Masking Noise Research Articles

Spread the Word: Enhancing Replicability of Speech Research Through Stimulus Sharing.

The ongoing replication crisis within and beyond psychology has revealed the numerous ways in which flexibility in the research process can affect study outcomes. In speech research, examples of these "researcher degrees of freedom" include the particular syllables, words, or sentences presented; the talkers who produce the stimuli and the instructions given to them; the population tested; whether and how stimuli are matched on amplitude; the type of masking noise used and its presentation level; and many others. In this research note, we argue that even seemingly minor methodological choices have the potential to affect study outcomes. To that end, we present a reanalysis of six existing data sets on spoken word identification in noise to assess how differences in talkers, stimulus processing, masking type, and listeners affect identification accuracy. Our reanalysis revealed relatively low correlations among word identification rates across studies. The data suggest that some of the seemingly innocuous methodological details that differ across studies-details that cannot possibly be reported in text given the idiosyncrasies inherent to speech-introduce unknown variability that may affect replicability of our findings. We therefore argue that publicly sharing stimuli is a crucial step toward improved replicability in speech research. https://doi.org/10.23641/asha.21985907.

Speech privacy through dynamic fundamental frequency matching

The lack of speech privacy is known to be detrimental to one's physical and psychological health. When physical barriers are not feasible to provide this, a masking noise may be implemented to provide speech privacy. Such maskers are most effective when the difference in mean fundamental frequency (F0) between speech and the masker is minimised. Furthermore, noise annoyance is primarily attributed to the loudness and presence of high-pitched components. The present study investigates the effectiveness and annoyance caused by a masker that minimises instantaneous F0 differences. Two seed maskers (pink and babble noise) were used to generate a unique masker for each test sentence read by a variety of speakers. A subjective listening test and annoyance survey were carried out to determine the effects of the dynamically matched masker, a stationary masker at the mean fundamental frequency of each speaker, and the seed masker without F0 processing. The maskers were played at a variety of target to masker ratios. Preliminary results show that the dynamically matched masker is as effective and less annoying than the stationary masker.

Sound masking of residential noise by a birdsong depending on spectral and temporal characteristics

This study aimed to investigate the sound masking according to spectral and temporal characteristics of residential noise and natural sound through auditory experiment. Since there are various types of residential noise sources (maskee) and natural sounds (masker), stimuli to be used for experiment were selected by dividing the sound source groups through the k-means cluster method. The stimuli consisted of a total of 7 maskee including a brown noise, and 7 masker (birdsongs and water sounds). In the auditory experiment, the preference of masker and the annoyance and unpleasantness of single maskee and masker and mixed sources (maskee+masker) were investigated. Result showed that Phoenicurus auroreus and stream-Fast were the highest preference among masker, and masker preference were significantly correlated with masker annoyance. In addition, it was found that impact sound (children jumping and running and piledriver) show relatively higher annoyance than other sound sources. Relative annoyance of mixed sources (maskee+masker) to single maskee was analyzed and masking effect was discussed based on spectral and temporal and the Zwicker's parameters of each sound source.

Unsupervised Representation Learning with Task-Agnostic Feature Masking for Robust End-to-End Speech Recognition

Unsupervised learning-based approaches for training speech vector representations (SVR) have recently been widely applied. While pretrained SVR models excel in relatively clean automatic speech recognition (ASR) tasks, such as those recorded in laboratory environments, they are still insufficient for practical applications with various types of noise, intonation, and dialects. To cope with this problem, we present a novel unsupervised SVR learning method for practical end-to-end ASR models. Our approach involves designing a speech feature masking method to stabilize SVR model learning and improve the performance of the ASR model in a downstream task. By introducing a noise masking strategy into diverse combinations of the time and frequency regions of the spectrogram, the SVR model becomes a robust representation extractor for the ASR model in practical scenarios. In pretraining experiments, we train the SVR model using approximately 18,000 h of Korean speech datasets that included diverse speakers and were recorded in environments with various amounts of noise. The weights of the pretrained SVR extractor are then frozen, and the extracted speech representations are used for ASR model training in a downstream task. The experimental results show that the ASR model using our proposed SVR extractor significantly outperforms conventional methods.

Auditory Fine-Tuned Suppressor of TMS-Clicks (TMS-Click AFTS): A Novel, Perceptually Driven/Tuned Approach for the Reduction in AEP Artifacts in TMS-EEG Studies

TMS contaminates concurrent EEG recordings with Auditory Evoked Potentials (AEPs), which are caused by the perceived impulsive acoustic noise of the TMS coils. We hereby introduce a novel and perceptually motivated/tuned method for the suppression of auditory evoked EEG artifacts of rTMS under the name of “Auditory Fine-Tuned Suppressor of TMS-Clicks” (TMS-click AFTS). The proposed method is based on the deployment of a psychophysically-matched wide-band noise (WBN) masking stimulus, whose parametric synthesis and presentation are based upon adaptive psychophysical optimization. The masking stimulus is constructed individually for each patient/subject, thus facilitating aspects of precision medicine. A specially designed automation software is used for the realization of an adaptive procedure for optimal parameterization of masking noise level, optimizing both the subject’s comfort and the degree of AEP reduction. The proposed adaptive procedure also takes into account the combined effect of TMS intensity level and can as well account for any possibly available subject’s hearing acuity data. To assess the efficacy of the proposed method in reducing the acoustic effects of TMS, we performed TMS-EEG recordings with a 60 channel TMS-compatible EEG system in a cohort of healthy subjects (n = 10) and patients with epilepsy (n = 10) under four conditions (i.e., resting EEG with and without acoustic mask and sham TMS-EEG with and without acoustic mask at various stimulus intensity levels). The proposed approach shows promising results in terms of efficiency of AEP suppression and subject’s comfort and warrants further investigation in research and clinical settings.

Fast processing models effects of reflections on binaural unmasking

Sound reflections and late reverberation alter energetic and binaural cues of a target source, thereby affecting its detection in noise. Two experiments investigated detection of harmonic complex tones, centered around 500 Hz, in noise, in a virtual room with different modifications of simulated room impulse responses (RIRs). Stimuli were auralized using the Simulated Open Field Environment’s (SOFE’s) loudspeakers in anechoic space. The target was presented from the front (0°) or 60° azimuth, while an anechoic noise masker was simultaneously presented at 0°. In the first experiment, early reflections were progressively added to the RIR and detection thresholds of the reverberant target were measured. For a frontal sound source, detection thresholds decreased while adding early reflections within the first 45 ms, whereas for a lateral sound source, thresholds remained constant. In the second experiment, early reflections were removed while late reflections were kept along with the direct sound. Results for a target at 0° show that even reflections as late as 150 ms reduce detection thresholds compared to only the direct sound. A binaural model with a sluggishness component following the computation of binaural unmasking in short windows predicts measured and literature results better than when large windows are used.

Enhanced Place Specificity of the Parallel Auditory Brainstem Response: A Modeling Study.

While each place on the cochlea is most sensitive to a specific frequency, it will generally respond to a sufficiently high-level stimulus over a wide range of frequencies. This spread of excitation can introduce errors in clinical threshold estimation during a diagnostic auditory brainstem response (ABR) exam. Off-frequency cochlear excitation can be mitigated through the addition of masking noise to the test stimuli, but introducing a masker increases the already long test times of the typical ABR exam. Our lab has recently developed the parallel ABR (pABR) paradigm to speed up test times by utilizing randomized stimulus timing to estimate the thresholds for multiple frequencies simultaneously. There is reason to believe parallel presentation of multiple frequencies provides masking effects and improves place specificity while decreasing test times. Here, we use two computational models of the auditory periphery to characterize the predicted effect of parallel presentation on place specificity in the auditory nerve. We additionally examine the effect of stimulus rate and level. Both models show the pABR is at least as place specific as standard methods, with an improvement in place specificity for parallel presentation (vs. serial) at high levels, especially at high stimulus rates. When simulating hearing impairment in one of the models, place specificity was also improved near threshold. Rather than a tradeoff, this improved place specificity would represent a secondary benefit to the pABR's faster test times.

Security demonstration for the quantum noise-based physical layer using variable keys

With the continued advancement of science and technology, a large amount of important information is carried by optical fibre networks. Therefore, it is imperative to use secure transmission strategies to protect important information. The Y-00 cipher that employs multi-order modulation to prevent eavesdropping on ciphertext is a practical candidate for providing data protection at the physical layer. The Y-00 cipher combines the mathematical encryption of multilevel signalling and quantum noise to provide high security to fibre communications. This paper proposes a quantum noise-based physical layer secure transmission scheme, combining the Y-00 cipher with time-domain spectral phase encoding (TDSPE). The operation methods of the Y-00 cipher in the data encryption and TDSPE in the key distribution are introduced. Then, the system performance is investigated by transmission experiments. The noise-masking phenomenon is demonstrated and quantified. The probability of the eavesdropper guessing cipher text correctly is evaluated. Last, the proposed secure transmission is achieved at 1 Gbps over a 100.2 km optical fibre link, with an intensity level of 1,024 and a noise masking number of 71. The experimental results prove the effective feasibility and high security.

Noise and Vibration in Switched Reluctance Motors: A Review on Structural Materials, Vibration Dampers, Acoustic Impedance, and Noise Masking Methods

Today, the majority of the commercial electrified vehicles use Interior Permanent Magnet Motors (IPMSMs) for propulsion. An IPMSM can deliver high starting torque and high efficiency in the low- and medium-speed operation, which makes it attractive for propulsion applications. However, IPMSMs generally utilize rare-earth permanent magnets and there are growing concerns about the price volatility and supply chain of these materials. Switched Reluctance Motors (SRMs) can potentially replace IPMSMs in various applications including propulsion. An SRM has a simple and low-cost construction, and it can provide reliable operation at high-speed and high-temperature conditions. Compared to IPMSMs, SRMs radiate considerably higher acoustic noise, which have historically hindered their widespread acceptance. Various approaches to mitigate acoustic noise and vibration at the source level have already been explored in the literarture by improving the electromagnetic design and current control. This paper explores multiple noise and vibration mitigation methods that can be applied at the transmission stage. First, the noise comparison between the Internal Combustion Engine (ICE) and SRMs is discussed, and then the methods used for ICEs are presented for their applicability to SRMs.

Effect of Hearing Device Use on Speech-in-Noise Performance in Children with Severe-to-Profound Unilateral Hearing Loss.

Limited evidence exists for the use of rerouting devices in children with severe-to-profound unilateral sensorineural hearing loss. Many laboratory studies to date have evaluated hearing-in-noise performance in specific target-masker spatial configurations within a small group of participants and with only a subset of available hearing devices. In the present study, the efficacy of all major types of nonsurgical devices was evaluated within a larger group of pediatric subjects on a challenging speech-in-noise recognition task. Children (7-18 years) with unaided severe-to-profound unilateral hearing loss (UHL' n = 36) or bilateral normal hearing (NH, n = 36) participated in the present study. The signal-to-noise ratio (SNR) required for 50% speech understanding (SNR-50) was measured using BKB sentences in the presence of proprietary restaurant noise (R-SPACE BSIN-R) in the R-SPACE Sound System. Subjects listened under 2 target/masker spatial configurations. The target signal was directed toward subjects' NH or hearing-impaired ear (45º azimuth), while the interfering restaurant noise masker was presented from the remaining 7 loudspeakers encircling the subject, spaced every 45º. Head position was fixed during testing. The presentation level of target sentences and masking noise varied over time to estimate the SNR-50 (dB). The following devices were tested in all participants with severe-to-profound UHL: air conduction (AC) contralateral routing of signal (CROS), bone conduction (BC) CROS fitted on a headband with and without the use of remote microphone (RM), and an ear-level RM hearing assistance technology (HAT) system. As a group, participants with severe-to-profound UHL performed best when the target signal was directed toward their NH ear. Across listening conditions, there was an average 8.5 dB improvement in SNR-50 by simply orienting the NH ear toward the target signal. When unaided, participants with severe-to-profound UHL performed as well as participants with NH when the target signal was directed toward the NH ear. Performance was negatively affected by AC CROS when the target signal was directed toward the NH ear, whereas no statistically significant change in performance was observed when using BC CROS. When the target signal was directed toward participants' hearing-impaired ear, all tested devices improved SNR-50 compared with the unaided condition, with small improvements (1-2 dB) observed with CROS devices and the largest improvement (9 dB) gained with the personal ear-level RM HAT system. No added benefit nor decrement was observed when RM was added to BC CROS using a 50/50 mixing ratio when the target was directed toward the impaired ear. In a challenging listening environment with diffuse restaurant noise, SNR-50 was most improved in the study sample when using a personal ear-level RM HAT system. Although tested rerouting devices offered measurable improvement in performance (1-2 dB in SNR-50) when the target was directed to the impaired ear, benefit may be offset by a detriment in performance in the opposing condition. Findings continue to support use of RM HAT for children with severe-to-profound UHL in adverse listening environments, when there is one primary talker of interest, to ensure advantageous SNRs.

Reduction in sound discrimination in noise is related to envelope similarity and not to a decrease in envelope tracking abilities.

Humans and animals constantly face challenging acoustic environments, such as various background noises, that impair the detection, discrimination and identification of behaviourally relevant sounds. Here, we disentangled the role of temporal envelope tracking in the reduction in neuronal and behavioural discrimination between communication sounds in situations of acoustic degradations. By collecting neuronal activity from six different levels of the auditory system, from the auditory nerve up to the secondary auditory cortex, in anaesthetized guinea-pigs, we found that tracking of slow changes of the temporal envelope is a general functional property of auditory neurons for encoding communication sounds in quiet conditions and in adverse, challenging conditions. Results from a go/no-go sound discrimination task in mice support the idea that the loss of distinct slow envelope cues in noisy conditions impacted the discrimination performance. Together, these results suggest that envelope tracking is potentially a universal mechanism operating in the central auditory system, which allows the detection of any between-stimulus difference in the slow envelope and thus copes with degraded conditions. KEY POINTS: In quiet conditions, envelope tracking in the low amplitude modulation range (<20 Hz) is correlated with the neuronal discrimination between communication sounds as quantified by mutual information from the cochlear nucleus up to the auditory cortex. At each level of the auditory system, auditory neurons retain their abilities to track the communication sound envelopes in situations of acoustic degradation, such as vocoding and the addition of masking noises up to a signal-to-noise ratio of -10 dB. In noisy conditions, the increase in between-stimulus envelope similarity explains the reduction in both behavioural and neuronal discrimination in the auditory system. Envelope tracking can be viewed as a universal mechanism that allows neural and behavioural discrimination as long as the temporal envelope of communication sounds displays some differences.

Cocktail party training induces increased speech intelligibility and decreased cortical activity in bilateral inferior frontal gyri. A functional near-infrared study.

The human brain networks responsible for selectively listening to a voice amid other talkers remain to be clarified. The present study aimed to investigate relationships between cortical activity and performance in a speech-in-speech task, before (Experiment I) and after training-induced improvements (Experiment II). In Experiment I, 74 participants performed a speech-in-speech task while their cortical activity was measured using a functional near infrared spectroscopy (fNIRS) device. One target talker and one masker talker were simultaneously presented at three different target-to-masker ratios (TMRs): adverse, intermediate and favorable. Behavioral results show that performance may increase monotonically with TMR in some participants and failed to decrease, or even improved, in the adverse-TMR condition for others. On the neural level, an extensive brain network including the frontal (left prefrontal cortex, right dorsolateral prefrontal cortex and bilateral inferior frontal gyri) and temporal (bilateral auditory cortex) regions was more solicited by the intermediate condition than the two others. Additionally, bilateral frontal gyri and left auditory cortex activities were found to be positively correlated with behavioral performance in the adverse-TMR condition. In Experiment II, 27 participants, whose performance was the poorest in the adverse-TMR condition of Experiment I, were trained to improve performance in that condition. Results show significant performance improvements along with decreased activity in bilateral inferior frontal gyri, the right dorsolateral prefrontal cortex, the left inferior parietal cortex and the right auditory cortex in the adverse-TMR condition after training. Arguably, lower neural activity reflects higher efficiency in processing masker inhibition after speech-in-speech training. As speech-in-noise tasks also imply frontal and temporal regions, we suggest that regardless of the type of masking (speech or noise) the complexity of the task will prompt the implication of a similar brain network. Furthermore, the initial significant cognitive recruitment will be reduced following a training leading to an economy of cognitive resources.

Consistency in responses to conspecific advertisement calls with various signal-to-noise ratios in both sexes of the Anhui tree frog.

Environmental noise has a significant negative impact on acoustic communication in most situations, as it influences the production, transmission, and reception of acoustic signals. However, how animals respond to conspecific sounds when there is interference from environmental noise, and whether males and females display convergent behavioral responses in the face of noise masking remain poorly understood. In this study, we investigated the effects of conspecific male advertisement calls with different signal-to-noise ratios on male-male competition and female choice in the Anhui tree frog Rhacophorus zhoukaiyae using playback and phonotaxis experiments, respectively. The results showed that (1) female Anhui tree frogs preferentially selected the conspecific calls with higher SNR compared to calls with lower SNR; (2) males preferentially responded vocally to the conspecific calls with higher SNR compared to calls with lower SNR; and (3) males' competitive strategies were flexible in the face of noise interference. These results suggest that preferences of both sexes converge in outcome, and that male competitive strategies may depend on predictable female preferences. This study will provide an important basis for further research on decision-making in animals.

MOSAICS: A software suite for analysis of membrane structure and dynamics in simulated trajectories

Molecular dynamics (MD) simulations have become the predominant computational analysis method in membrane biophysics, as this technique is uniquely suited for investigations of complex molecular systems through the relevant physical principles. Owing to continued improvements in scope and performance, the trajectories generated through this approach contain ever-increasing amounts of information, which must be synthesized and simplified in post-analysis using tools that are not only mechanistically insightful but also computationally efficient and highly scalable. Here, we introduce MOSAICS, a self-contained high-performance suite of C++ software tools designed for advanced analyses of lipid bilayer structure and dynamics from MD trajectories. MOSAICS is to our knowledge the most comprehensive software suite of this kind, enabling analysis of a wide array of morphological and kinetic properties, for both simple and complex membranes, irrespective of system size or resolution. Importantly, MOSAICS is designed to provide spatial distributions of all computed quantities, with built-in masking tools, noise filtering, and statistical significance metrics to facilitate quantitative interpretations of the trajectory data; it is also fully parallelized and can therefore leverage the capabilities of supercomputing facilities. Despite its technical sophistication, MOSAICS is user-friendly and requires minimal computational expertise, making it accessible to researchers of all skill levels. This sofware suite can be freely downloaded at https://github.com/MOSAICS-NIH/.

Multisensory benefits for speech recognition in noisy environments.

A series of our previous studies explored the use of an abstract visual representation of the amplitude envelope cues from target sentences to benefit speech perception in complex listening environments. The purpose of this study was to expand this auditory-visual speech perception to the tactile domain. Twenty adults participated in speech recognition measurements in four different sensory modalities (AO, auditory-only; AV, auditory-visual; AT, auditory-tactile; AVT, auditory-visual-tactile). The target sentences were fixed at 65 dB sound pressure level and embedded within a simultaneous speech-shaped noise masker of varying degrees of signal-to-noise ratios (-7, -5, -3, -1, and 1 dB SNR). The amplitudes of both abstract visual and vibrotactile stimuli were temporally synchronized with the target speech envelope for comparison. Average results showed that adding temporally-synchronized multimodal cues to the auditory signal did provide significant improvements in word recognition performance across all three multimodal stimulus conditions (AV, AT, and AVT), especially at the lower SNR levels of -7, -5, and -3 dB for both male (8-20% improvement) and female (5-25% improvement) talkers. The greatest improvement in word recognition performance (15-19% improvement for males and 14-25% improvement for females) was observed when both visual and tactile cues were integrated (AVT). Another interesting finding in this study is that temporally synchronized abstract visual and vibrotactile stimuli additively stack in their influence on speech recognition performance. Our findings suggest that a multisensory integration process in speech perception requires salient temporal cues to enhance speech recognition ability in noisy environments.

Analysis-by-synthesis based training target extraction of the DNN for noise masking

In conventional speech enhancement methods, the target of noise mask in the time-frequency domain is based on deep neural networks (DNN), such as ideal ratio mask and phase-sensitive mask, in which they do not consider the dependency of spectrum. In this paper, an ideal real-valued ratio mask (IRVRM) extraction method is proposed based on the analysis-by-synthesis (ABS) for utilizing the dependency of spectrum. In the synthesis process, the enhanced speech is obtained by inverse short-time Fourier transform (ISTFT) of the masked spectrum, whereas in the analysis process, the IRVRM is determined by maximizing speech quality of the reconstructed speech from mask space. The ABS loop algorithm is proposed to reduce computational complexity, namely, the best mask in the specifically generated subspace is conducted in each loop. After the ABS loop, the approximated IRVRM is conducted. This IRVRM is further utilized as the training target of the DNN. The experimental results show that when the extracted IRVRM with the ABS loop is employed as the training target of the DNN, the speech quality is effectively improved in the DNN-based noise masking.

The role of visual cues indicating onset times of target speech syllables in release from informational or energetic masking

• Listeners benefit from visually guided cues for the timing of syllables in noise. • Visual cues are redundant when there are auditory temporal cues from speech rhythm. • Visual cues are more effective at reducing informational than energetic masking. This study examined the effect of visual cues that provide the timing information of syllables in nonsense target sentences on the recognition of target speech against either a speech-spectrum noise masker or a two-talker masker. When the target sentences with normally regular rhythm were used (Experiment 1), visual cues indicating the onset times of the target-sentence syllables did not significantly improve target-speech recognition against either the speech-spectrum noise masker or the two-talker masker. On the other hand, recognition of the last (third) keyword in these normal rhythmic sentences was significantly better than that of the first keyword against the two-talker masker, but not the noise masker. This word-position-related speech-recognition improvement indicates a beneficial role of regular speech rhythm in release from informational masking due to the temporal prediction of target-sentence syllables. When artificially irregular rhythms were introduced into target sentences (Experiment 2), visual cues indicating syllable onset times significantly improved target-speech recognition against both types of masker. Moreover, the visual-cue-induced improvement in speech recognition against the two-talker masker was significantly larger than that against the speech-spectrum noise masker. The results of this study suggested that visual cues indicating target-syllable timing information improve target-speech recognition against competing maskers only when the temporal rhythmic regularity of target speech sentences is reduced.

Familiarity of Background Music Modulates the Cortical Tracking of Target Speech at the "Cocktail Party".

The “cocktail party” problem—how a listener perceives speech in noisy environments—is typically studied using speech (multi-talker babble) or noise maskers. However, realistic cocktail party scenarios often include background music (e.g., coffee shops, concerts). Studies investigating music’s effects on concurrent speech perception have predominantly used highly controlled synthetic music or shaped noise, which do not reflect naturalistic listening environments. Behaviorally, familiar background music and songs with vocals/lyrics inhibit concurrent speech recognition. Here, we investigated the neural bases of these effects. While recording multichannel EEG, participants listened to an audiobook while popular songs (or silence) played in the background at a 0 dB signal-to-noise ratio. Songs were either familiar or unfamiliar to listeners and featured either vocals or isolated instrumentals from the original audio recordings. Comprehension questions probed task engagement. We used temporal response functions (TRFs) to isolate cortical tracking to the target speech envelope and analyzed neural responses around 100 ms (i.e., auditory N1 wave). We found that speech comprehension was, expectedly, impaired during background music compared to silence. Target speech tracking was further hindered by the presence of vocals. When masked by familiar music, response latencies to speech were less susceptible to informational masking, suggesting concurrent neural tracking of speech was easier during music known to the listener. These differential effects of music familiarity were further exacerbated in listeners with less musical ability. Our neuroimaging results and their dependence on listening skills are consistent with early attentional-gain mechanisms where familiar music is easier to tune out (listeners already know the song’s expectancies) and thus can allocate fewer attentional resources to the background music to better monitor concurrent speech material.

Effects of familiarity and likability on music masking of aircraft flyover noise for young people

As typical and unique traffic noise, aircraft flyover noise is difficult to be effectively solved by traditional noise control treatments. For unsteady aircraft noise, music masking is considered to be a feasible method for subjective feeling improvement. This study aims to explore the effect of music likability and familiarity on the masking effect and analyze the relationships for young people. 15 music clips from six genres were firstly screened as masking sounds in terms of familiarity and likability difference. Two kinds of subjective scoring methods were adopted for total 60 participants to evaluate the annoyance reduction level. The correlation was analyzed and the masking effect prediction model was obtained from likability and familiarity. The results showed that the likability and familiarity had significant effects of masking effect. According to the annoyance reduction percentage, the masking effect had a significant positive correlation to likability. As for familiarity, there was a critical value for the best masking effect.

Spatial release from masking in crocodilians

Ambient noise is a major constraint on acoustic communication in both animals and humans. One mechanism to overcome this problem is Spatial Release from Masking (SRM), the ability to distinguish a target sound signal from masking noise when both sources are spatially separated. SRM is well described in humans but has been poorly explored in animals. Although laboratory tests with trained individuals have suggested that SRM may be a widespread ability in vertebrates, it may play a limited role in natural environments. Here we combine field experiments with investigations in captivity to test whether crocodilians experience SRM. We show that 2 species of crocodilians are able to use SRM in their natural habitat and that it quickly becomes effective for small angles between the target signal source and the noise source, becoming maximal when the angle exceeds 15∘. Crocodiles can therefore take advantage of SRM to improve sound scene analysis and the detection of biologically relevant signals.