Interaction of seismic background noise with oscillating pore fluids causes spectral modifications of passive seismic measurements at low frequencies

2007 ◽  
Author(s):  
Marcel Frehner ◽  
Stefan M. Schmalholz ◽  
Yuri Podladchikov
Keyword(s):  
Background Noise ◽  
Pore Fluids ◽  
Low Frequencies ◽  
Passive Seismic ◽  
Seismic Background ◽  
Seismic Measurements

scholarly journals Characterization of a complex near-surface structure using well logging and passive seismic measurements

2016 ◽  
Author(s):  
Beatriz Benjumea ◽  
Albert Macau ◽  
Anna Gabàs ◽  
Sara Figueras
Keyword(s):  
Wave Velocity ◽  
Upper Cretaceous ◽  
Seismic Velocity ◽  
Well Logging ◽  
P Wave ◽  
Geophysical Field ◽  
Near Surface ◽  
Passive Seismic ◽  
Surface Geology ◽  
Seismic Measurements

Abstract. We combine geophysical well logging and passive seismic measurements to characterize the near surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near surface geology includes an upper layer of pure limestones overlying marly limestones and marls (Upper Cretaceous). These materials lie on top of Low Cretaceous siliciclastic sediments (sandstones, clays, gravels). In any case, decreasing seismic velocity with depth is expected. The geophysical datasets used in this study include sonic and gamma ray logs at two boreholes and passive seismic measurements: 224 H/V stations and 3 arrays. Well logging data defines two significant changes in the P-wave velocity log within the Upper Cretaceous layer and one more at the Upper to Lower Cretaceous contact. This technique has also used for refining the geological interpretation. The passive seismic measurements provide a map of sediment thickness with maximum of around 40 m and shear-wave velocity profiles from the array technique. A comparison between seismic velocity coming from well logging and array measurements defines the resolution limits of the passive seismic techniques and helps for its interpretation. This study shows how these low-cost techniques can provide useful information about near-surface complexity that could be used for designing a geophysical field survey or for seismic processing steps such as statics or imaging.

Retrieval of reflections from seismic background-noise measurements

2007 ◽  
Vol 34 (4) ◽  
Author(s):  
Deyan Draganov ◽  
Kees Wapenaar ◽  
Wim Mulder ◽  
Johannes Singer ◽  
Arie Verdel
Keyword(s):  
Background Noise ◽  
Noise Measurements ◽  
Seismic Background

scholarly journals Speech-to-touch sensory substitution: a 10-decibel improvement in speech-in-noise understanding after a short training

2021 ◽  
Author(s):  
Katarzyna Ciesla ◽  
T. Wolak ◽  
A. Lorens ◽  
H. Skarżyński ◽  
A. Amedi
Keyword(s):  
Speech Processing ◽  
Background Noise ◽  
Sensory Modality ◽  
Training Session ◽  
Real Life ◽  
Sensory Substitution ◽  
Low Frequencies ◽  
Speech In Noise ◽  
Lower Magnitude ◽  
Neuronal Computation

Abstract Understanding speech in background noise is challenging. Wearing face-masks during COVID19-pandemics made it even harder. We developed a multi-sensory setup, including a sensory substitution device (SSD) that can deliver speech simultaneously through audition and as vibrations on fingertips. After a short training session, participants significantly improved (16 out of 17) in speech-in-noise understanding, when added vibrations corresponded to low-frequencies extracted from the sentence. The level of understanding was maintained after training, when the loudness of the background noise doubled (mean group improvement of ~ 10 decibels). This result indicates that our solution can be very useful for the hearing-impaired patients. Even more interestingly, the improvement was transferred to a post-training situation when the touch input was removed, showing that we can apply the setup for auditory rehabilitation in cochlear implant-users. Future wearable implementations of our SSD can also be used in real-life situations, when talking on the phone or learning a foreign language. We discuss the basic science implications of our findings, such as we show that even in adulthood a new pairing can be established between a neuronal computation (speech processing) and an atypical sensory modality (tactile). Speech is indeed a multisensory signal, but learned from birth in an audio-visual context. Interestingly, adding lip reading cues to speech in noise provides benefit of the same or lower magnitude as we report here for adding touch.

Aircraft interior acoustics - background noise contamination

2021 ◽  
Vol 263 (5) ◽  
pp. 1606-1619
Author(s):  
Ramana Kappagantu ◽  
Manuel Etchessahar ◽  
Edgar Matas ◽  
Koen Vansant
Keyword(s):  
High Frequency ◽  
Background Noise ◽  
Noise Source ◽  
Operating Conditions ◽  
Low Frequencies ◽  
Acoustic Design ◽  
Points Of Interest ◽  
Transmission Index ◽  
Speech Transmission ◽  
Noise Contamination

Aircraft interior noise is an important factor to be considered for cabin comfort. In a cruising condition this noise source is mostly broadband in nature and is coming from the exterior, primarily the turbulent boundary layer (TBL) of the flow around the moving aircraft. Capturing this noise to a high frequency is critical for designing the sound packaging. Also, this becomes important in the design of public announcement (PA) system for the aircraft cabin, i.e. the correct placement of speakers. One of the metrics used for this acoustic design is speech transmission index. Deterministic techniques like finite or boundary element techniques for low frequencies and ray tracing method to reach higher frequencies are better suited for getting the narrow band responses. On the other hand, to characterize the background noise due to the TBL loads, statistical energy analysis (SEA) route is pursued. In this paper the authors combine different techniques to capture the background noise and use them with PA sources and eventually capture the sound perceived at points of interest. The articulation metrics are compared for different operating conditions of the aircraft. In the presentation attempts will be made to play the auralized sounds.

High-frequency analysis of seismic background noise as a function of wind speed and shallow depth

1996 ◽  
Vol 86 (5) ◽  
pp. 1507-1515 ◽  
Author(s):  
Mitchell M. Withers ◽  
Richard C. Aster ◽  
Christopher J. Young ◽  
Eric P. Chael
Keyword(s):  
Wind Speed ◽  
High Frequency ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Shallow Depth ◽  
High Frequency Signal ◽  
Wind Speeds ◽  
Noise Characteristics ◽  
Cultural Noise ◽  
Seismic Background

Abstract We used a deep (1500 m) cased borehole near the town of Datil in west-central New Mexico to study high-frequency (>1 Hz) seismic noise characteristics. The remote site had very low levels of cultural noise, but strong winds (winter and spring) made the site an excellent candidate to study the effects of wind noise on seismograms. Along with a three-component set of surface sensors (Teledyne Geotech GS-13), a vertical borehole seismometer (GS-28) was deployed at a variety of depths (5, 43, and 85 m) to investigate signal and noise variations. Wind speed was measured with an anemometer. Event-triggered and time-triggered data streams were recorded on a RefTek 72-02 data acquisition system located at the site. Our data show little cultural noise and a strong correlation between wind speed and seismic background noise. The minimum wind speed at which the seismic background noise appears to be influenced varies with depth: 3 m/sec at the surface, 3.5 m/sec at 43 m in depth, and 4 m/sec at 85 m in depth. For wind speed below 3 to 4 m/sec, we observe omni-directional background noise that is coherent at frequencies below 15 Hz. This coherence is destroyed when wind speeds exceed 3 to 4 m/sec. We use a test event (Md ∼ 1.6) and superimposed noise to investigate signal-to-noise ratio (SNR) improvement with sensor depth. For the low Q valley fill of the Datil borehole (DBH) site, we have found that SNR can be improved by as much as 20 to 40 dB between 23 and 55 Hz and 10 to 20 dB between 10 and 20 Hz, by deploying at a 43-m depth rather than at the surface. At the surface, there is little signal above noise in the 23- to 55-Hz frequency band for wind speeds greater than 8 m/sec. Thus, high-frequency signal information that is lost at the surface can be recorded by deploying at the relatively shallow depth of 40 m. Because we observe only minor further reductions in seismic background noise (SBN) at deeper depths, 40 m is likely to be a reasonable deployment depth for other high-frequency-monitoring sites in similar environmental and geologic conditions.

scholarly journals Accelerometer Sensor Specifications to Predict Hydrocarbon Using Passive Seismic Technique

2016 ◽  
Vol 2016 ◽  
pp. 1-28 ◽  
Author(s):  
M. H. Md Khir ◽  
Atul Kumar ◽  
Wan Ismail Wan Yusoff
Keyword(s):  
Oil And Gas ◽  
Optimal Solution ◽  
Seismic Energy ◽  
Oil And Gas Industry ◽  
Seismic Signal ◽  
Accelerometer Sensor ◽  
Low Frequencies ◽  
Technological Gap ◽  
Passive Seismic ◽  
Seismic Acquisition

The ambient seismic ground noise has been investigated in several surveys worldwide in the last 10 years to verify the correlation between observed seismic energy anomalies at the surface and the presence of hydrocarbon reserves beneath. This is due to the premise that anomalies provide information about the geology and potential presence of hydrocarbon. However a technology gap manifested in nonoptimal detection of seismic signals of interest is observed. This is due to the fact that available sensors are not designed on the basis of passive seismic signal attributes and mainly in terms of amplitude and bandwidth. This is because of that fact that passive seismic acquisition requires greater instrumentation sensitivity, noise immunity, and bandwidth, with active seismic acquisition, where vibratory or impulsive sources were utilized to receive reflections through geophones. Therefore, in the case of passive seismic acquisition, it is necessary to select the best monitoring equipment for its success or failure. Hence, concerning sensors performance, this paper highlights the technological gap and motivates developing dedicated sensors for optimal solution at lower frequencies. Thus, the improved passive seismic recording helps in oil and gas industry to perform better fracture mapping and identify more appropriate stratigraphy at low frequencies.

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