scholarly journals Prediction of masked detection thresholds for noise signals centered in a gated noise masker

1993 ◽  
Vol 94 (3) ◽  
pp. 1776-1776
Author(s):  
C. Formby ◽  
M. G. Heinz ◽  
C. E. Luna
Keyword(s):  
Detection Thresholds ◽  
Noise Masker ◽  
Gated Noise ◽  
Masked Detection

Masked and unmasked pure tone detection thresholds of a harbour seal listening in air

1991 ◽  
Vol 69 (8) ◽  
pp. 2059-2066 ◽  
Author(s):  
J. M. Terhune
Keyword(s):  
White Noise ◽  
Pure Tone ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Optimal Conditions ◽  
Vascular Changes ◽  
Detection Thresholds ◽  
Noise Masker ◽  
Auditory Systems ◽  
Tone Detection

In-air pure tone detection thresholds of a harbour seal (Phoca vitulina) were measured using behavioural psychophysical techniques. Thresholds dropped from about 70 dB re 20 μPa at 0.1 kHz to about 35 dB re 20 μ Pa at 4 kHz and then increased to about 45 dB re 20 μPa at 16 kHz. Increased sensitivities at 2 and 8 kHz, which have been reported in other pinnipeds, were not evident. In-air intensity detection thresholds averaged 32 dB above their underwater counterparts (1–16 kHz). Masking studies found the critical ratios at 0.25, 0.5, and 1 kHz to be 24, 15, and 21 dB, respectively (white noise masker). From 0.2 to 1.5 kHz, bandwidths 20 dB below the level of pure tone maskers were 0.16–0.18 kHz. Circumstantial evidence suggests the possibility that blood vascular changes associated with diving might also influence the sensitivity of the auditory systems of seals. Under optimal conditions, a pup's airborne cries may be detected by its mother at ranges of 1 km or more.

Changes in masked thresholds of a harbour seal (Phoca vitulina) associated with angular separation of signal and noise sources

1994 ◽  
Vol 72 (11) ◽  
pp. 1863-1866 ◽  
Author(s):  
S. D. Turnbull
Keyword(s):  
White Noise ◽  
Pure Tone ◽  
Noise Source ◽  
Angular Separation ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Noise Sources ◽  
Detection Thresholds ◽  
Noise Masker ◽  
Significant Difference

The masked pure tone thresholds of a harbour seal (Phoca vitulina) were measured at various angles using a white noise masker. The white noise source was placed at 0°, 30°, 60°, and 90° relative to the midline of the seal's head (0°). The masked pure tone thresholds for each angle were determined at 2, 4, 8, and 16 kHz. As the angle separating the signal and noise sources increased from 0° to 90°, the critical ratios of the harbour seal decreased by 1–4 dB. This shift in masked thresholds from a reference point of 0° azimuth was significant (H = 10.374, df = 3,16, p < 0.05). No significant difference was found in masked thresholds between 0° and 30° or between 60° and 90°. This indicates that if a noise source is separated by more than 30° relative to the location of a vocalizing seal, signal detection thresholds will be enhanced and communication distances increased.

scholarly journals An electrophysiological measure of tonotopic selectivity in normal-hearing humans and cats

2021 ◽  
Author(s):  
François Guérit ◽  
John C. Middlebrooks ◽  
Matthew L. Richardson ◽  
Andrew Harland ◽  
Robin Gransier ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Tone Burst ◽  
Companion Paper ◽  
Non Invasive ◽  
Noise Masker ◽  
Probe Frequency ◽  
Continuous Noise ◽  
Masked Detection ◽  
Excitation Pattern ◽  
Onset Response

We describe a non-invasive electrophysiological (EEG) measure of tonotopic selectivity and compare the results between humans and cats. Sequences of 50-ms tone-burst probes were presented at 1-second intervals against a continuous noise masker, and the averaged cortical onset response (COR) to the probe was measured using EEG electrodes placed on the scalp. The noise masker had a bandwidth of 1 or 1/8th octave, geometrically centred on 4000 Hz for humans and 8000 Hz for cats. Probe frequency was either -0.5, -0.25, 0, 0.25 or 0.5 octaves re 4000/8000 Hz. The COR was larger for probe frequencies more distant from the noise geometrical centre, and this effect was greater for the 1/8th-octave than for the 1-octave masker. This pattern broadly reflected the masked excitation patterns obtained psychophysically with similar stimuli in a companion paper. However, the positive signal-to-noise ratio used to obtain reliable COR measures meant that some aspects of the data differed from those obtained psychophysically, in a way that could be partly explained by the upward spread of the probe’s excitation pattern. We argue that although COR measures are affected by some factors that differ from those that influence psychophysical masked detection thresholds, they can reveal differences in the width of excitation patterns produced by different stimuli. We also argue that the paradigm may be effectively applied to cochlear-implant experiments in humans and animals.

Masked detection thresholds and temporal integration for noise band signals

1994 ◽  
Vol 96 (1) ◽  
pp. 102-114 ◽  
Author(s):  
C. Formby ◽  
M. G. Heinz ◽  
C. E. Luna ◽  
M. K. Shaheen
Keyword(s):  
Temporal Integration ◽  
Noise Band ◽  
Detection Thresholds ◽  
Masked Detection

Analysis and Identification of Off-Odor Compounds in Electronic Systems

2006 ◽  
Author(s):  
Mary Ann Nailos ◽  
Dan Stein ◽  
Lawrence T. Nielsen ◽  
Anna Iwasinska
Keyword(s):  
Volatile Compounds ◽  
Electronic Systems ◽  
Detection Thresholds ◽  
Detection And Identification ◽  
Odor Compounds ◽  
Novel Method ◽  
Odor Analysis ◽  
Analytical System ◽  
Task Perception ◽  
Analytical Tools

Abstract The detection and identification of substances that give rise to aromas and off-odors is often a difficult task. Perception of odors is very subjective and odor detection thresholds vary from person to person. The identification of trace levels of compounds responsible for perceived odors is difficult using conventional analytical tools. This paper will focus on a novel method for sampling and analyzing aromatic volatile compounds using an analytical system specifically designed for odor analysis.

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