bluuebunny/crossref_metadata_2025 huggingface dataset:
Drill rod Coulomb friction damper.
Authors: Guthrie Anne , Scarton Henry
Published: March 2010

The acoustical performance of a case-hardened Coulomb friction damper consisting of a case-hardened roll-threaded collar resting against a reverse taper segment of drill rod is discussed. Because of the axial impact, many transverse bending modes of vibration are excited in long prismatic drill rod, along with longitudinal and torsional resonances. The self-tightening nature of the collar that is caused to simultaneously move axially due to its inertia and rotate on the rolled thread and consequently press on the case-hardened tapered surface of the drill rod induces interfacial frictional rubbing which is conclusively shown to be present resulting in 30 dB of attenuation of the modes of vibration. These observations are experimentally shown and theoretically verified.
Evaluation of noise exposures of miners operating highwall mining equipment.
Authors: Bowers Link
Published: March 2010

Modern highwall mining systems are starting to replace surface coal augers in some highwall mining operations because of their ability to increase coal production and recovery rates. Another benefit of using highwall mining systems instead of surface coal augers is the reduction in noise exposures to the affected miners extracting the coal from the highwall. Several surface coal augers and highwall mining systems were evaluated for full shift noise exposures of the machine operator and helpers during this investigation. Engineering noise controls were also evaluated for each piece of highwall mining equipment. The operator and helper working on a modern highwall mining system were exposed to average sound pressure levels of 61.5 and 89.0 dBA, respectively, while the operator and helper working on a surface coal auger were exposed to higher average sound pressure levels of 95.4 and 94.0 dBA, respectively.
Wave propagation characteristics in mud-filled drilling pipe.
Authors: Patil Abhay , Kim Yong-Joe
Published: March 2010

The objective of this study is to analytically and experimentally analyze the wave propagation characteristics of a mud-filled drilling pipe in terms of wave speed and spatial decay rate. Here, the pipe is modeled as an elastic hollow pipe and the inside mud as a fluid. A wave equation of the mud is then derived based on the assumption of one-dimensional plane wave propagation that is valid in low frequencies. This wave equation is coupled with the equation of motion of the elastic pipe. For the purpose of validating the analytical wave solutions of the wave equation, an experiment is performed with a mud-filled pipe. The pipe is driven by a piston at one end and the resulting dynamic responses are then measured with an array of strain gauges installed on the external surface of the pipe along the axial direction at the other end. A wave decomposition procedure is applied to the measured data to separate direct and reflective waves. The direct waves are then used to calculate their phase speeds and spatial decay rates. It is shown that the experimentally measured wave propagation characteristics are successfully used to validate and improve the analytical model.
Weapon noise exposure of the soldier and its measurement.
Authors: Buck Karl , Hamery Pascal
Published: March 2010

On the battlefield a soldier is continuously exposed to various types of noise. Much of this exposure is noise generated by his own weapon or by weapons of close by troops. The exposure levels are between 160-dB peak for small arms and 190-dB peak at the soldier’s ear for some antitank weapons, with A-durations from 0.3 ms (small caliber) to 4 ms for large caliber weapons (e.g., Howitzers). As these parameters feed into the damage risk criteria which are in use by the armed forces of different countries, it is important that the recorded pressure time histories are as precise as possible. The paper will present the acoustic levels to which a soldier may be exposed by different types of weapon and under different circumstances. It also will present measurement techniques to use for reliable results.
Measurement and characterization of army impulsive noise sources.
Authors: Kalb Joel T.
Published: March 2010

Peak pressure levels in army noise environments range from 140- to 195-dB near soldiers firing energetic weapons and are all dangerous to unprotected ears. Blast reverberation in confined spaces and steady noise in armored vehicles is also hazardous, so complete assessment requires the widest possible measurement range. To accurately measure pressures in the free-field or under hearing protectors, microphone considerations include type, location, orientation, mounting, shape, and shielding from flash or mechanical shock. Blast-waves rise instantaneously and return to free-field ambient within 0.3–15 ms, while in enclosures this can increase to 100 ms, requiring wide bandwidth signal processing. In addition to hazard, acoustic detection and annoyance at greater distances from weapons involve propagation effects in the atmosphere and at the ground which alter the wave-shape.
Application of near-field acoustical holography to high-performance jet aircraft noise.
Authors: Wall Alan T. , Gee Kent L. , James Michael M. , Gardner Michael D.
Published: March 2010

Near-field acoustical holography (NAH) measurements were made to visualize the sound field in the jet exhaust region of an F-22 Raptor. This is one of the largest-scale applications of NAH since its development in the 1980s. A scan-based holographic measurement was made using a 90-microphone array with 15-cm regular grid spacing for four engine power settings. The array was scanned through 93 measurement positions along three different measurement planes in a region near 7 m from the jet centerline and 23 m downstream. In addition, 50 fixed reference microphones were placed along the ground 11.6 m from the jet centerline, spanning 30.8 m. The reference microphones have been used to perform virtual coherence on the measurement planes. Statistically optimized NAH has been used to backpropagate the sound field to the source region for low frequencies and to identify jet noise characteristics. Ground reflection interference and other non-ideal measurement conditions must be dealt with. Details relating to jet coherence-lengths and their relation to reference microphone requirements will be discussed. Preliminary results of this ongoing work will be presented. [Work supported by Air Force SBIR.]
A hearing protector model for predicting impulsive noise hazard.
Authors: Kalb Joel
Published: March 2010

Reduction in impulsive noise hearing hazard by earplugs and earmuffs is calculated with an electroacoustic lumped-parameter model of HPD attenuation using real ear attenuation at threshold (REAT) data. Energy flows into the occluded volume along three paths, each considered as a piston: (1) the rigid protector mass moving against the skin, (2) leakage at the support, and (3) transmission through the protector material (a second piston within the rigid piston). Circuit elements are adjusted so loss matches REAT data assuming path 1 is important at low, 2 at middle, and 3 at high REAT frequencies. Applying the model to 384 REAT data sets for ANSI S12.6 method B naive users gives statistical frequency distributions of occluded volume and leakage elements. For a given free-field impulsive noise, the model pressure predictions under the protector are compared to measurements on human and acoustical manikin ears to check validity of assumptions. The hearing hazards of the measured waveforms and the predicted waveforms are calculated with our previously developed auditory hazard analysis algorithm for humans ear model. The result is a cumulative frequency distribution of hazard based on user fit data useful in finding the best protector for a given impulsive noise.
Comparative study of a proposed time varying loudness standard for common sounds.
Authors: Novak Colin , Ule Helen , Letowski Tomasz
Published: March 2010

Several calculation procedures exist and are standardized for the determination of loudness of steady sounds. While loudness models for unsteady sounds do presently exist, they differ in their outcomes and have not been yet sufficiently validated using round robin or other appropriate evaluation methodology. Recently, the Deutsches Institut fur Normung (DIN) announced that it will soon issue a new standard describing a method for calculation of loudness of time-varying sounds. However, the DIN 45631-A1 takes a less common approach in that it does not fully describe a methodology to calculate the unsteady loudness. It instead offers a more general procedure along with open-ended checks and balances for verifying the progress through the various calculation steps. The caveat of this is that while conditions specified by this standard may be satisfied, varying results may be achieved due to the procedures’ open architecture. Conversely, the checks and balances may be enough such that identical results are achieved for the same sounds. This study investigates several commercial applications using this standard and compares their results for several common inputs. The results of the study will be discussed in terms of the extent to which compliance with DIN 45631-A1 results in identical loudness scores.
New options in microphones and instrumentation for making field infrasonic measurements.
Authors: Veggeberg Kurt
Published: March 2010

There are many interesting man-made, animal, and other naturally occurring infrasonic signals. Typical measurement microphones and instrumentation systems are usually ac coupled and roll-off at various frequencies below 20 Hz since they were primarily designed for audible sound. Making infrasonic measurements has often used a variety of sensors or microphones that are not uniform or compliant with international standard IEC 1094 for dimensions of measurement microphones but offer capabilities for measuring to frequency ranges below 1 Hz. In addition, they typically are not compliant with ANSI or IEC standards for sound level meters. This is an overview of new IEPE/ICP condenser type measurement microphones and instrumentation capable of making measurements below 0.5 Hz and how they can be deployed in making precision acoustic field measurements compliant with acoustic standards at very low-frequency ranges.
Experience of the measurement and assessment of residential low-frequency noise complaints.
Authors: Waddington David C. , Moorhouse Andrew T. , Adams Mags D.
Published: March 2010

The practical application of a procedure for the assessment of low-frequency noise (LFN) complaints is described. The development of the assessment method was published recently [J. Acoust. Soc. Am. 126, 1131–1141 (2009)]. The procedure includes guidance notes and a pro-forma report with step-by-step instructions for field measurements, complemented with an interview-based questionnaire together with an event log completed by the complainant. It does not provide a prescriptive indicator of nuisance but rather gives a systematic procedure to help environmental health practitioners to form their own opinion. Examples of field measurements and application of the procedure are presented. The procedure and examples are likely to be of interest to environmental health practitioners involved in the assessment of LFN complaints. [Work funded by the Department for Environment, Food and Rural Affairs (Defra), UK.]
Ultrasonic noise from manmade electical devices.
Authors: Jenny Trevor , Anderson Brian E. , TenCate James A.
Published: March 2010

Measurements of ultrasonic noise emitted from manmade electrical devices have been made in an ultrasonic anechoic chamber. Until now, little has been published about the levels and frequency content of ultrasonic noise emitted from electronic devices such as laptops, cell phones, and other electronic devices. The most common source of ultrasonic noise in these devices is dc to dc power supplies. Measurements are made over the range of 20–200 kHz emitted by electronic devices (e.g., laptops). The results of these measurements and the challenges associated with making the measurements will be discussed (including anechoic chamber qualification in the ultrasonic frequency range). [This work has been funded by the Los Alamos National Laboratory.]
Random focusing of nonlinear N-waves in fully developed turbulence: Laboratory scale experiment and theoretical analysis.
Authors: Blanc-Benon Philippe , Averiyanov Mikhail V. , Ollivier S. , Khokhlova Vera A.
Published: March 2010

The high-amplitude shock wave generated by a supersonic aircraft propagates through the atmosphere toward the ground and generates an acoustic field with non-uniform pressure distributions strongly influenced by atmospheric turbulence. Recent numerical simulations based on generalized KZK-type equation including the effects of moving inhomogeneous media will be discussed. Formation of multiple focusing and defocusing zones is predicted. Nonlinear effects are significant not only in the random focusing zones but also in shadow zones of lower-pressure levels due to scattering of high frequencies from the areas of focusing. A statistical analysis is performed, and the results are compared to experimental data obtained in the controlled laboratory scale experiments conducted in the ECL anechoic wind tunnel. A high-power spark source is used to generate N-waves. Correlation length scales and spectra of the turbulent velocity field are measured. Statistical distributions and mean values for peak positive pressure and shock arrival time are obtained and found to be in a good agreement with modeling. In focusing areas, waveforms with amplitudes more than four times higher than those measured without turbulence are observed. Pressure amplitude probability density distributions are shown to possess autosimilarity properties when changing the intensity of turbulence. [Work supported by RFBR, French Government.]
Investigation into and modelling of head movement for objective evaluation of the spatial impression of audio.
Authors: Kim Chungeun , Mason Russell , Brookes Tim
Published: March 2010

Research was undertaken to determine the nature of head movements made when judging spatial impression and to incorporate these into a system for measuring, in a perceptually relevant manner, the acoustic parameters which contribute to spatial impression: interaural time and level differences and interaural cross-correlation coefficient. First, a subjective test was conducted that showed that (i) the amount of head movement was larger when evaluating source width and envelopment than when judging localization and timbre and (ii) the pattern of head movement resulted in ear positions that formed a sloped area. These findings led to the design of a binaural signal capture technique using a sphere with multiple microphones, mounted on a simulated torso. Evaluation of this technique revealed that it would be appropriate for the prediction of perceived spatial attributes including both source direction and aspects of spatial impression. Reliable derivation of these attributes across the range of ear positions determined from the earlier subjective test was shown to be possible with a limited number of microphones through an appropriate interpolation and calculation technique. A prototype capture system was suggested as a result, using a sphere with torso, with 21 omnidirectional microphones on each side. [Work supported by the Engineering and Physical Sciences Research Council (EPSRC), UK, Grant No. EP/D049253.]
Radiation reduction using layers of three fluids.
Authors: Nagy Adam J. , Norris Andrew N.
Published: March 2010

Significant reduction in target strength and radiation signature can be achieved by surrounding an object with multiple concentric layers comprised of three acoustic fluids. The idea is to make a finely layered shell with the thickness of each layer defined by a unique transformation rule. The shell has the effect of steering incident acoustic energy around the structure and, conversely, reducing the radiation strength. The overall effectiveness and the precise form of the layering depend upon the densities and compressibilities of the three fluids. The best results are obtained if one fluid has density equal to the background fluid, while the other two densities are much greater and much less than the background values. Optimal choices for the compressibilities are also found. Simulations in two dimensions and three dimensions illustrate the effectiveness of the three-fluid shell.
Perceptual expectations, attention, and speech recognition.
Authors: Nusbaum Howard C.
Published: March 2010

Research has demonstrated substantial plasticity in the adult speech perceiver. When listeners receive feedback about the classification of a speech signal, this feedback can shape attention affecting phoneme perception. This demonstrates that it is possible to shape perceptual attention prospectively changing subsequent speech perception. These changes can also reduce the cognitive load of speech perception. The effect of expectations on speech perception has been reported for a wide range of studies from sinewave speech perception to phonetic categorization and effects of talker variability. Neural changes occurring during learning and the neural effects of expectations both appear to involve regions of motor cortex implicated in speech production. These neural changes suggest a model of speech perception similar to analysis-by-synthesis in which sensory processes are tuned by activity within the speech motor system. Although such sensory-motor interactions have been implicated in speech perception due to coarticulation and the encoding of speech into sound, the role of expectations in speech perception may extend beyond segmental perception. We consider evidence that the interpretation of prosodic signals also depends on perceptual expectations, suggesting that the role of expectations may be to constrain recognition given the many-to-many relationship that holds broadly in speech.
Hot topics in musical acoustics.
Authors: Rossing Thomas D. , Cottingham James P.
Published: March 2010

Musical acoustics deals with the production, transmission, and perception of musical sound, as well as the scientific study of musical performance. It interfaces with physics, music, psychology, engineering, architecture, audio engineering, and neurology, and it is often at these interfaces that some of the hottest topics occur. For example, functional magnetic resonance imaging (fMRI) and electro- and magneto-encephalography (MEG and EEG) have made it possible to study music and the brain and to localize neural processing of musical activity. Digital computers have made it possible to synthesize musical sound with every increasing refinement using such methods as physical modeling, waveguide models, and commuted synthesis. Systems for real-time, high-quality, and low-latency audio over the internet have made it possible for performers at distant locations to play in concert. New acoustical musical instruments, as well as modifications of existing instruments, enrich musical performance, while new performing groups such as laptop and cellphone orchestras appear at many universities.
Glass breakage by blasts: A prediction model and real-world validation.
Authors: Sutherland Louis C.
Published: March 2010

The structural elements most sensitive to blast damage are usually windows. A classic paper by Hershey et al. [J. Acoust. Soc. Am. 55, 1009–1017 (1974)] developed a powerful statistical model for damage to windows from impulsive (sonic boom) pressure loads. The key part of the model depended on both the pressure load and failure stress having a log normal distribution; that is, the log of these variables was normally distributed. This basic concept, applied by the author in several studies on blast and sonic boom damage, is briefly reviewed here for application to blast damage to windows. Validation of the model is provided by data from an accidental explosion of an equivalent 20 lbs of TNT near a nearby nine-building apartment complex. 58 windows were broken, fortunately without any injuries. The predicted damage was augmented by results of a model study of diffraction around a cubical obstacle to approximate the changes in the net pressure loading on the apartment building windows located at various orientations to the blast wave front. The predicted window breakage rate, varying from 0.5% to 61% compared well with the observed values in the range of 0–64%. [Work supported by Wyle Labs.]
A perceptive categorization of sounds produced the interaction of solid objects.
Authors: Houix Olivier , Lemaitre Guillaume , Misdariis Nicolas , Susini Patrick , Urdapilleta Isabel
Published: March 2010

The literature on the perception of environmental sounds often postulates that these sounds are perceptually organized according to their cause. In a previous study, we found experimental results consistent with this assumption by showing that, in the case of identifiable sounds and non-expert listeners, main categories of liquids, gases, electrical devices, and solids appear. We report here a study specifically exploring this latter category. Participants were required to categorize a set of sounds according to the actions causing the sound and to describe the resulting categories. We analyze the classifications with a specific hierarchal cluster analysis producing two dendrograms. The second dendrogram is used to highlight a possible secondary categorization that may add to the primary categorization. Therefore, this technique allows taking into account the multiple types of similarity that might occur in a categorization task. This statistical analysis of the classifications was complemented by a linguistic analysis of the descriptions of the categories (ALCESTE and LEXICO). This analysis shows two main categories of descriptions: those describing several objects in interaction and those describing modifications of an object. Eventually, we discuss how hierarchical cluster and linguistic analyses complement to provide a portrait of the perceptive categorization of sounds of solids.
How do listeners react to different urban soundscapes? A functional magnetic resonance imaging study of perception and emotion.
Authors: Hall Deborah , Irwin Amy , Plack Christopher
Published: March 2010

This research formed one part of a multi-disciplinary positive soundscapes project investigating the perception of urban sound environments. To determine the neural correlates associated with perceptual and affective responses to such sounds, we have measured ongoing brain activity using functional magnetic resonance imaging. Sixteen participants were scanned while passively listening to a set of recordings made in urban spaces. In total, there were 150 recordings, each containing multiple sound sources. Soundscapes were matched in overall sound level [71 dB(A)] but differed in their ratings of pleasantness along a five-point scale. As expected listening to urban soundscapes evoked a significant response in a number of auditory brain regions (inferior colliculus, medial geniculate body, and auditory cortex). Crucially, those soundscapes evoking a strong emotional response (either pleasant or unpleasant) activated one of the main emotional centres in the brain—the amygdala. The perceived pleasantness of the soundscape also modulated the auditory response to the sounds. Our results confirm that that loudness is not the only factor that determines how people react to urban soundscapes.
Approaches for ultrasonic damage detection in aircraft components for structural health monitoring.
Authors: Tittmann Bernhard R.
Published: March 2010

Characterization of flaws is an important goal of ultrasonic NDE in aircraft components, especially to meet the new demands for structural health monitoring to achieve retirement for cause. This presentation describes approaches and results for two classes of damage: (1) impact damage in fiber-reinforced composites and (2) cracks in jet engine components. In the application of impact damage on composites the use of non-contact laser based ultrasound with a NdYAG laser as transmitter and Mach–Zehnder interferometer as receiver was complemented by acoustic microscopy. Results are described for both hard and soft impacts on a variety of composites. In the application of crack detection of jet engine components the main emphasis was on the development for in-situ high-temperature piezoelectric sensors. In particular, high temperature operation in excess of 1000 °C is described with sol-gel spray-on coatings, thin AlN films and single crystals of aluminum nitride. Some of the sensors are geared toward wireless retrieval of crack detection in turbine disks and blades. Whereas these approaches in ultrasonic NDE are not routine they hold high promise for near-future applications in the aerospace.
Intelligibility of accented American English isolated vowel: Effects of fundamental frequency (F0) contour and formant structures.
Authors: Kamdar Sangeeta , Liu Chang , Jin Su-Hyun , Gonzales Dasia
Published: March 2010

Our previous studies have shown that Chinese and Korean accented English vowels deviated in fundamental and formant frequency values and gross spectral shape properties when compared to English-native productions. The present study proposed to examine the intelligibility of accented English vowel by manipulating the fundamental frequency, formant frequencies, and/or entire spectrum shape in an effort to measure the specific contribution of each of these discrete acoustical parameters on accented vowel perception. There were six sets of vowel stimuli: original vowels produced by native and non-native speakers, flat F0 contour with original spectrogram of native and non-native speakers, hybrid vowels mixing non-native F0 contour and native spectrogram, and hybrid vowels mixing native F0 contour and non-native spectrogram. Preliminary results showed that intelligibility was significantly improved for foreign-accented vowels when the non-native spectrogram was replaced with native spectrogram. On the other hand, effects of F0 contour were dependent on talker intelligibility. For non-native speakers with low vowel intelligibility, replacement of F0 contour with native F0 contour slightly increased vowel intelligibility while for non-native speakers with high vowel intelligibility, replacement of F0 contour degraded rather than improved vowel intelligibility.
Suprathreshold auditory processing and speech recognition in noise for hearing-impaired listeners.
Authors: Summers Van , Bernstein Joshua G. W. , Makashay Matthew J. , Mehraei Golbarg , Melamed Sarah , Leek Marjorie R. , Gallun Frederick J. , Molis Michelle
Published: March 2010

Suprathreshold distortions in auditory processing contribute to speech recognition deficits for hearing-impaired (HI) listeners in noise. Outer hair cell damage and attendant reductions in frequency selectivity and peripheral compression may contribute to these deficits. Reduced sensitivity to spectral or temporal modulations or temporal fine structure (TFS) information may also play a role. Eight normal-hearing and 18 HI listeners were tested in psychoacoustic tasks to assess frequency selectivity (notched-noise), peripheral compression (temporal masking curves), TFS sensitivity [frequency modulation (FM) detection in the presence of random amplitude modulation], and spectrotemporal modulation (STM) sensitivity (spectral-temporal “ripple” detection). Performance was examined at 500, 1000, 2000, and 4000 Hz at several presentation levels. Listeners were also tested on sentence recognition in stationary and modulated noise (92-dB sound pressure level signal level; −6-, −3-, 0-, and +3-dB SNRs). HI listeners with similar audiometric thresholds showed a wide range of speech scores. Estimates of FM and STM sensitivity at 500 and 1000 Hz were significantly correlated with speech scores and with each other. Frequency selectivity and compression measures were not clearly associated with speech performance. Implications for models of HI speech intelligibility are discussed. [Work supported by the Oticon Foundation.]
Phoneme perception in temporally and spectrally modulated maskers: Effect of suprathreshold hearing impairment.
Authors: Phatak Sandeep A. , Grant Ken W.
Published: March 2010

Normal-hearing (NH) listeners show better speech recognition in fluctuating maskers than in steady-state (SS) maskers. Hearing-impaired (HI) listeners do not show such benefit due to elevated thresholds. With amplification, HI listeners show some benefit, but significantly less than that for NH listeners. To investigate the reduced benefit in HI listeners at suprathreshold levels, we measured consonant and vowel recognition by NH and aided HI listeners in the presence of SS and modulated maskers. The modulated noises were generated by modulating the SS noise, in either one or six channels, by either one talker speech or four talker babble, resulting in four different modulated masker conditions. HI listeners were provided individualized gain according to the Cambridge formula. Both NH and aided HI listeners showed reduced intelligibility for consonants and vowels due to increase in the number of talkers. Increase in the number of channels provided more benefit to NH listeners than to HI listeners, and this benefit was greater for vowels than for consonants. This benefit due to spectral modulations for aided HI listeners was not correlated with audibility, but seems to be correlated with their ERBs. [Work supported by the Oticon Foundation, Denmark.]
When noise vocoding can improve the intelligibility of sub-critical band speech.
Authors: Bashford James A. , Warren Richard M. , Lenz Peter W.
Published: March 2010

This study examined the redundancy of spectral and temporal information in everyday sentences, which were reduced to 16 rectangular spectral bands having center frequencies ranging from 250 to 8000 Hz, spaced at 1/3-octave intervals. High-order filtering eliminated contributions from transition bands, and the widths of the resulting effectively rectangular speech bands were varied from 4% down to 0.5% (Exp. 1) and from 40 Hz down to 5 Hz (Exp. 2). Intelligibility of these sub-critical bandwidth stimuli ranged from nearly perfect in the 4%- and 40-Hz bandwidth conditions, down to nearly zero in the 0.5%- and 5-Hz bandwidth conditions. However, a large recovery of intelligibility was obtained under adverse filtering conditions when the speech bands were used to vocode broader noise bands that approximated critical bandwidths (ERBn) at the 16 center frequencies. For example, the 0.5%- and 1%-bandwidth speech stimuli were only about 1% and 20% intelligible, respectively, whereas scores of about 26% and 60%, respectively, were obtained for the ERBn-wide modulated noise stimuli derived from the speech bands. These large intelligibility increases occurred despite elimination of spectral fine structure and the addition of stochastic fluctuations to the speech-envelope cues. Additional findings and their implications will be discussed. [Work supported by NIH.]
Linguistic processing of vocoded signals.
Authors: Nittrouer Susan , Lowenstein Joanna H.
Published: March 2010

Tests of word discrimination show that listeners can accurately recognize speech with cochlear implants, but there is more to linguistic processing than these measures evaluate. We examined the possibility that other aspects of processing are hindered. Adults and 8-year-olds participated in two experiments. (1) Serial recall for words presented in each of three ways: natural, vocoded, and embedded in noise. Environmental sounds were control stimuli. (2) Judgments of whether words share the same final consonant using natural words, and those same words vocoded or embedded in noise. Serial recall was less accurate and responding was slower for vocoded than for natural speech, but not as poor as for environmental sounds. For final-consonant judgments, accuracy was not as greatly affected by use of vocoded signals, but response times were slowed. That was true even when only correct responses were considered. In both experiments, adults performed better with speech-in-noise than with vocoded speech, but children performed similarly with the two kinds of signals. Conclusions were: as follows (1) linguistic processing of signals heard through implants can be hindered in ways not typically evaluated (2) that hindrance arises from impoverishment of signal properties required for recovering phonetic structure, rather than from general signal degradation. [Work supported by NIDCD Grant No. DC-00633.]
A preliminary comparison of sound quality of maternal speech recordings in varied neonatal intensive care unit settings.
Authors: Petito Andi C. , Jancek Jessica , Krueger Charlene
Published: March 2010

Since the 1980s, research investigating the beneficial effects of exposure to maternal voice has been steadily increasing. This has been accomplished by playing back recordings of maternal voice to the preterm infants. It is not known, however, how variations in the typical NICU setting alter the sound quality of the original recordings. This is a sub-study to a larger study in which 58 preterm infants will hear a recording of their mother reciting a rhyme twice a day from 28–34 weeks post-menstrual. A pair of microphones will be placed at ear level of the preterm subjects while the original recordings of maternal speech are played. The sound recorded within the incubator will then be run through a sound analyzer (PRAAT) and compared to the same sound qualities of the original recordings. The purpose of this study is to compare the original sound spectrum of a maternal speech recording to spectra obtained while the recording is played within typical NICU settings (open vs closed crib, pillows vs no pillows, etc.) If it is observed that the sound quality is altered due to varied NICU settings, this information will be important in determining NICU sound regulations for future studies employing voice recordings.
Discrimination of voicing on the basis of temporal envelope cues in 6-month old infants.
Authors: Bertoncini Josiane , Cabrera Laurianne , Lorenzi Christian
Published: March 2010

Several studies indicate that profoundly deaf children receiving a cochlear implant (CI) under the age of 2 years are able to develop linguistic skills at a rate equal to similarly aged children with normal hearing. CI devices deliver temporal-envelope (E) cues in speech over a small number of frequency channels. This suggests that infants are able to use efficiently E speech cues at an early age. However, little work has been done to investigate the developmental time course of the ability to use E speech cues. A recent study suggests that normal-hearing children are able to use such cues at adult levels by the age of 5 years, but information is lacking for younger children. The present study assessed the ability of 6-month old infants with normal hearing to discriminate between voiced and unvoiced stop consonants (/aba/ versus /apa/) on the basis of E cues, using a head-turn preference procedure and speech tokens processed via a tone or a noise E vocoder. The spectral and temporal resolutions of vocoders were varied to determine whether or not the ability to use E speech cues is similarly constrained in infants and adults. Preliminary results indicate that this method is applicable to young infants.
Infants’ ability to recognize speech in the presence of amplitude-modulated background noise.
Authors: Newman Rochelle S. , Morini Giovanna
Published: March 2010

Adults experience a release of masking when the amplitude level of a masker varies [Festen and Plomp (1990) and Wilson and Carhart (1969)], especially when the variation occurs in a slow, predictable manner [Gustafsson and Arlinger (1994)]. This pattern of performance has been described as “listening in the dips” of the signal and is a form of selective attention: focusing one’s attention on those time periods of the signal that are likely to be most beneficial. Infants have poor selective attention abilities for different frequency regions [Bargones and Werner (1994)]; if they similarly are less able to attend to particular points in time, they should show no advantage when the amplitude level of a masker varies. We presented infants with either their own name or a foil name in the presence of white noise; the noise was either constant in amplitude or varied at a 10-Hz modulation at a depth of 12 dB. Infants showed a disadvantage when faced with amplitude-modulated background noise (that is, they showed stronger recognition of their name when the noise had a constant amplitude than a varying amplitude), suggesting that the modulation itself may have attracted attention away from the target speech. [Work supported by NSF BCS0642294.]
Acoustic correlates of clear speech vowel intelligibility for elderly hearing-impaired listeners.
Authors: Ferguson Sarah Hargus
Published: March 2010

Earlier work on vowels in clear and conversational speech produced by a single talker suggested that the acoustic cues that underlie the superior intelligibility of clear speech for older adults with hearing loss may differ from the cues that young normal-hearing listeners find beneficial. In the present study, clear and conversational vowel stimuli produced by all 41 talkers from the Ferguson Clear Speech Database were presented in a background of 12-talker babble to 40 older adults with mild-to-moderately severe sloping sensorineural hearing loss. Acoustic analyses (vowel duration, steady-state formant frequencies, and measures of dynamic formant movement) were also performed for all stimuli. Vowel intelligibility scores for each talker in each speaking style as well as the magnitude of the clear speech vowel intelligibility effect for each talker will be compared to those obtained from young listeners with normal hearing in a previous study. Regression and other statistical analyses of intelligibility and acoustic data will also be performed to determine the acoustic correlates associated with improved clear speech vowel intelligibility for each listener group. [Work supported by NIHDCD-008886.]
Efficient and adaptive sparse time-frequency representations through superposition frames.
Authors: Rudoy Daniel , Basu Prabahan , Wolfe Patrick J.
Published: March 2010

Sparsity in signal representation requires two aspects: a large dictionary of potential basis functions that can be adapted to a variety of waveforms and an efficient means of selecting these functions and reconstructing the corresponding signal representation. This talk introduces a family of time-frequency systems termed superposition frames that enable adaptivity and also, in contrast to many adaptive analysis systems, admit the property of fast overlap-add reconstruction. Several properties of this family are proved, and specific examples of adaptation criteria in the context of sparse audio processing are discussed.
Random encoding for robust recovery and channel identification.
Authors: Mantzel William E. , Asif M. Salman , Romberg Justin K.
Published: March 2010

By encoding a signal in a randomly chosen subspace before transmission, this transmitted signal proves robust to sparse errors in the channel. In this talk, we will further demonstrate the robustness of such signals to unknown convolutive channels. In particular, we show that if the channel is not especially resonant at any given frequency (e.g., the channel is sparse or random), we are able to simultaneously recover both the transmitted signal and the channel characteristics by solving a rank minimization in X, the rank-1 outer product of the two unknown vectors, subject to the receiver observations. We demonstrate favorable simulated performance for sparse and random channels. Using a parallel approach to classical compressed sensing theory, we prove a restricted isometry property about our linear operator that guarantees a high probability of recovery when the number of observations is at least linear with the dimension of the message and the length of the channel.
The singing shoebox: A $5 loudspeaker project.
Authors: Porter Scott P. , Domme Daniel J. , Whalen Jeffrey S.
Published: March 2010

Moving-coil loudspeakers typify the interdisciplinary nature of acoustics. In order to reproduce sound, these devices employ principles of electricity, magnetism, mechanics, and acoustics. The widespread use of loudspeakers has made them familiar to students and thus a valuable opportunity to introduce students to acoustics. In this paper, the authors demonstrate a loudspeaker-enclosure system that is easily built from scratch. The system is mostly constructed from common household supplies, making it low-cost and accessible to a wide audience. In addition, this project is well-suited for use by the K-12 educator as the content can be scaled to fit a variety of different academic levels. To this end, the speaker’s design and construction will be presented and its relevance as an educational demonstration discussed. Finally, the loudspeaker will be auditioned and its performance demonstrated.
Longitudinal wave demonstrations.
Authors: Swearingen Michelle E.
Published: March 2010

In a wave, something always moves back and forth. A longitudinal wave is one that travels along the direction of propagation. In this demonstration, two different devices will be used to illustrate longitudinal propagation. An aluminum bar is used to produce transverse waves. A slinky will be used to visually show longitudinal propagation along the slinky. Finally, the aluminum bar is again used to show differences in longitudinal and transverse wave propagations.
Experiment on beats.
Authors: Sen Gupta Ananya
Published: March 2010

When two sounds of nearly the same frequency get together they will alternately add up or cancel out. If they start out together, after a while they will no longer be together, and the peak of the one will meet a trough of the other and they will cancel. The resulting fluctuations are known as beats. The beat frequency is just the difference of the two frequencies. The students will observe and experiment with beats generated by sounding an 880 tuning fork at the same time as an 883 tuning fork.
The tin-can telephone: An example of sound propagation and communication for Project Listen Up.
Authors: Sagers Jason D. , McNeese Andrew R. , Wilson Preston S.
Published: March 2010

The tin-can telephone can be used to illustrate the basic concepts of sound waves and sound-structure interaction. It can also be used to illustrate advanced concepts of frequency response and speech intelligibility in acoustic communications. For the proposed demonstration, students will construct a tin-can telephone from household materials and observe its performance from a variety of acoustic tests. Students will observe sound transmission and discover that some sounds are transmitted with greater clarity than others. A measured frequency response function for several tin-can telephones constructed from different materials will be provided to the student to illustrate the concept of frequency response and speech intelligibility.
Doppler effect.
Authors: Ballard Megan S.
Published: March 2010

The Doppler effect describes the change in frequency observed for a moving source and/or receiver. A common example of the Doppler effect involves a moving vehicle sounding a siren or horn as it approaches, passes, and recedes from an observer. The observed frequency (compared to the emitted frequency) is higher during the approach, is identical at the instant of passing by, and is lower during the recession. In this presentation, the Doppler Effect is demonstrated using a buzzer embedded in a Nerf ball. A difference in pitch can be heard when the ball is thrown to or from an individual. A second demonstration involves twirling a tuning fork from an attached string. An increase/decrease in frequency can be heard as the tuning fork moves toward/away from an observer.
Listen up and get involved: Standing waves—The unbalanced motor and musical string.
Authors: Harght Pamela J.
Published: March 2010

The experiments that will be demonstrated are Standing Waves—The Unbalanced Motor and Standing Waves—Musical String. The unbalanced motor experiment involves a small electric motor that provides tension in the string. Students will observe the effect of holding the string and slowly sliding their hand toward the unbalanced motor. For the musical string experiment, students will observe musical intervals (do-me, do-sol, do-do, etc.) with a tensioned piano string and the science behind musical notes.
The energy flow for a spherical acoustic lens: Experimental results avoiding interference effects.
Authors: Parker Kendez C. , Dean Cleon E.
Published: March 2010

A simple classroom demonstration consists of a weather balloon filled with carbon dioxide, a sound source, and a microphone. Since the speed of sound is slower in carbon dioxide than in air at room temperature and pressure, the balloon acts as a positive spherical acoustic lens. Preliminary experimental results have been presented previously [C. E. Dean and J. P. Braselton, “The energy flow for a spherical acoustic lens: ray and wave methods vs. experiment.,” J. Acoust. Soc. Am. 125, 2627 (2009)]. The possibility of interference effects from the reflection of sound off surfaces was brought up in the ensuing discussion. The current results have been measured in a way that minimizes the effect of interference due to reflections off walls, floor, or other surfaces.
Standing waves on a vibrating string.
Authors: Ruggles Dorea R.
Published: March 2010

Most sounds are made up of many waves added together. These waves, called harmonics, are all related to each other because their frequencies are integer multiples of the lowest frequency, the fundamental. Adding together different amounts of each harmonic is part of what makes different sounds unique. The individual harmonics of a vibrating string are easy to see, one at a time, by creating a standing wave on the string and adjusting the driving frequency. The frequency where the fundamental, one-looped standing wave appears on the string depends on the string’s length, mass, and tension, but if these factors are all kept constant while the driving frequency is increased, a new loop will be added to the standing wave for each multiple of the original frequency. This is an exciting way to see waves, observe their properties, and really understand how frequency, wavelength, and other properties are all interrelated.
Speaker coverage in active acoustic music practice rooms.
Authors: Freiheit Ronald
Published: March 2010

Larger music practice rooms (>25 m3) present unique challenges compared to smaller, traditional practice rooms (6–12 m3) when employing active acoustics technology and integrated digital recording. An experiment was conducted comparing a ceiling array of 32 speakers in a large music practice room (5.3×5.7×2.7 m3, 81 m3) with that of eight speakers located in corners of that room (one at the top and one at the bottom in each corner facing parallel to the walls). The goal was to determine which speaker configuration would be the most effective for creating even sound field coverage and uniform frequency response. Data were collected for both seated and standing positions in the room from a matrix of 42 locations. Frequencies from 40 Hz to 8 kHz were plotted for analysis. The data were compared to the qualitative preferences expressed by a number of musicians using the rooms for both practice sessions (with the active acoustics enabled) and listening to the playback of recorded practice sessions.