies, and in developing new training regimens to address this relative deficit of fine structure representation.
A parametric model and estimation techniques for the inharmonicity and tuning of the piano
Authors: Rigaud François , David Bertrand , Daudet Laurent
Published: May 2013

Inharmonicity of piano tones is an essential property of their timbre that strongly influences the tuning, leading to the so-called octave stretching. It is proposed in this paper to jointly model the inharmonicity and tuning of pianos on the whole compass. While using a small number of parameters, these models are able to reflect both the specificities of instrument design and tuner's practice. An estimation algorithm is derived that can run either on a set of isolated note recordings, but also on chord recordings, assuming that the played notes are known. It is applied to extract parameters highlighting some tuner's choices on different piano types and to propose tuning curves for out-of-tune pianos or piano synthesizers.
Effect of spectral change enhancement for the hearing impaired using parameter values selected with a genetic algorithm
Authors: Chen Jing , Baer Thomas , Moore Brian C. J.
Published: May 2013

Chen et al. [J. Acoust. Soc. Am. 131, 2987–2998 (2012)] evaluated the effectiveness of an algorithm for enhancing spectral changes over time in improving the intelligibility of speech in background sounds for hearing-impaired subjects. The processing improved intelligibility for speech in steady speech-spectrum noise (SSN) but tended to impair intelligibility in a background of two-talker speech (TTS). Large individual differences were found. The present study assessed whether the effectiveness of the algorithm was improved when the parameters that controlled the degree and type of enhancement were chosen individually for each subject, using a genetic algorithm based on subjective preferences for speech clarity. The parameter values selected by the genetic algorithm varied markedly across subjects. Speech intelligibility was measured for unprocessed stimuli and stimuli processed using the selected parameters, with SSN and TTS maskers and two signal-to-masker ratios (SMRs) for each subject. The intelligibility of speech in the SSN masker at the lower SMR was improved about 14 percentage points by the processing. The overall improvement produced by the processing was significantly larger than the improvement observed in the previous study when the parameter values were fixed across subjects, indicating that use of the genetic algorithm was beneficial.
The value of a kurtosis metric in estimating the hazard to hearing of complex industrial noise exposures
Authors: Qiu Wei , Hamernik Roger P. , Davis Robert I.
Published: May 2013

A series of Gaussian and non-Gaussian equal energy noise exposures were designed with the objective of establishing the extent to which the kurtosis statistic could be used to grade the severity of noise trauma produced by the exposures. Here, 225 chinchillas distributed in 29 groups, with 6 to 8 animals per group, were exposed at 97 dB SPL. The equal energy exposures were presented either continuously for 5 d or on an interrupted schedule for 19 d. The non-Gaussian noises all differed in the level of the kurtosis statistic or in the temporal structure of the noise, where the latter was defined by different peak, interval, and duration histograms of the impact noise transients embedded in the noise signal. Noise-induced trauma was estimated from auditory evoked potential hearing thresholds and surface preparation histology that quantified sensory cell loss. Results indicated that the equal energy hypothesis is a valid unifying principle for estimating the consequences of an exposure if and only if the equivalent energy exposures had the same kurtosis. Furthermore, for the same level of kurtosis the detailed temporal structure of an exposure does not have a strong effect on trauma.
What is “clarity,” and how it can be measured?
Authors: Griesinger David H.
Published: May 2013

Human hearing did not evolve to detect reflections and reverberation. It is the ability to detect the direct component of a sound field that allows us to separate simultaneous signals, determine their direction, their timbre, their distance, and their importance for our attention. “Clarity” is perceived when we can separately detect direct sound. But ISO3382 measures concentrate on reflections, and are either blind to the direct component of a sound field or misinterpret its significance. They fail to predict sound quality in individual seats. We will demonstrate the vital importance of clarity through demonstrations of “clear” and “muddy” in speech and music. We will then present three physiologically based methods that measure the degree of clarity in a particular acoustic environment. The first, LOC, uses a simple nerve firing model to analyze an impulse response for the build-up of reflected energy at the onsets of sounds. The second method measures the degree of phase randomization above 1000 Hz caused by a particular impulse response. The third measure—based on a computer model of human hearing—measures clarity directly from binaurally recorded speech. All three measures predict perceived clarity with useful accuracy.
On the effects of pre-processing of impulse responses in the evaluation of acoustic parameters on room acoustics
Authors: Venturi Andrea , Farina Angelo , Venturi Andrea
Published: May 2013

The evaluation of room acoustics characteristics in rooms has been thoroughly described in several papers since 1960s. Moreover, the ISO 3382 standard describes several acoustic parameters and their measurements. However, there are only a few information about the methods of pre-processing the impulse responses that are required before calculating those acoustic parameters. In this paper, the main processing methods (based on Luneby, Chu, and Hirata methods) are analyzed. Moreover, they are compared with the Schroeder (background integrated) methods. In a further step, these methods are applied in some acoustic measurements employed in some opera houses in Italy. Finally, after a full discussion about the uncertainties that is beyond these methods, the acoustic parameters are compared with the JND that is actually accepted in the evaluation of the mono-aural, binaural, and spatial acoustic parameters.
A contrast source inversion method for breast cancer detection
Authors: Ozmen-Eryilmaz N. , van Dongen K.
Published: May 2013

Tomographic ultrasound imaging is gaining popularity in breast cancer detection. Reconstructing the acoustic properties of a breast from the ultrasound measurements is stated as a nonlinear inverse problem, which is usually solved by linearized methods because of computational efficiency. However, linearization of the problem reduces the quality of the reconstruction. To improve the accuracy, we developed and tested a three-dimensional nonlinear inversion method that allows for three-dimensional reconstruction of the breast in terms of speed of sound. The method, referred to as contrast source inversion (CSI), uses an integral equation formulation to describe the inverse acoustic scattering problem. The resulting integral equation is solved to reconstruct the unknown contrast (speed-of-sound profile of the breast). The contrast and contrast sources (the product of the contrast with the total field) are iteratively updated by minimizing a cost functional using conjugate gradient directions. In this study, we tested the CSI method on synthetic data retrieved form full-wave simulations for a realistic three-dimensional cancerous breast model. Results show that the CSI method outer performs other conventional methods as it yields speed-of-sound reconstructions that are akin to the model. This shows that the approach offers a contribution to the detection of breast cancer.
Finite element simulation of a two-dimensional standing wave thermoacoustic engine
Authors: de Jong Jan A. , Wijnant Ysbrand H. , de Boer André
Published: May 2013

A finite element analysis has been performed on a theoretical two-dimensional standing wave thermoacoustic engine using the linearized thermoacoustic equations in the frequency domain. This analysis is used to obtain the stability curve of the thermoacoustic engine, which in turn is used to calculate the oscillation onset temperature difference across the stack. The results are compared with existing theory including the long-pore approximation, as originally derived by Rott et al. In addition, the time-averaged effects of the acoustic wave are obtained using weakly nonlinear thermoacoustic theory. This includes the second order time-averaged equations for energy, momentum, and continuity. The saturation amplitude of the acoustic pressure oscillation and the required heat input to sustain the oscillation is obtained. The theory allows for calculation of acoustic streaming patterns. The particle path calculations provide insight to the minor loss mechanism occurring at the interface between the stack and the free tube for low acoustic velocity amplitudes (laminar flow).
Sound transfer path analysis to model the vibroacoustic behavior of a commercial earmuff
Authors: Boyer Sylvain W. , Doutres Olivier , Sgard Franck , Laville Frédéric , Boutin Jérôme
Published: May 2013

Hearing protection devices (HPD), such as earmuffs, are widely used to protect workers from noisy environments. Numerical predictive tools can be used to simulate the vibroacoustic behavior of earmuffs and thus assess their sound attenuation and improve their acoustical design. The present work describes the implementation of a vibroacoustic finite element numerical model of an earmuff coupled to a rigid baffle in the frequency range from 20 to 5000 Hz. An experimental assessment of the sound transfer paths through each element of the earmuff (cup, cushion, and foam lining) using a specific acoustical test bench is first proposed. This analysis is then used to target the right level of model complexity for each component. An experimental validation of the FEM model is then carried out.
Audio quality evaluation by experienced and inexperienced listeners
Authors: Schinkel-Bielefeld Nadja , Lotze Netaya , Nagel Frederik
Published: May 2013

Basic audio quality of coded audio material is commonly evaluated using ITU-R BS-1534 Multi Stimulus with Hidden Reference and Anchors (MUSHRA) listening test. MUSHRA guidelines call for experienced listeners. However, the majority of consumers using the final product are no expert-listeners. Also the degree of expertise in a listening test may vary among listeners in the same laboratory. It would be useful to know how the audio quality evaluation differs between trained and untrained listeners and how training and actual tests should be designed in order to be as reliable as possible. To investigate the rating differences between experts and non-experts, we performed MUSHRA listening tests with 13 experienced and 11 inexperienced listeners using 5 speech and audio codecs delivering a wide range of basic audio quality. Except for the hidden reference, absolute ratings of non-experts were consistently at least 10% higher than those of experts. However, they could be mapped to each other by a z-transform. For lower quality values, confidence intervals were significantly larger for non-experts than for experts. Experienced listeners set more than twice as many loops as non-experts, compared more often between codecs and listened to high quality codecs for a longer duration than non-experts.
Advanced hearing protection and auditory awareness in individuals with hearing loss
Authors: Giguere Christian , Laroche Chantal , Vaillancourt Véronique
Published: May 2013

In-ear and earmuff-type electronic protection devices are rapidly being introduced into the marketplace and deployed in noisy industrial workplaces and military settings. In these environments, workers must be sufficiently protected from noise while being able to maintain good communication abilities and situational awareness. Features such as level-dependent attenuation or amplification, user-adjustable talk-through circuitry, noise reduction, and remote communication capabilities are commonly found in advanced devices. The benefits of these features depend on their complex interaction with the signal and noise characteristics, the hearing status and language proficiency of the workers, and the nature of the auditory task. Yet, detailed electro-acoustical specifications are rarely reported by manufacturers. Measurement standards are also lacking, though the advent of ANSI/ASA S12.42 should in part address this situation. In this paper, the characteristics of two advanced devices are reported over a test battery including measurements of the passive sound attenuation, level-dependent talk-through sound transmission, and speech recognition in noise for listeners with a wide range of hearing profiles. Electronic level-dependent attenuation provided superior speech recognition performance than passive attenuation for all groups of listeners, and often exceeded unprotected speech recognition performance.
Supplemental text messaging for the resolution of auditory overload
Authors: Abel Sharon M. , Ho Geoffrey , Nakashima Ann , Smith Ingrid
Published: May 2013

Military signal operators listen, transcribe, and respond to audio traffic over multiple audio channels, in high-level noise from vehicles and weapons. The messages typically overlap in time and may be difficult to disentangle. Two studies were carried out to determine the benefit of supplemental texting. Normal-hearing participants were tested in a mock up of a military command post. Brief messages were played simultaneously over a communications headset (dichotic) and a loudspeaker array, either in quiet or in a background of vehicle noise. The at-ear speech-to-noise ratio was 5 dB. Only those messages beginning with a pre-assigned call sign were encoded. Mean scores of 84% or better were observed for messages presented over the headset, although there was a clear right ear advantage in noise. Messages coming over the loudspeakers were more difficult to understand but a visual cue directing attention to the source of an incoming targeted message resulted in a significant improvement of 7%. Replacing audio messages over the loudspeakers in noise with visual or audiovisual presentations resulted in an improvement from 71% to 96% that did not negatively affect headset performance. The data suggest that texting is a viable option for communication in cases of degraded audio.
Integration of a distance sensitive wireless communication protocol to hearing protectors equipped with in-ear microphones
Authors: Bou Serhal Rachel E. , Falk Tiago , Voix Jérémie
Published: May 2013

Using radio communication in noisy environments is a practical and affordable solution allowing communication between workers wearing hearing protection devices (HPD). However, typical radio communication systems have two main limitations when used in noisy environments: first, the background noise is disturbing the voice signal picked-up and transmitted, and second, that voice signal goes to all listeners on the same radio channel regardless of their physical proximity. A new concept of a so-called “Radio-Acoustical Virtual Environment” (RAVE) addressing these two issues is presented. Using an intra-aural instantly custom molded HPD equipped with both an in-ear microphone and miniature loudspeaker, undisturbed speech is captured from inside the ear canal and transmitted over the wireless radio to the remote listener. The transmitted signal will only be received by listeners within a given spatial range, such range depending on the user’s vocal effort and background noise level. This paper demonstrates the technological challenges to overcome and the methodology involved in the implementation of RAVE.
Acoustical indicator of noise annoyance due to tramway in in-curve operating configurations
Authors: Trollé Arnaud , Marquis-Favre Catherine , Klein Achim
Published: May 2013

Tramway gives rise to annoyance. Particularly, tramway in an in-curve operating configuration often emits squeal noises leading to inhabitants’ complaints. Noise exposure levels were not sufficient to account for annoyance. Other acoustical factors could explain noise annoyance. A laboratory experiment is carried out in order to identify and characterize the influential acoustical factors of in-curve tramway noises. Subjects are asked to rate the short-term annoyance caused by 14 tramway pass-by noises, recorded in situ for various in-curve operating configurations. A psychoacoustical analysis shows that the overall perceived noise level, the irregular character and the treble character of tramway noises influence noise annoyance. These acoustical features are taken into account through the following indices: the mean loudness, the variance of time-varying A-weighted pressure normalized by RMS A-weighted pressure, and a psychoacoustical index, constructed to account for squeal noise, expressed by the total energy of the tonal components within critical bands from 12 to 24 Barks. A multilevel regression analysis reveals that a combination of these indices proves to be satisfactory for predicting short-term annoyance due to in-curve tramway noises. These results are consistent with those from a previous experiment that implied 61 tramway pass-by noises corresponding to different operating situations.