A 1/3 Octave-Band Noise Generator for Sound-Field Audiometric Measurements

1982 ◽  
Vol 47 (1) ◽  
pp. 84-88
Author(s):  
Richard Lippmann ◽  
Doug Adams
Keyword(s):  
Frequency Response ◽  
Low Cost ◽  
Sound Field ◽  
Field Measurements ◽  
Noise Generator ◽  
Center Frequency ◽  
Octave Band ◽  
Band Noise ◽  
Switch Capacitor ◽  
Band Filter

The design of a low-cost 1/3 octave-band noise generator is presented. This device produces 1/3 octave bands of noise with center frequencies from 100 to 10,000 Hz using a recently introduced switch-capacitor filter with a frequency response which is similar to that of the 1/2 octave filters in the GR 1925 multifilter. The spectrum level of the noise bands produce by this device falls at a rate of 60 dB/octave or more. The noise generator may be used with an audiometer for sound-field measurements in non-anechoic audiometric testing rooms or for earphone measurements. It may also be used as a 1/3 octave-band filter with a center frequency from 100 to 10,000 Hz or as an octave-band filter with a center frequency from 125 to 8000 Hz.

Decay of Temporary Threshold Shift in Noise

1973 ◽  
Vol 16 (2) ◽  
pp. 267-270 ◽  
Author(s):  
John H. Mills ◽  
Seija A. Talo ◽  
Gloria S. Gordon
Keyword(s):  
Sound Field ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Octave Band ◽  
Band Noise ◽  
Lower Asymptote

Groups of monaural chinchillas trained in behavioral audiometry were exposed in a diffuse sound field to an octave-band noise centered at 4.0 k Hz. The growth of temporary threshold shift (TTS) at 5.7 k Hz from zero to an asymptote (TTS ∞ ) required about 24 hours, and the growth of TTS at 5.7 k Hz from an asymptote to a higher asymptote, about 12–24 hours. TTS ∞ can be described by the equation TTS ∞ = 1.6(SPL-A) where A = 47. These results are consistent with those previously reported in this journal by Carder and Miller and Mills and Talo. Whereas the decay of TTS ∞ to zero required about three days, the decay of TTS ∞ to a lower TTS ∞ required about three to seven days. The decay of TTS ∞ in noise, therefore, appears to require slightly more time than the decay of TTS ∞ in the quiet. However, for a given level of noise, the magnitude of TTS ∞ is the same regardless of whether the TTS asymptote is approached from zero, from a lower asymptote, or from a higher asymptote.

High-Frequency Hearing Losses Caused by Low-Frequency Noises

1978 ◽  
Vol 86 (5) ◽  
pp. ORL-821-ORL-823 ◽  
Author(s):  
John H. Mills ◽  
Warren Y. Adkins ◽  
Robert M. Gilbert
Keyword(s):  
High Frequency ◽  
Human Subjects ◽  
Low Frequency ◽  
Wave Pattern ◽  
Travelling Wave ◽  
Center Frequency ◽  
Octave Band ◽  
Distortion Products ◽  
Band Noise ◽  
Cochlear Partition

Human subjects were exposed to an octave-band noise for 24 hours. Temporary threshold shifts increased for the first eight hours of exposure and then were asymptotic. While threshold shifts were largest at about one-half octave above the center frequency of the noise, a second maximum was observed at higher test frequencies. The exact frequency of this second maximum decreased from 7.0 kHz, for a noise centered at 2.0 kHz, to 5.5 kHz for a noise centered at 0.5 kHz. This result could be caused by the travelling wave pattern along the cochlear partition or to the production of distortion products.

Normalized Error Estimates for One-Third Octave Band Filter Processing

2004 ◽  
Vol 47 (1) ◽  
pp. 87-93
Author(s):  
Ronald Merritt
Keyword(s):  
Time History ◽  
Center Frequency ◽  
External Information ◽  
Octave Band ◽  
Processing Error ◽  
Normalized Error ◽  
Band Filter ◽  
Substantial Bias ◽  
The One ◽  
Half Power

This paper summarizes numerically derived theoretical estimates of normalized random and normalized bias errors for one-third octave band filters applied to autoregressive processes of order two. It demonstrates that one-third octave band estimates of such processes may have substantial bias errors depending upon (1) frequency location of a true spectra peak relative to the center frequency of the one-third octave band filter and (2) half-power bandwidth of the true spectra. One-third octave band processing error is contrasted with narrowband processing error. It concludes that one-third octave band processing should be avoided whenever external information would indicate that the underlying time history data may have a narrowband character.

Temporary Threshold Shifts Produced by Exposure to High-Frequency Noise

1972 ◽  
Vol 15 (3) ◽  
pp. 624-631 ◽  
Author(s):  
John H. Mills ◽  
Seija A. Talo
Keyword(s):  
High Frequency ◽  
Noise Exposure ◽  
Sound Field ◽  
Acoustic Properties ◽  
Threshold Shift ◽  
Maximum Effect ◽  
Frequency Noise ◽  
Temporary Threshold Shift ◽  
Octave Band ◽  
Band Noise

Four chinchillas, monaural and trained in behavioral audiometry, were exposed for 24 days in a diffuse-sound field to an octave-band noise centered at 4.0 k Hz. The octave-band levels (OBL re 0.0002 ubar) were 57 dB for Days 1 to 6; 65 dB for Days 7 to 12; 72 dB for Days 13 to 18; and 80 dB for Days 19 to 24. At regular intervals throughout the noise exposure each animal was removed from the noise and threshold measurements were made. For each level of noise, temporary threshold shift reached an asymptote. In the frequency region of maximum effect, the relation between temporary threshold shift and the level of the noise is given by the equation TTS 4 ∞ = 1.6 (OBL-47) where TTS 4 ∞ is the temporary threshold shift at asymptote measured at a postexposure time of four minutes. These results for a noise centered at 4.0 k Hz in combination with those results for a noise centered at 0.5 k Hz suggest that bands of noise produce equal TTS 4 ∞ when the levels of the noises are equated for the acoustic properties of the external ear (including the head) and the inner ear.

Bilayer split-ring chiral metamaterial based reconfigurable antenna for polarization conversion

Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Preet Kaur ◽  
Pravin R. Prajapati
Keyword(s):  
Low Cost ◽  
Axial Ratio ◽  
Center Frequency ◽  
Impedance Bandwidth ◽  
Split Ring ◽  
Circularly Polarized ◽  
Left Hand ◽  
Rectangular Patch ◽  
Mode 2 ◽  
Chiral Metamaterial

Abstract A bilayer split-ring chiral metamaterial converts the linearly polarized wave, into a nearly perfect left or right-handed circularly polarized wave. The proposed antenna is intended to operate at center frequency of 5.80 GHz with switchable polarization capability. The polarization re-configurability is achieved by electronically switching of two PIN-diode pairs, which are embedded into bilayer split-ring Chiral Metamaterial. The optimized length of rectangular patch is 16 mm and width is 12.1 mm. Two types of radiation characteristics offered by the proposed antenna; left hand circularly polarized in mode 1 and right hand circularly polarized in mode 2. Measured results show that its impedance bandwidth is 155 MHz from 5.70 to 5.855 GHz for both mode 1 and mode 2. The measured axial-ratio bandwidth is 100 MHz from 5.75 to 5.85 GHz for mode 1 and 110 MHz from 5.73 to 5.84 GHz for mode 2. Antenna has LHCP gain of 2.52 dBi and RHCP gain of −23 dBi in mode 1. RHCP gain of 2 dBi and polarization purity of about −20 dBi is obtained in mode 2. The proposed antenna has simple structure, low cost and it has potential application in field of wireless communication (i.e., WiMax, WLAN etc.).

Design of an Ideal Low Pass Microstrip Line Filter Using the Defected Ground Structure

2018 ◽  
Vol 876 ◽  
pp. 133-137
Author(s):  
Ping Cheng Chen ◽  
Chung Long Pan ◽  
J.D. Huang ◽  
S.H. Hong
Keyword(s):  
Frequency Response ◽  
Microstrip Line ◽  
Geometric Shape ◽  
Center Frequency ◽  
Defected Ground Structure ◽  
Ground Structure ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Ansoft Hfss ◽  
Low Pass

A design and simulation for low pass microstrip line filter with defected ground structure has been researched, the main purpose is with the simplest method to design an ideal low pass filter. In this paper, simulated soft (Ansoft HFSS V.6.0) used to be simulated the frequency response under different geometric shape of DGS. The results show good performance of a low pass filter with DGS. Final, a low pass filter with DGS design and fabricated, The properties are shown as flow: center-frequency: 7.28G, S21:-47dB, cut-off frequency: 5.88GHz.

Effect of ceiling and dry-type double floor on heavy-weight floor impact sound in concrete building and CLT building.

2021 ◽  
Vol 263 (3) ◽  
pp. 3064-3072
Author(s):  
Takashi Yamauchi ◽  
Atsuo Hiramitsu ◽  
Susumu Hirakawa
Keyword(s):  
Frequency Band ◽  
Sound Level ◽  
Center Frequency ◽  
Sound Insulation ◽  
Octave Band ◽  
Band Center ◽  
Heavy Weight ◽  
Concrete Building ◽  
Floor Structure ◽  
Insulation Performance

The air layer between the interior finishes and the structure is used as piping and wiring space. In many cases, ceilings and dry-type double floors are commonly constructed in Japan. However, the effect of the air layer of ceilings and dry-type double floors on the heavy-weight floor impact sound insulation performance has not yet quantitatively investigated. Therefore, in this study, the same floor and ceiling structures were constructed for concrete and CLT buildings, and the heavy-weight floor impact sound was investigated. As results, it was confirmed that the reduction amount of the heavy-weight floor impact sound by the ceiling tended to be smaller in CLT buildings than in concrete buildings. However, the trends were similar. Due to the dry-type double floor structure, the heavy-weight floor impact sound level was increased in concrete building and decreased in CLT building at 63 Hz in the octave band center frequency band. Therefore, it can be said that the dry-type double floor structure can be used to improve the heavy-weight floor impact sound performance in the CLT building.

Correspondence between Site Amplification and Topographical, Geological Parameters: Collation of Data from Swiss and Japanese Stations, and Neural Networks-Based Prediction of Local Response

2021 ◽  
Author(s):  
Paolo Bergamo ◽  
Conny Hammer ◽  
Donat Fäh
Keyword(s):  
Frequency Response ◽  
Large Scale ◽  
Site Response ◽  
Low Frequency ◽  
Field Measurements ◽  
Site Amplification ◽  
Local Response ◽  
Regional Variability ◽  
Individual Site ◽  
Digital Elevation

ABSTRACT We address the relation between seismic local amplification and topographical and geological indicators describing the site morphology. We focus on parameters that can be derived from layers of diffuse information (e.g., digital elevation models, geological maps) and do not require in situ surveys; we term these parameters as “indirect” proxies, as opposed to “direct” indicators (e.g., f0, VS30) derived from field measurements. We first compiled an extensive database of indirect parameters covering 142 and 637 instrumented sites in Switzerland and Japan, respectively; we collected topographical indicators at various spatial extents and focused on shared features in the geological descriptions of the two countries. We paired this proxy database with a companion dataset of site amplification factors at 10 frequencies within 0.5–20 Hz, empirically measured at the same Swiss and Japanese stations. We then assessed the robustness of the correlation between individual site-condition indicators and local response by means of statistical analyses; we also compared the proxy-site amplification relations at Swiss versus Japanese sites. Finally, we tested the prediction of site amplification by feeding ensembles of indirect parameters to a neural network (NN) structure. The main results are: (1) indirect indicators show higher correlation with site amplification in the low-frequency range (0.5–3.33 Hz); (2) topographical parameters primarily relate to local response not because of topographical amplification effects but because topographical features correspond to the properties of the subsurface, hence to stratigraphic amplification; (3) large-scale topographical indicators relate to low-frequency response, smaller-scale to higher-frequency response; (4) site amplification versus indirect proxy relations show a more marked regional variability when compared with direct indicators; and (5) the NN-based prediction of site response is the best achieved in the 1.67–5 Hz band, with both geological and topographical proxies provided as input; topographical indicators alone perform better than geological parameters.

An Innovative Low Cost Well Monitoring Solution: W.A.N.D

2021 ◽  
Author(s):  
Jean Grégoire Boero Rollo ◽  
John Richard Ordonez Varela ◽  
Tayssir Ben Ghzaiel ◽  
Cedric Mouanga ◽  
Arnaud Luxey ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Low Power ◽  
Low Cost ◽  
Field Measurements ◽  
Cost Effective ◽  
Complex Environment ◽  
Sensor Device ◽  
Magnetic Field Measurements ◽  
Pipeline Monitoring ◽  
Harsh Conditions

Abstract Wireless Autonomous Nano-sensor Device (WAND) system is a disruptive cost-effective micro-system for well monitoring. It allows to realize pressure, temperature, inertial, and magnetic field measurements in harsh conditions; it also offers Bluetooth low-power communication and Wireless charging capabilities. Analysis’ results of an industrial offshore pilot realized in Congo (a world first in O&G industry in such complex environment), and major improvements implemented after this pilot are reported in this paper. Accomplished advancements comprise hardware and software developments extending operation lifetime, and simplifying on-site utilization. To date, there is not a commercial solution of this type in the market, the realization of this project is a real innovation allowing practical and low-cost monitoring during well intervention while minimizing the risks associated with standard Rigless intervention. Other applications regarding dry-tree wells on tension-leg platforms (TLP), drilling and completion operations, and pipeline monitoring are being investigated, too.

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