Spatial Manipulation Research Articles

Visually precise, low-damage, single-cell spatial manipulation with single-pixel resolution.

The analysis of single living cells, including intracellular delivery and extraction, is essential for monitoring their dynamic biochemical processes and exploring intracellular heterogeneity. However, owing to the 2D view in bright-field microscopy and optical distortions caused by the cell shape and the variation in the refractive index both inside and around the cells, achieving spatially undistorted imaging for high-precision manipulation within a cell is challenging. Here, an accurate and visual system is developed for single-cell spatial manipulation by correcting the aberration for simultaneous bright-field triple-view imaging. Stereo information from the triple view enables higher spatial resolution that facilitates the precise manipulation of single cells. In the bright field, we resolved the spatial locations of subcellular structures of a single cell suspended in a medium and measured the random spatial rotation angle of the cell with a precision of ±5°. Furthermore, we demonstrated the visual manipulation of a probe to an arbitrary spatial point of a cell with an accuracy of <1 pixel. This novel system is more accurate and less destructive for subcellular content extraction and drug delivery.

Photothermal slippery surfaces towards spatial droplet manipulation

Spatial manipulation of various droplets and programmable droplet storage were achieved on a photothermal slippery surface.

Kinesthetic Metaphors for Precise Spatial Manipulation: A Study of Object Rotation

AbstractIn this article, we report on our investigation of kinesthetic feedback as a means to provide precision, accuracy, and mitigation of arm fatigue in spatial manipulation tasks. Most works on spatial manipulation discuss the use of haptics (kinesthetic/force and tactile) primarily as a means to offer physical realism in spatial user interfaces (SUIs). Our work offers a new perspective in terms of how force-feedback can promote precise manipulations in spatial interactions to aid manual labor, controllability, and precision. To demonstrate this, we develop, implement, and evaluate three new haptics-enabled interaction techniques (kinesthetic metaphors) for precise rotation of 3D objects. The quantitative and qualitative analyses of experiments reveal that the addition of force-feedback improves precision for each of the rotation techniques. Self-reported user feedback further exposes a novel aspect of kinesthetic manipulation in its ability to mitigate arm fatigue for close-range spatial manipulation tasks.

Three-dimensional nonlinear optical holograms

The three-dimensional holography technique offers an efficient and convenient tool for storing depth information of the object and provides more realistic images compared to the two-dimensional case, which has been widely used in the fields of optical tweezers, image encryption, and optical microscopy. However, such a three-dimensional nonlinear holography technique is still lacking in the field of nonlinear optics. Here, we demonstrate the realization of three-dimensional nonlinear optical holograms. Without loss of generality, a second-order nonlinearity is used in our experiment and the generated second harmonic with multiplane patterns at different depths is dynamically realized. This study opens up the field of three-dimensional spatial nonlinear harmonic manipulation and may have applications in all-optical wave-band three-dimensional optical imaging, parallel micromachining, holographic displays, and so on.

An immersive educational tool for dental implant placement: A study on user acceptance

BackgroundTools for training and education of dental students can improve their ability to perform technical procedures such as dental implant placement. Shortage of training can negatively affect dental implantologists’ performance during intraoperative procedures, resulting in lack of surgical precision and, consequently, inadequate implant placement, which may lead to unsuccessful implant supported restorations or other complications. ObjectiveWe designed and developed IMMPLANT a virtual reality educational tool to assist implant placement learning, which allows users to freely manipulate 3D dental models (e.g., a simulated patient's mandible and implant) with their dominant hand while operating a touchscreen device to assist 3D manipulation. MethodsThe proposed virtual reality tool combines an immersive head-mounted display, a small hand tracking device and a smartphone that are all connected to a laptop. The operator's dominant hand is tracked to quickly and coarsely manipulate either the 3D dental model or the virtual implant, while the non-dominant hand holds a smartphone converted into a controller to assist button activation and a greater input precision for 3D implant positioning and inclination. We evaluated IMMPLANT's usability and acceptance during training sessions with 16 dental professionals. ResultsThe conducted user acceptance study revealed that IMMPLANT constitutes a versatile, portable, and complementary tool to assist implant placement learning, as it promotes immersive visualization and spatial manipulation of 3D dental anatomy. ConclusionsIMMPLANT is a promising virtual reality tool to assist student learning and 3D dental visualization for implant placement education. IMMPLANT may also be easily incorporated into training programs for dental students.

Integrated sensor networks with error correction for multiplexed particle tracking in microfluidic chips

Spatial manipulation of suspended cells based on their properties is an essential part of numerous microfluidic assays. To further read and analyze the manipulation result, a microscopy system is typically required, which, however, increases the cost and reduces the portability of the entire system. As an alternative, a network of integrated Coulter sensors, distributed over a microfluidic chip, provide rapid and reliable detection of spatially-manipulated cells. Code-multiplexing of distributed Coulter sensors enables simplification of such integration by offloading the hardware complexity into advanced signal processing techniques that are needed to interpret the coded sensor outputs. In this work, we combine code-multiplexed Coulter sensor networks with an error-correction technique, a strategy typically used in telecommunication systems for controlling errors in data over unreliable communication channels. Specifically, we include redundancy in the physical sensor design to alleviate the ambiguity in the signal-decoding process, so that interfering sensor signals due to coincidently-detected cells can be resolved reliably. The presented sensor technology not only tracks the spatiotemporal state of cells under test but also measures their sizes and flow speeds. To demonstrate the sensor concept experimentally, we fabricated a microfluidic device with 10 distributed Coulter sensors designed to produce distinct signal waveforms and performed experiments with suspended human cancer cells to characterize the performance of the sensor platform.

Closer to the Heart, Closer to the Mind: Using Psychological Distance to Communicate a Measles Outbreak

Psychological distance can influence a variety of risk-related perceptions and behaviors. This study (N = 205) examines the effect of spatial distance manipulation on emotions, risk perception, and behavioral intention following a recent measles outbreak in the United States. Results indicate that experimentally induced spatial distance influences emotional intensity, which affects psychological distance perception. Perceived distance subsequently influences risk perception, while emotions influence information engagement and support for mandatory vaccination.

Object selection and scaling using multimodal interaction in mixed reality

Mixed Reality (MR) is the next evolution of human interacting with the computer as MR has the ability to combine the physical environment and digital environment and making them coexist with each other. Interaction is still a huge research area in Augmented Reality (AR) but very less in MR, this is due to current advanced MR display techniques still not robust and intuitive enough to let the user to naturally interact with 3D content. New techniques on user interaction have been widely studied, the advanced technique in interaction when the system able to invoke more than one input modalities. Multimodal interaction undertakes to deliver intuitive multiple objects manipulation with gestures. This paper discusses the multimodal interaction technique using gesture and speech which the proposed experimental setup to implement multimodal in the MR interface. The real hand gesture is combined with speech inputs in MR to perform spatial object manipulations. The paper explains the implementation stage that involves interaction using gesture and speech inputs to enhance user experience in MR workspace. After acquiring gesture input and speech commands, spatial manipulation for selection and scaling using multimodal interaction has been invoked, and this paper ends with a discussion.

On the relationship between trait autobiographical episodic memory and spatial navigation.

Influential research has focused on identifying the common neural and behavioural substrates underlying episodic memory (the re-experiencing of specific details from past experiences) and spatial cognition, with some theories proposing that these are supported by the same mechanisms. However, the similarities and differences between these two forms of memory in humans require further specification. We used an individual-differences approach based on self-reported survey data collected in a large online study (n = 7,487), focusing on autobiographical episodic memory and spatial navigation and their relationship to object and spatial imagery abilities. Multivariate analyses replicated prior findings that autobiographical episodic memory abilities dissociated from spatial navigational abilities. Considering imagery, episodic autobiographical memory overlapped with imagery of objects, whereas spatial navigation overlapped with a tendency to focus on spatial schematics and manipulation. These results suggest that trait episodic autobiographical memory and spatial navigation correspond to distinct mental processes.

Underwater Mobile Manipulation: A Soft Arm on a Benthic Legged Robot

Robotic systems that can explore the sea floor, collect marine samples, gather shallow water refuse, and perform other underwater tasks are interesting and important in several fields, from biology and ecology to off-shore industry. In this article, we present a robotic platform that is, to our knowledge, the first to combine benthic legged locomotion and soft continuum manipulation to perform real-world underwater mission-like experiments. We experimentally exploit inverse kinematics for spatial manipulation in a laboratory environment and then examine the robot's workspace extensibility, force, energy consumption, and grasping ability in different undersea scenarios.

Collagen XI regulates the acquisition of collagen fibril structure, organization and functional properties in tendon

Collagen XI is a fibril-forming collagen that regulates collagen fibrillogenesis. Collagen XI is normally associated with collagen II-containing tissues such as cartilage, but it also is expressed broadly during development in collagen I-containing tissues, including tendons. The goals of this study are to define the roles of collagen XI in regulation of tendon fibrillar structure and the relationship to function. A conditional Col11a1-null mouse model was created to permit the spatial and temporal manipulation of Col11a1 expression. We hypothesize that collagen XI functions to regulate fibril assembly, organization and, therefore, tendon function. Previous work using cho mice with ablated Col11a1 alleles supported roles for collagen XI in tendon fibril assembly. Homozygous cho/cho mice have a perinatal lethal phenotype that limited the studies. To circumvent this, a conditional Col11a1flox/flox mouse model was created where exon 3 was flanked with loxP sites. Breeding with Scleraxis-Cre (Scx-Cre) mice yielded a tendon-specific Col11a1-null mouse line, Col11a1Δten/Δten. Col11a1flox/flox mice had no phenotype compared to wild type C57BL/6 mice and other control mice, e.g., Col11a1flox/flox and Scx-Cre. Col11a1flox/flox mice expressed Col11a1 mRNA at levels comparable to wild type and Scx-Cre mice. In contrast, in Col11a1Δten/Δten mice, Col11a1 mRNA expression decreased to baseline in flexor digitorum longus tendons (FDL). Collagen XI protein expression was absent in Col11a1Δten/Δten FDLs, and at ~50% in Col11a1+/Δten compared to controls. Phenotypically, Col11a1Δten/Δten mice had significantly decreased body weights (p < 0.001), grip strengths (p < 0.001), and with age developed gait impairment becoming hypomobile. In the absence of Col11a1, the tendon collagen fibrillar matrix was abnormal when analyzed using transmission electron microscopy. Reducing Col11a1 and, therefore collagen XI content, resulted in abnormal fibril structure, loss of normal fibril diameter control with a significant shift to small diameters and disrupted parallel alignment of fibrils. These alterations in matrix structure were observed in developing (day 4), maturing (day 30) and mature (day 60) mice. Altering the time of knockdown using inducible I-Col11a1−/− mice indicated that the primary regulatory foci for collagen XI was in development. In mature Col11a1Δten/Δten FDLs a significant decrease in the biomechanical properties was observed. The decrease in maximum stress and modulus suggest that fundamental differences in the material properties in the absence of Col11a1 expression underlie the mechanical deficiencies. These data demonstrate an essential role for collagen XI in regulation of tendon fibril assembly and organization occurring primarily during development.

Application of generalized Bloch method: Strain engineering of low dimensional materials through inhomogeneous strains

Due to their special structural morphologies, low dimensional materials are in nanometer scale in zero, one or two dimensions. This feature offers them superior structural flexibility. This characteristic, together with their excellent electronic property response to mechanical deformation, makes strain engineering an important way to optimize the physical properties of materials. Because in low dimension, structural deformations are usually inhomogeneous, the standard electronic and phonon calculation methods formulated via translation under the periodic boundary conditions encounter fundamental difficulties. A fresh approach in this aspect is called for rapidly. In this paper, the essential idea of the generalized Bloch method is introduced, in the context of a tight-binding treatment of electrons. This special method makes use of the helical symmetry and rotational symmetry to deal with the two fundamental non-uniform structural deformations, i.e., torsion and bending. In this way, the atomistic simulation of the deformed structures can still be carried out through a relatively small repeating cell. Such treatment enables the realistic atomistic quantum mechanical simulations in a viable manner. In practice, this new method is implemented into the so-called density-functional tight-binding (DFTB) calculation, an approach widely used in the material computation today. We note that the utility of DFTB brings us several benefits. First of all, the self-consistent field improves the calculation accuracy to be compatible with first-principles calculations. Next, the capability to deal with spin freedoms of DFTB enables us to study the strain tunable properties of spin-polarized electronic states. We illustrate the application of the generalized Bloch method with several examples that can be categorized into “strain tunable electronic properties”, “spatial manipulation of dopants in semiconductor nanowires”, and “strain engineering of phonon properties”. We also have a vision that the generalized Bloch method shall have important application in more areas. Studies of twist bilayers of two-dimensional materials are one of the focuses of the current condensed matter physics research. However, due to the twist induced lattice mismatch, a twisted bilayer is often of a unit cell containing a huge number of atoms. This makes direct realistic atomistic simulations difficult. We indicate that the calculation can be simplified by using the generalized Bloch method where the helical symmetry and possible rotational symmetry of the twisted bilayer would be used. Exploring giant flexoelectricity is a growing area of materials science. Different from piezoelectricity, flexoelectricity is by definition the linear response of polarization to the strain gradient. Usually, in the actual experimental studies, the strain gradient of materials is generated by applying the bending deformation to the slab. This fact indicates that the generalized Bloch method can be used to simulate such systems. In today’s semiconductor technology, the design of flexible electronic devices is an important development field. The low dimensional materials are natural candidates of flexible systems. Obviously, the generalized Bloch method will also play an important role in this aspect. Our recent work has realized the phonon calculation for low-dimensional structures of helical and rotational symmetries based on the electronic structure calculation with the generalized Bloch method. This functionality will expand the application scope of the generalized Bloch method, making it possible to study the strain modulation of thermal properties in low-dimensional systems with inhomogeneous strain patterns.

Rabi oscillations of azimuthons in weakly nonlinear waveguides

Rabi oscillation, an inter-band oscillation, depicts the periodic flopping between two states that belong to different energy levels in the presence of an oscillatory driving field. In photonics, Rabi oscillation can be mimicked by applying a weak longitudinal periodic modulation to the refractive index change of the system. However, the Rabi oscillation of nonlinear states has yet to be discussed. We report Rabi oscillations of azimuthons---spatially modulated vortex solitons---in weakly nonlinear waveguides with different symmetries, both numerically and theoretically. The period of Rabi oscillation can be determined by applying the coupled mode theory, which largely depends on the modulation strength. Whether the Rabi oscillation between two states can be obtained or not is determined by the spatial symmetry of the azimuthons and the modulating potential. In this paper we succeeded in obtaining the Rabi oscillation of azimuthons in the weakly nonlinear waveguides with different symmetries. Our results not only enrich the Rabi oscillation phenomena, but also provide a new avenue in the study of pattern formation and spatial field manipulation in nonlinear optical systems.

Spatial Attention and Temporal Expectation Exert Differential Effects on Visual and Auditory Discrimination.

Anticipation of an impending stimulus shapes the state of the sensory systems, optimizing neural and behavioral responses. Here, we studied the role of brain oscillations in mediating spatial and temporal anticipations. Because spatial attention and temporal expectation are often associated with visual and auditory processing, respectively, we directly contrasted the visual and auditory modalities and asked whether these anticipatory mechanisms are similar in both domains. We recorded the magnetoencephalogram in healthy human participants performing an auditory and visual target discrimination task, in which cross-modal cues provided both temporal and spatial information with regard to upcoming stimulus presentation. Motivated by prior findings, we were specifically interested in delta (1-3 Hz) and alpha (8-13 Hz) band oscillatory state in anticipation of target presentation and their impact on task performance. Our findings support the view that spatial attention has a stronger effect in the visual domain, whereas temporal expectation effects are more prominent in the auditory domain. For the spatial attention manipulation, we found a typical pattern of alpha lateralization in the visual system, which correlated with response speed. Providing a rhythmic temporal cue led to increased postcue synchronization of low-frequency rhythms, although this effect was more broadband in nature, suggesting a general phase reset rather than frequency-specific neural entrainment. In addition, we observed delta-band synchronization with a frontal topography, which correlated with performance, especially in the auditory task. Combined, these findings suggest that spatial and temporal anticipations operate via a top-down modulation of the power and phase of low-frequency oscillations, respectively.

Robot-assisted ultrasound navigation platform for 3D HIFU treatment planning: Initial evaluation for conformal interstitial ablation

Interstitial Ultrasound-guided High Intensity Focused Ultrasound (USgHIFU) therapy has the potential to deliver ablative treatments which conform to the target tumor. In this study, a robot-assisted US-navigation platform has been developed for 3D US guidance and planning of conformal HIFU ablations. The platform was used to evaluate a conformal therapeutic strategy associated with an interstitial dual-mode USgHIFU catheter prototype (64 elements linear-array, measured central frequency f = 6.5 MHz), developed for the treatment of HepatoCellular Carcinoma (HCC). The platform included a 3D navigation environment communicating in real-time with an open research dual-mode US scanner/HIFU generator and a robotic arm, on which the USgHIFU catheter was mounted. 3D US-navigation was evaluated in vitro for guiding and planning conformal HIFU ablations using a tumor-mimic model in porcine liver. Tumor-mimic volumes were then used as targets for evaluating conformal HIFU treatment planning in simulation. Height tumor-mimics (ovoid- or disc-shaped, sizes: 3–29 cm3) were created and visualized in liver using interstitial 2D US imaging. Robot-assisted spatial manipulation of these images and real-time 3D navigation allowed reconstructions of 3D B-mode US images for accurate tumor-mimic volume estimation (relative error: 4 ± 5%). Sectorial and full-revolution HIFU scanning (angular sectors: 88–360°) could both result in conformal ablations of the tumor volumes, as soon as their radii remained ≤ 24 mm. The presented US navigation-guided HIFU procedure demonstrated advantages for developing conformal interstitial therapies in standard operative rooms. Moreover, the modularity of the developed platform makes it potentially useful for developing other HIFU approaches.

Useful Caged Compounds for Cell Physiology.

Light has been instrumental in the study of living cells since its use helped in their discovery in the late 17th century. Further, combining chemical technology with light microscopy was an essential part of the Nobel Prize for Physiology in 1906. Such landmark scientific findings involved passive observation of cells. However, over the past 50 years, a "second use" of light has emerged in cell physiology, namely one of rational control. The seminal method for this emerged in late 1970s with the invention of caged compounds. This was the point when "caged compounds" were defined as optical probes in which the active functionality of a physiological signaling molecule was blocked with a photochemical protecting group. Caged compounds are analogous to prodrugs; in both, the activity of the effector is latent. However, caged compounds, unlike prodrugs, use a trigger that confers the power of full temporal and spatial manipulation of the effects of release of its latent biological cargo. Light is distinct because it is bio-orthogonal, passes through living tissue (even into the cell interior), and initiates rapid release of the "caged" biomolecule. Further, because light can be directed to broad areas or focused to small points, caged compounds offer an array of timing scenarios for physiologists to dissect virtually any type of cellular process.The collaborative interaction between chemists and physiologists plays a fundamental role in the development of caged compounds. First, the physiologists must define the problem to be addressed; then, with the help of chemists, decide if a caged compound would be useful. For this, structure-activity relationships of the potential optical probe and receptor must be determined. If rational targets seem feasible, synthetic organic chemistry is used to make the caged compound. The crucial property of prephotolysis bio-inertness relies on physiological or biochemical assays. Second, detailed optical characterization of the caged compound requires the skill of photochemists because the rate and efficiency of uncaging are also crucial properties for a useful caged compound. Often, these studies reveal limitations in the caged compound which has been developed; thus, chemists and physiologists use their abilities for iterative development of even more powerful optical probes. A similar dynamic will be familiar to scientists in the pharmaceutical industry. Therefore, caged compound development provides an excellent training framework for (young) chemists both intellectually and professionally. In this Account, I draw on my long experience in the field of making useful caged compounds for cell physiology by showing how each probe I have developed has been defined by an important physiological problem. Fundamental to this process has been my initial training by the pioneers in aromatic photochemistry, Derek Bryce-Smith and Andrew Gilbert. I discuss making a range of "caged calcium" probes, ones which went on to be the most widely used of all caged compounds. Then, I describe the development of caged neurotransmitters for two-photon uncaging microscopy. Finally, I survey recent work on making new photochemical protecting groups for wavelength orthogonal, two-color, and ultraefficient two-photon uncaging.

The politics of time in early Chinese translation of Western modernity

ABSTRACT Western modernity, the darker side of which is global coloniality that is dependent upon translation, is essentially a culture of time. While the temporality of modernity has been well analysed and explained in the West, it remains largely unknown how the politics of time has been operating in and through translation in the Rest. This article attempts to explore ways in which the politics of time is played out in early-modern textual and extratextual translation of modernity in China, whose traditional conception of time and vision of human life encoded in its language differs from those of the West represented by Greco-Roman and Christian traditions. By examining a few cases in the Jesuits’ translational activities in the later Ming and early Qing dynasties, it demonstrates how modernity’s temporal–spatial construct asserted itself in China by way of biblical chronologization, and spatial and textual manipulation in geographic, philosophical, and science translation, through which modernity has, in time, changed China.

A review on microfluidics manipulation of the extracellular chemical microenvironment and its emerging application to cell analysis

Spatiotemporal manipulation of extracellular chemical environments with simultaneous monitoring of cellular responses plays an essential role in exploring fundamental biological processes and expands our understanding of underlying mechanisms. Despite the rapid progress and promising successes in manipulation strategies, many challenges remain due to the small size of cells and the rapid diffusion of chemical molecules. Fortunately, emerging microfluidic technology has become a powerful approach for precisely controlling the extracellular chemical microenvironment, which benefits from its integration capacity, automation, and high-throughput capability, as well as its high resolution down to submicron. Here, we summarize recent advances in microfluidics manipulation of the extracellular chemical microenvironment, including the following aspects: i) Spatial manipulation of chemical microenvironments realized by convection flow-, diffusion-, and droplet-based microfluidics, and surface chemical modification; ii) Temporal manipulation of chemical microenvironments enabled by flow switching/shifting, moving/flowing cells across laminar flows, integrated microvalves/pumps, and droplet manipulation; iii) Spatiotemporal manipulation of chemical microenvironments implemented by a coupling strategy and open-space microfluidics; and iv) High-throughput manipulation of chemical microenvironments. Finally, we briefly present typical applications of the above-mentioned technical advances in cell-based analyses including cell migration, cell signaling, cell differentiation, multicellular analysis, and drug screening. We further discuss the future improvement of microfluidics manipulation of extracellular chemical microenvironments to fulfill the needs of biological and biomedical research and applications.

Enhance CO2-to-C2+ products yield through spatial management of CO transport in Cu/ZnO tandem electrodes

The electrochemical reduction of CO2 into C2+ products is a promising route to store renewable electricity in the form of chemical energy. The current barrier to this technique is the low efficiency of C-C coupling through dimerization of adsorbed *CO or coupling of *CO with its hydrogenated derivatives over the Cu catalyst. Tandem catalysts, which integrate Cu with another CO-generation catalyst (e.g., ZnO), can enhance the C-C coupling kinetics by increasing the local concentration of the key intermediate of CO. However, the degree of enhancement is strongly dependent on the spatial manipulation of supplementary CO transport. Herein, inspired by the reactant species concentration profile in a plug flow reactor, Cu/ZnO tandem electrodes are designed by spatially adding a ZnO catalyst layer on top of the Cu catalyst layer, in which the ZnO catalyst layer fed CO concentration progressively decreases over the Cu catalyst layer. Such a spatial management of CO transport dramatically increases the CO utilization efficiency, leading to an enhancement of Faradaic efficiency and partial current density of C2+ products by 1.2 and 3.4 times, respectively, compared to the bare Cu electrode, while by 1.3 and 1.8 times, respectively, compared to the Cu&ZnO mixed electrode.

Spatial Release from Masking Using Clinical Corpora: Sentence Recognition in a Colocated or Spatially Separated Speech Masker.

Speech recognition in complex multisource environments is challenging, particularly for listeners with hearing loss. One source of difficulty is the reduced ability of listeners with hearing loss to benefit from spatial separation of the target and masker, an effect called spatial release from masking (SRM). Despite the prevalence of complex multisource environments in everyday life, SRM is not routinely evaluated in the audiology clinic. The purpose of this study was to demonstrate the feasibility of assessing SRM in adults using widely available tests of speech-in-speech recognition that can be conducted using standard clinical equipment. Participants were 22 young adults with normal hearing. The task was masked sentence recognition, using each of five clinically available corpora with speech maskers. The target always sounded like it originated from directly in front of the listener, and the masker either sounded like it originated from the front (colocated with the target) or from the side (separated from the target). In the real spatial manipulation conditions, source location was manipulated by routing the target and masker to either a single speaker or to two speakers: one directly in front of the participant, and one mounted in an adjacent corner, 90° to the right. In the perceived spatial separation conditions, the target and masker were presented from both speakers with delays that made them sound as if they were either colocated or separated. With real spatial manipulations, the mean SRM ranged from 7.1 to 11.4 dB, depending on the speech corpus. With perceived spatial manipulations, the mean SRM ranged from 1.8 to 3.1 dB. Whereas real separation improves the signal-to-noise ratio in the ear contralateral to the masker, SRM in the perceived spatial separation conditions is based solely on interaural timing cues. The finding of robust SRM with widely available speech corpora supports the feasibility of measuring this important aspect of hearing in the audiology clinic. The finding of a small but significant SRM in the perceived spatial separation conditions suggests that modified materials could be used to evaluate the use of interaural timing cues specifically.