Sound Array Research Articles

Dimension-reduced generalized likelihood ratio detection based on sampling of normal modes in deep ocean

In this paper, two generalized likelihood ratio (GLR) detectors are presented for the case of multiple snapshots of test data to detect the presence of an underwater acoustic source in the deep ocean. The two GLR detectors are termed the eigenvalue detector (EVD) and the constant false alarm rate eigenvalue detector (CFAR EVD), respectively. Theoretical analysis and numerical results show that for a given input signal-to-noise ratio (SNR) of the array, the GLR detectors achieve higher output SNRs when the spatial dimension of test data decreases. To further enhance the detection performances of the GLR detectors, we propose a dimension-reduced (DR-GLR) method based on array sampling of modal information. This DR-GLR method combines the characteristics of sound propagation and array receiving. According to normal mode theory, acoustic signals emitted from the acoustic source lie in the modal space spanned by the sampled modal information of the array. Resulting from the restriction of the array size, it often occurs in deep ocean when the dimension of " effective modal subspace” is less than that of the test data which is equivalent to the number of hydrophones. Based on this phenomenon, we reconstruct the modal information by merely retaining the " effective modal subspace” to formulate the dimension reduction matrix. The DR-GLR test statistics is deduced by employing the dimension reduction matrix when using the vertical linear array (VLA) and the horizontal linear array (HLA), respectively. The DR-GLR detectors when using an HLA require more computational amount than when using a VLA. Simulation experiments are conducted to analyze the detection performances of the two GLR detectors, and verify the performance improvement effects of DR-GLR detectors. The numerical results show that the CFAR EVD presents good robustness to the uncertainty of the noise power and the DR-GLR detectors outperform the GLR detectors in detection performance. It also turns out the acoustic signals received by the HLA lie in a lower-dimensional " effective modal subspace” than by the VLA, and thus when using an HLA the DR-GLR detectors present higher detection probabilities than using a VLA. Moreover, the smaller the dimension of the " effective modal subspace”, the better the performance improvement of the DR-GLR detectors will be. The dimension of the " effective modal subspace” increases with hydrophone spacing and/or the source frequency increasing.

Meridional march of diurnal rainfall over Jakarta, Indonesia, observed with a C-band Doppler radar: an overview of the HARIMAU2010 campaign

This paper presents an overview of the HARIMAU2010 campaign focusing on convective activity with the diurnal rainfall meridional march (DRMM) over Jakarta, which is located on the northern coast of Jawa Island of the Indonesian maritime continent (IMC), based on 1-month intensive observations by a C-band Doppler radar and multi-point atmospheric sounding array conducted during 16 January–14 February 2010. The campaign period corresponded to a phase after large-scale Madden–Julian oscillation (MJO) active convections passed over Jakarta (MJO inactive phase). The cross-equatorial northerly surge (CENS) intruded into the Jawa Sea with a cold tongue (CT) of sea surface temperature (SST) in the beginning of the period (CENS active period: 16–26 January), and then, it started to retreat (transition period: 27 January–05 February); afterward, only a few signs of it were apparent (CENS inactive period: 06–14 February). The observational results showed that (1) rainfall over Jakarta has the nature of DRMM during the MJO inactive phase at least, (2) the DRMM is likely driven primarily by “land-breeze”-like local meridional circulation, and (3) the meridional spatiotemporal variation of rainfall over Jakarta is thus controlled by activities of both the CENS and CT over the Jawa Sea.

The contribution of selective spatial attention to sound detection and sound localization: Evidence from event-related potentials and lateralized alpha oscillations

Auditory selective attention can be directed toward spatial and non-spatial stimulus features. Here, we studied electrophysiological correlates of spatial attention under spatially-specific and purely feature-based demands. Using an auditory search paradigm, in which participants performed a target localization (left versus right) and a target detection task (present versus absent), we investigated whether attentional selection of a relevant sound from a two- or four-sound array necessarily involves the processing of spatial sound information. While the early N2 anterior contralateral component occurred irrespective of task, the subsequent lateralization of alpha power oscillations (8–12 Hz) over parieto-occipital scalp was modulated by the task-relevance of spatial information. Thus, the two correlates appear to reflect differential aspects of attentional orienting: We propose that the N2ac reflects an initial, modality-specific focusing of attention onto a lateralized target, while the subsequent alpha lateralization appears associated with the spatiotopic access to presumably supramodal representations of the sound array.

Searching for auditory targets in external space and in working memory: Electrophysiological mechanisms underlying perceptual and retroactive spatial attention

Attention can be shifted within internal representations maintained in working memory. These retroactive processes are particularly inherent to the processing of auditory information that is especially transient over time and thus, requires us to continuously maintain, attend to, and integrate information in working memory. Using EEG recordings, the present study investigated the neurophysiological mechanisms underlying selective spatial attention in a retroactive as opposed to a perceptual auditory search task. Two kinds of sound stimuli were employed: a horizontal sound array consisting of two natural sounds presented simultaneously in the left and right hemispace and a central single target sound. The target sound was provided either after (retroactive search) or before the presentation of the sound array (perceptual search). In both search conditions, participants completed a sound localization and a sound detection task, indicating the position (left or right) or the presence versus absence (yes or no) of a particular target sound. Analyses revealed a lateralization of alpha power oscillations (8–12 Hz) over parieto-occipital scalp in both perceptual and retroactive sound localization tasks, but not in respective sound detection tasks, suggesting auditory alpha lateralization to be restricted to spatially-specific task demands. The observed asymmetric modulations of alpha power in sound localization are consistent with analogous findings from the visual domain, supporting the supramodal role of alpha oscillations in the deployment of spatial attention. Hence, we conclude that auditory alpha lateralization is a higher-order attention mechanism that operates in perceptual and mnemonic space reflecting the access to a spatially-specific, supramodal response template.

Deployment of a short-term geophysical field survey to monitor acoustic signals associated with the Windsor Hum

The Hum is a widespread phenomenon, reported in many parts of the world. It manifests itself in the form of a hum, rumble and pulsing, often felt as a sensation more than an audible sound. Starting in 2011, residents of Windsor, Ontario, Canada started reporting intermittent low frequency sound, widely referred to as the Hum (and dubbed the Windsor Hum). This report outlines the deployment of a short term geophysical field survey, performed during 2013 in Windsor, Ontario, Canada, aimed at monitoring the airwave signals associated with the Windsor Hum. The summary of the low frequency sound array deployment is presented and discussed.

Locating culture, making soundscapes and activating critical social relations: A case study from Limerick SoundScapes

Abstract Limerick SoundScapes is a sound-mapping project that seeks to critically engage citizens of the multicultural, socially and economically divided post-industrial City of Limerick in the Republic of Ireland. Facilitated by an interdisciplinary team at the local university, citizens from all walks of life are encouraged to traverse the city, using hand-held recorders to capture a vast array of sounds and create soundscapes. Initially, we locate the project within the context of a city currently experiencing a state-sponsored programme of urban regeneration. The project is also understood in terms of top-down and bottom-up cultural initiatives, particularly in relation to Limerick’s designation as National City of Culture 2014. In addition to looking at how Limerick SoundScapes was conceived and realized through a pilot programme in 2013, we focus specifically on two members of two local participating organizations as an example of how the project operates. Through the activities and experiences of these two volunteer recordists, we illustrate how the project is as much (if not more) focused on engagement and building social relations as it is on producing a finished product that seeks to sonically and culturally represent the city. Such projects have the capacity to promote real diversity and a critical and participatory citizenship through shared, creative goals and a dialogic of doing. However, we also show that culture is often understood in a particular way in Limerick, which we argue is to the detriment of investing in bottom-up projects that can potentially build ‘institutional capacity’ and boost ‘civic creativity’.

Non-whistle sounds used in bottlenose dolphin aggressive interactions recorded on digital acoustic tags

Bottlenose dolphins (Tursiops truncatus) produce a wide array of sounds, including clicks for echolocation and whistles for communication, both of which have been studied intensively. However, sounds other than whistles and echolocation clicks have received less attention, probably due to their high variability. These include the class of sounds loosely described as “burst pulses,” which in several studies of dolphins under human care have been linked to aggressive interactions. Few studies have been carried out in the wild, beyond those describing basic acoustic parameters of sounds. Here we use acoustic and movement recording tags (DTAGs) placed simultaneously on both members of pairs of free-ranging bottlenose dolphins in Sarasota Bay, Florida, USA, to investigate acoustic behavior during aggressive interactions between male alliances and female-calf pairs. Using unsupervised clustering and discriminant function analysis on parameters such as frequency content, duration and rise time, we separate three different sound types recorded during aggressive interactions: broadband burst pulses, highly resonant cracks, and low-frequency narrowband quacks. We demonstrate how these different signal types appear to be used in the context of male-to-female aggression and/or male-male coordination. These characterizations may assist researchers analyzing acoustic recordings in assigning behavioral states to animals that are largely out of sight.

Subjective listening tests: Perception and preference of simulated sound fields

Concert hall sound fields were simulated by architecture students and anechoic recordings were convolved to create auralizations in those simulated performance spaces. Then an architectural feature was altered digitally and a second track was auralized. College music students were recruited, tested for hearing loss, and brought to a low-reverberance room with a spatial sound array of 28 mounted speakers. They were asked to identify which of the two simulated tracks they prefer. We compared simulated performance spaces: (1) with four tiers of balconies vs with one tier of balcony; (2) with an over-stage canopy vs without a canopy; (3) with separate balcony boxes vs with a continuous balcony not fragmented by box walls; and (4) with a higher scattering coefficient vs a lower scattering coefficient. Those in the audience will be invited to judge preference between the tracks for themselves. The study will be framed by the extraordinary career arc of Bert Kinzey who engaged architecture students in the study of architectural acoustics at both Virginia Tech and at the University of Florida.

Human listening experiments provide insight into cetacean auditory perception

Odontocete cetaceans produce an array of sounds including echolocation clicks that can be used for object recognition and whistles used primarily for communication. Echoes and whistles contain a multitude of acoustic features, and the salient features used by animals when identifying objects or in social contexts are often difficult to isolate. One method for detecting salient acoustic features is to compare the performance of cetaceans and humans on the same auditory perception tasks. Human listeners can be presented with echoes produced with simulated cetacean clicks or whistle-like stimuli and provide verbal feedback on discriminatory cues. An early human listening study was performed by Au and Martin (1989). Seven studies performed over the past 15 years show that humans perform as well or better than cetacean subjects in a variety of tasks: echoic discrimination of objects varying in size, shape, material, texture, or wall thickness; echoic recognition of objects from various aspect angles; echoic object discrimination using clicks from different cetacean species; and recognition of frequency-modulated whistle-like sounds. Analyzing the error patterns of humans and cetaceans alongside the reported cues reveals processing mechanisms and decision strategies cetaceans may use. This comparative approach sheds light on how cetaceans perceive and represent sounds.

Effect of dry large‐scale vertical motions on initial MJO convective onset

AbstractAnomalies of eastward propagating large‐scale vertical motion with ~30 day variability at Addu City, Maldives, move into the Indian Ocean from the west and are implicated in Madden‐Julian Oscillation (MJO) convective onset. Using ground‐based radar and large‐scale forcing data derived from a sounding array, typical profiles of environmental heating, moisture sink, vertical motion, moisture advection, and Eulerian moisture tendency are computed for periods prior to those during which deep convection is prevalent and those during which moderately deep cumulonimbi do not form into deep clouds. Convection with 3–7 km tops is ubiquitous but present in greater numbers when tropospheric moistening occurs below 600 hPa. Vertical eddy convergence of moisture in shallow to moderately deep clouds is likely responsible for moistening during a 3–7 day long transition period between suppressed and active MJO conditions, although moistening via evaporation of cloud condensate detrained into the environment of such clouds may also be important. Reduction in large‐scale subsidence, associated with a vertical velocity structure that travels with a dry eastward propagating zonal wavenumbers 1–1.5 structure in zonal wind, drives a steepening of the lapse rate below 700 hPa, which supports an increase in moderately deep moist convection. As the moderately deep cumulonimbi moisten the lower troposphere, more deep convection develops, which itself moistens the upper troposphere. Reduction in large‐scale subsidence associated with the eastward propagating feature reinforces the upper tropospheric moistening, helping to then rapidly make the environment conducive to formation of large stratiform precipitation regions, whose heating is critical for MJO maintenance.

Humidity variability revealed by a sounding array and its implications for cloud representation in GCMs

AbstractSubgrid‐scale humidity variability is critical for statistical cloud schemes. The Atmospheric Radiation Measurement (ARM) sounding array, covering a comparable size to a grid box of current global climate models (GCMs), provides estimates of subgrid‐scale humidity variability. Using radiosonde measurements from ARM sounding arrays, humidity variabilities at a tropical and a midlatitude site are analyzed. Normalized moisture variance is small in the lower troposphere but tends to be large in the middle troposphere. Moisture variability dominates relative humidity (RH) variability at the tropical site, but the contribution by temperature variability cannot be ignored at the midlatitude site. Based on the analysis, a simple linear relationship between RH variance and mean is proposed. Cloud schemes assuming Gaussian distributions give comparable cloudiness as those assuming a beta distribution considering both moisture variance and skewness. A probability distribution function scheme assuming a Gaussian distribution of RH has more flexibility than a RH threshold scheme, which tends to overestimate cloudiness in the moist boundary layer over the tropics. Supersaturation with respect to ice needs to be allowed in the upper troposphere over the tropics to reduce the persistent overestimated cloudiness there. Similar comparison results are found from analysis of cloud resolving model simulations. The study suggests that measurements from sounding arrays would be valuable for statistical cloud scheme evaluation and development.

Apply Two Methods to Measure Engine Noise Source Identification

Based on sound intensity and acoustic array methods, noise source identification of an engine is measured at idle condition. The main noise source of intake surface and exhaust surface are determined, also their frequency spectrum analysis. This two kinds of method testing results fundamentally agreed very well, and verify acoustic array method is more simple and easier than sound intensity method.

Technology asPharmakon: The Promise and Perils of the Internet for Foreign Language Education

Globalization and networking technologies have transformed the contexts, means, and uses of foreign language learning. The Internet offers a vast array of texts, films, music, news, information, pedagogical resources, sounds, and images from around the world as well as unprecedented opportunities for direct communication with native speakers in real time. However, the very technology that delivers these materials and interactions can produce subtle mediational effects that can influence how learners evaluate and interpret them. Focusing first on technological mediation broadly, and then on the specific context of desktop videoconferencing in a telecollaboration project, this article outlines the benefits and the potential pitfalls that computer mediation presents for the learning of languages and cultures. Specific attention is given to the question of what it means to mediate the foreign culture through interfaces that are familiar from one's home culture. The principal argument is that the dynamics of online language learning call for a relational pedagogy that focuses on how medium and context interact with language use. The goal of such an approach is to expose students to a broader scope of symbolic inquiry, to connect present text‐making practices with those of the past, and to foster a critical perspective that will prepare young people to understand and shape future language and literacy practices.

An Equipment Fault Sound Location System Design

The location of the sound source is an important technique for equipment failures diagnostic application. This paper design a specific fault sound location system for capturing the specific sound source and determine its orientation. The two functions of sound recognition and location system are combined. The frequency domain characteristics based on similarity calculation method is used to identify the sound signal. The source localization algorithm based on the time delay estimation is used to calculate the time difference of arrival sound signal. By method of combining hardware circuit preprocessing and software design, the orientation of positioning of sound source is determined by the known sound pickup arrays spatial position. The sound location system uses two piece of MCU to achieve its function with simplification efficient algorithm and high accuracy.

Structure and Properties of Madden–Julian Oscillations Deduced from DYNAMO Sounding Arrays

Abstract The kinematic and thermodynamic characteristics of the October and November 2011 Madden–Julian oscillations (MJOs) that occurred over the Indian Ocean during Dynamics of the MJO (DYNAMO) are investigated. Analyses are presented 1) for two primary sounding arrays, where results are independent of model parameterizations, and 2) on larger scales, including the Indian Ocean, using operational and reanalysis data. Mean precipitation during DYNAMO was characterized by maxima in two east–west bands north and south of the equator. This pattern alternated between two bands during the inactive phase of the MJOs and a single rainfall maximum on the equator during the active phases. Precipitation over the northern sounding array (NSA), where the MJO signal was strongest, was significantly modulated by the MJOs, while the southern array experienced more frequent, briefer episodes of rainfall mostly related to ITCZ convection. Over the NSA the MJOs were characterized by gradual moistening of the low to midtroposphere over approximately 2-week periods. The October MJO featured multiple westward-moving, 2-day disturbances whereas the November MJO principally comprised two prominent Kelvin waves. Patterns of moistening, divergence, and vertical motion suggest a stepwise progression of convection, from shallow cumulus to congestus to deep convection. Tilted thermal anomalies in the upper troposphere–lower stratosphere reveal gravity or Kelvin waves excited by the MJO convective envelopes, which modulate the tropopause and contribute to preactive-phase upper-tropospheric moistening. While there is a number of similarities in the characteristics of the two MJOs, there are sufficient differences to warrant caution in generalizing results from these two events.

Investigation of noise sources in high-speed trains

In this paper, the quantification of the external noise sources in high-speed trains is discussed. A thorough understanding of the underlying causes of noise generation in high-speed trains is needed to develop effective noise control measures. However, because high-speed trains produce a complex array of sounds, it is very difficult to determine each individual source of noise. In this study, the delay-and-sum beamforming method, which uses microphone arrays, was used to separate the noise sources and analyze the sound characteristics of high-speed trains. A new microphone array with 96 microphones was designed to measure the noise produced by high-speed trains. Performance verification tests were conducted to ensure the reliability of the results obtained from the array. Then, the system was used to measure the sounds produced by Korean high-speed trains traveling at speeds between 150 and 300 km/h. Sound maps were then produced using the beamforming technique. The study determined that the majority of the noise produced by the high-speed trains originated from the front nose, bogie, pantograph and inter-coach spacing. Finally, the beampower spectra of the aerodynamic noise sources originating in the front nose, pantograph and inter-coach spacing were deduced from frequency conversion. From these results, the aerodynamic noise characteristics of the major sources of noise in high-speed trains were determined.

Simultaneous magnetotelluric and magnetovariation soundings in the western slope of the Voronezh massif

This paper presents the international project KIROVOGRAD studying the geoelectrical stru ct ure of the western slope of the Voronezh Massive in Russia and Ukraine by means of the advanced simultaneous deep electromagnetic sounding array with natural field excitation and geological and geophysical analysis of the nature of the revealed crustal conducting anomalies. We discuss the history, goals, tasks and organizing structure of the project, methodical and technological innov at ions applied, the achieved results and perspective plans. Maps of the most important invariants of magnetotelluric and magnetovariational transfer functions are presented in the area from the Mo s- c ow Syncline to the Dnepr-Donetsk Trough and from Belorussian borders to the railway Moscow-Kharkov. Geoelectrical sections along the series of profiles and maps of sedimentary and crustal conductance obtained from 2D+ and quasi-3D data interpretations are shown. The complex junction of three quasi-linear crustal anomalies - Kirovograd, Kursk and Kirov-Bariatino is demonstrated.

Cage for One: Multiple-Percussion Solo with Soundscape in Three Movements , and: Argoru VIII: For Snare Drum , and: Micro-Concerto: For Percussionist and Mixed Quintet (review)

Reviewed by: Cage for One: Multiple-Percussion Solo with Soundscape in Three Movements, and: Argoru VIII: For Snare Drum, and: Micro-Concerto: For Percussionist and Mixed Quintet Brian Holder Dwayne Corbin . Cage for One: Multiple-Percussion Solo with Soundscape in Three Movements. New York: Henmar Press, sole selling agents C. F. Peters, 2009. [Equipment requirements, p. ii; performer notes, p. iii; program notes, p. iv-v; score, p. 2-13. Compact disc. Pub. no. EP 68290. $25.] Alvin Singleton . Argoru VIII: For Snare Drum. Edited by Peggy Benkeser. Mainz: Schott, 2009. [Pref. in Eng., Ger.; score, p. 1-6. ISBN-10 142348889X, ISBN-13 9781423488897, ISMN M600010561, ISMN-13 9790600010561, pub. no. ED 30023. €20.95.] Steven Mackey . Micro-Concerto: For Percussionist and Mixed Quintet. New York: Hendon Music; Boosey and Hawkes; dist. by Hal Leonard, 2010. [Notes by the composer, p. [i]; score, p. 1-67. ISMN 979-0-051-21302-3, pub. no. HPS 1303. $19.99.] The polymath world of the solo percussionist encompasses a wide array of sounds, devices, techniques, and implements. Such is the nature of this review, which examines three very different publications that task the musical diversity of the modern percussion artist. We will begin with Dwayne Corbin's Cage for One, an electroacoustic multiple-percussion solo, followed by Alvin Singleton's Argoru VIII for solo snare drum, and Steven Mackey's Micro-Concerto for percussion soloist and chamber ensemble. Individually, they embody different aspects of the percussion workload. Together, these new pieces illustrate much of what is current in the world of contemporary percussion composition. Dwayne Corbin won first prize in the 2009 Percussive Arts Society Composition Contest with his Cage for One, a didactic electroacoustic work for solo percussionist and soundscape. It is inspired by the percussion compositions of John Cage (and fittingly published by the C. F. Peters Corporation). The solo is divided into three movements ("Nothing," "Soliloquy," and "Deconstruction"), and requires the use of three Chinese toms, five tin cans, a log drum with two pitches, two "non-Cuban" cowbells, two differently pitched maracas, a riveted Chinese cymbal, a shaker mounted on a foot pedal, ankle bells, five woodblocks, and a sound system (with headphones for the soloist). A compact disc included with the score contains the required soundscape and a recording of the entire work. Corbin presents an inviting score, complete with program notes, performance notes, the obligatory notational guide, mallet suggestions, and a black-and-white photograph of the instrument setup used at the premiere. Specifically, this solo is an exploration of rhythmic and timbral considerations found within the John Cage oeuvre. Corbin writes in his notes: "if a person mastered these rhythms in the context of a solo piece, they would then be able to move to any piece by Cage and perform his rhythms with relative ease, thereby allowing chamber ensembles more time to prepare great musical performances rather than having to focus so much time on simply surviving the complex rhythms" (p. iv). As such, Cage for One has [End Page 667] numerous passages that juxtapose rhythmic groupings and subdivisions. Corbin accomplishes this in a clever way—each movement treats a different kinesthetic concept. The first movement challenges the performer to perform rhythmic ideas while synchronizing with variables found within the soundscape. The second movement involves the polyphonic independence that exists when performing with four mallets while ignoring the soundscape. Finally, the third movement involves four-limb independence, in which the feet are often set in opposition to the hands. Taken all together, this is an effective educational tool for training rhythmic multitasking. The percussion setup evokes Cage's Amores (1943) and Third Construction (1941), while the soundscape utilized in the second movement is based on the principles expressed in Radio Music (1956) and similar compositions. The notation of some of the third movement is also reminiscent of the exterior movements of Living Room Music (1940). The instrumentation is well conceived, but it is unfortunate that Corbin neglects one instrument of the ensemble: the riveted Chinese cymbal. This item sounds only twice in the entire composition (and only then in the last movement). In reading the program notes, this reviewer anticipated a suggestion of...

“Magic Portraits Drawn by the Sun”: New Orleans, Yellow Fever, and the sense(s) of death in Josh Russell’s Yellow Jack

In ways comparable to the horrors of Hurricane Katrina and its aftermath in 2005, the series of yellow fever epidemics that devastated New Orleans through the nineteenth century were also the result, in part, of the city’s geographical position, its unforgiving climate, and the policies of interested parties; the fever’s awful death toll was likewise accompanied by a grotesque array of sights, sounds and smells. This article will focus upon Josh Russell’s 1999 novel Yellow Jack, which provides a complex portrait of the mid-nineteenth-century city, its fever epidemics, and its conflicting narratives. As well as providing an intense fictional encounter with a formative period in New Orleans’s history, Yellow Jack is a sophisticated study of the role of visual imagery in documenting such horrors, whose prose is steeped in the smells and sounds of the time and place. This article, then, will discuss this novel’s intense engagement with the various “senses” of a very particular Southern place.

Basin Shear-Wave Velocities beneath Seattle, Washington, from Noise-Correlation Rayleigh Waves

Tomography with short-period Rayleigh waves, extracted using noise interferometry, can refine S -wave velocity ( V S ) models in urban areas with dense arrays of short-period and broadband instruments. We apply this technique to the Seattle area to develop a new shallow V S model for use in seismic-hazard assessment. Continuous data from the Seismic Hazards in Puget Sound (SHIPS) array and local broadband stations have interstation distances of 90 km or less. This spacing allows us to extract Rayleigh waves with periods between 2 and 10 s that are sensitive to shallow-basin structure. This new V S model for the Seattle basin is constructed using direct observations rather than using P -wave velocity ( V P ) observations and a V P / V S ratio as all previous 3D models at this scale have been constructed. Our results reveal greater detail in the upper 3.5 km than previous models. Earthquake simulations calculated using our new model better predict peak ground velocities (PGV) at periods between 1 and 2 s for two local earthquakes than the previous model used to calculate Seattle’s seismic-hazard map (Frankel et al. , 2007). We collected data from two local earthquakes and ran finite-difference simulations using our new velocity model as well as the previous velocity model used in development of the Seattle seismic-hazard maps to assess how well our model predicts ground motions relative to the previous model. With a recent deployment of Netquakes strong-motion stations by the Pacific Northwest Seismic Network (PNSN) and the U.S. Geological Survey, we are now able to make more comprehensive assessments of the predictions for recent events.