High-Level Psychophysical Tuning Curves

1991 ◽  
Vol 34 (2) ◽  
pp. 374-378 ◽  
Author(s):  
David A. Nelson ◽  
Todd W. Fortune
Keyword(s):  
Background Noise ◽  
Narrow Band ◽  
Tuning Curve ◽  
Broad Band ◽  
Low Frequency ◽  
Tuning Curves ◽  
Combination Band ◽  
Critical Bandwidth ◽  
High Level ◽  
Combination Bands

Simultaneous-masked psychophysical tuning curves were measured with narrow-band noise maskers varying in bandwidth from 40 Hz to 800 Hz to determine the masker bandwidths at which combination-band detection cues no longer influence tuning-curve shapes. Tuning curves were obtained at 1000 and 4000 Hz from normal-hearing listeners using high-level (60 dB SPL) probe tones in quiet and in the presence of a broadband background noise to eliminate combination bands and other off-frequency listening cues that exist at high levels. High-level tuning curves revealed notches on the low-frequency sides. Those notches were eliminated with broad-band background noise, which indicates that combination bands can strongly influence the shapes of high-level tuning curves obtained with narrow-band maskers, primarily by steepening the low-frequency and tail slopes. Combination-band detection cues had a stronger influence at 4000 Hz than at 1000 Hz. As masker bandwidth increased, combination bands had less influence on tuning-curve shapes. These results suggest a possible relation between masker bandwidth and auditory critical bandwidth: combination bands affected the lowfrequency sides of the tuning curves only when the masker bandwidth was less than the auditory critical bandwidth.

High-Level Psychophysical Tuning Curves

1991 ◽  
Vol 34 (2) ◽  
pp. 360-373 ◽  
Author(s):  
David A. Nelson ◽  
Todd W. Fortune
Keyword(s):  
Background Noise ◽  
Pure Tone ◽  
Narrow Band ◽  
Tuning Curve ◽  
Broad Band ◽  
Low Frequency ◽  
Tuning Curves ◽  
Tuning Characteristic ◽  
High Level ◽  
Combination Bands

Simultaneous-masked psychophysical tuning curves were obtained from normal-hearing listeners using low-level (20–25 dB SPL) probe tones in quiet and high-level (60 dB SPL) probe tones, both in quiet and in the presence of a broad-band background noise. The background noise was introduced to eliminate combination tones or combination bands and other off-frequency listening cues that exist at high levels. Tuning curves were obtained using pure-tone maskers and 100-Hz-wide narrow-band noise maskers for probe tones at 1000 and 4000 Hz. High-level tuning curves for pure-tone maskers demonstrated large discontinuities or “notches” on the low-frequency sides of the tuning curves. Broad-band background noise eliminated those notches, indicating that the notches were due to the detection of off-frequency listening cues at combination-tone frequencies. High-level tuning curves for 100-Hz-wide narrow-band maskers also demonstrated notches on the low-frequency sides. Those notches were eliminated with broad-band background noise, which indicates that combination bands strongly influenced the shapes of high-level tuning curves obtained with narrow-band maskers. The influence of combination bands was dependent upon test frequency. At 1000 Hz, combination bands had very little influence on the shapes of high-level tuning curves. At 4000 Hz, where the masker bandwidth was substantially less than the critical bandwidth, combination bands strongly affected the low-frequency sides of the tuning curves. In 2 subjects tested at a probe frequency of 2000 Hz with 100-Hz-wide masking bands, combination bands also influenced the lowfrequency sides of high-level tuning curves. The presence of combination-tone or combination-band cues essentially steepened the low-frequency slopes of tuning curves, resulting in sharper estimates of tuning. Comparisons of tuning curves obtained with pure-tone maskers and narrow-band maskers, in the same listeners, revealed that pure-tone maskers were more effective than narrow-band maskers when the masker frequencies were in the tail region of the tuning curve. The results of these experiments support the notion that tuning in the normal auditory system broadens notably with stimulus level, once off-frequency listening cues such as combination tones or combination bands are eliminated. The low-level simultaneously masked tuning curve demonstrates a sharp bandpass tuning characteristic, whereas the high-level simultaneously masked tuning curve in background noise demonstrates a broad low-pass tuning characteristic. It is argued that comparisons of tuning in impaired ears with tuning in normal ears should be made using estimates of tuning in normal ears that are not influenced by combination-tone or combination-band detection cues.

scholarly journals Cochlear compound action potentials from high-level tone bursts originate from wide cochlear regions that are offset toward the most sensitive cochlear region

2019 ◽  
Vol 121 (3) ◽  
pp. 1018-1033 ◽  
Author(s):  
C. Lee ◽  
J. J. Guinan ◽  
M. A. Rutherford ◽  
W. A. Kaf ◽  
K. M. Kennedy ◽  
...  
Keyword(s):  
High Frequency ◽  
Action Potentials ◽  
Tuning Curve ◽  
Low Frequency ◽  
Sound Level ◽  
Frequency Tone ◽  
Compound Action Potentials ◽  
High Level ◽  
Level Tone ◽  
Compound Action

Little is known about the spatial origins of auditory nerve (AN) compound action potentials (CAPs) evoked by moderate to intense sounds. We studied the spatial origins of AN CAPs evoked by 2- to 16-kHz tone bursts at several sound levels by slowly injecting kainic acid solution into the cochlear apex of anesthetized guinea pigs. As the solution flowed from apex to base, it sequentially reduced CAP responses from low- to high-frequency cochlear regions. The times at which CAPs were reduced, combined with the cochlear location traversed by the solution at that time, showed the cochlear origin of the removed CAP component. For low-level tone bursts, the CAP origin along the cochlea was centered at the characteristic frequency (CF). As sound level increased, the CAP center shifted basally for low-frequency tone bursts but apically for high-frequency tone bursts. The apical shift was surprising because it is opposite the shift expected from AN tuning curve and basilar membrane motion asymmetries. For almost all high-level tone bursts, CAP spatial origins extended over 2 octaves along the cochlea. Surprisingly, CAPs evoked by high-level low-frequency (including 2 kHz) tone bursts showed little CAP contribution from CF regions ≤ 2 kHz. Our results can be mostly explained by spectral splatter from the tone-burst rise times, excitation in AN tuning-curve “tails,” and asynchronous AN responses to high-level energy ≤ 2 kHz. This is the first time CAP origins have been identified by a spatially specific technique. Our results show the need for revising the interpretation of the cochlear origins of high-level CAPs-ABR wave 1. NEW & NOTEWORTHY Cochlear compound action potentials (CAPs) and auditory brain stem responses (ABRs) are routinely used in laboratories and clinics. They are typically interpreted as arising from the cochlear region tuned to the stimulus frequency. However, as sound level is increased, the cochlear origins of CAPs from tone bursts of all frequencies become very wide and their centers shift toward the most sensitive cochlear region. The standard interpretation of CAPs and ABRs from moderate to intense stimuli needs revision.

Tuning to Interaural Time Difference and Frequency Differs Between the Auditory Arcopallium and the External Nucleus of the Inferior Colliculus

2009 ◽  
Vol 101 (5) ◽  
pp. 2348-2361 ◽  
Author(s):  
Katrin Vonderschen ◽  
Hermann Wagner
Keyword(s):  
Inferior Colliculus ◽  
Tuning Curve ◽  
Interaural Time Difference ◽  
Low Frequency ◽  
Steep Slope ◽  
Time Difference ◽  
Interaural Time Differences ◽  
Tuning Curves ◽  
Barn Owls ◽  
Zero Time

Barn owls process sound-localization information in two parallel pathways, the midbrain and the forebrain pathway. Exctracellular recordings of neural responses to auditory stimuli from far advanced stations of these pathways, the auditory arcopallium in the forebrain and the external nucleus of the inferior colliculus in the midbrain, demonstrated that the representations of interaural time difference and frequency in the forebrain pathway differ from those in the midbrain pathway. Specifically, low-frequency representation was conserved in the forebrain pathway, while it was lost in the midbrain pathway. Variation of interaural time difference yielded symmetrical tuning curves in the midbrain pathway. By contrast, the typical forebrain-tuning curve was asymmetric with a steep slope crossing zero time difference and a less-steep slope toward larger contralateral time disparities. Low sound frequencies contributed sensitivity to contralateral leading sounds underlying these asymmetries, whereas high frequencies enhanced the steepness of slopes at small interaural time differences. Furthermore, the peaks of time-disparity tuning curves were wider in the forebrain than in the midbrain. The distribution of the steepest slopes of best interaural time differences in the auditory arcopallium, but not in the external nucleus of the inferior colliculus, was centered at zero time difference. The distribution observed in the auditory arocpallium is reminiscent of the situation observed in small mammals. We speculate that the forebrain representation may serve as a population code supporting fine discrimination of central interaural time differences and coarse indication of laterality of a stimulus for large interaural time differences.

Masking of Tinnitus Compared to Masking of Pure Tones

1984 ◽  
Vol 27 (1) ◽  
pp. 106-111 ◽  
Author(s):  
Richard S. Tyler ◽  
David Conrad-Armes
Keyword(s):  
Tuning Curve ◽  
Low Frequency ◽  
Frequency Resolution ◽  
Signal Frequency ◽  
Frequency Range ◽  
Apparent Relationship ◽  
Pure Tones ◽  
Frequency Threshold ◽  
High Level ◽  
Tinnitus Masking

In 10 subjects with sensorineural tinnitus (associated with a sensorineural hearing loss and no apparent source for a tinnitus originating elsewhere), the minimum level required to mask the tinnitus was determined for tonal maskers at several masker frequencies. This tinnitus masking pattern was compared to a psychoacoustical tuning curve (PTC) in which the signal frequency and level were determined from tinnitus pitch and loudness matching. Different patterns emerged. One subject showed a near-normal PTC but required high-level maskers across the frequency range to mask the tinnitus. Another subject showed some frequency resolution in the PTC but required low-level maskers across the frequency range to mask the tinnitus. For the remaining eight subjects, the masker levels required to mask the tone were generally higher than those levels required to mask the tinnitus. In addition, it was noted that the tinnitus pitch-match frequency was sometimes associated with an increase or a decrease in threshold sensitivity, or it was found at the low-frequency edge of a steep high-frequency threshold loss. In other subjects there was no apparent relationship between the tinnitus pitch and the audiogram shape.

THE APPLICATION OF AUDIO‐FREQUENCY MAGNETOTELLURICS (AMT) TO MINERAL EXPLORATION

Geophysics ◽  
1973 ◽  
Vol 38 (6) ◽  
pp. 1159-1175 ◽  
Author(s):  
D. W. Strangway ◽  
C. M. Swift ◽  
R. C. Holmer
Keyword(s):  
Narrow Band ◽  
Mineral Exploration ◽  
Broad Band ◽  
Low Frequency ◽  
High Resistivity ◽  
Analog System ◽  
Conductivity Structure ◽  
Magnetotelluric Method ◽  
Audio Range ◽  
Considerable Experience

With the use of frequencies in the audio range, the magnetotelluric method can determine subsurface electrical conductivity structure at depths appropriate for mineral exploration. In 1963, Kennecott initiated a program to determine the feasibility of this technique as a geophysical tool. As opposed to the broad‐band recording and subsequent Fourier analysis commonly utilized in low‐frequency magnetotelluric studies, Kennecott’s AMT instrumentation is a multifrequency, narrow‐band, analog system which yields scalar apparent resistivities. Since the natural source fields at frequencies from 10 hz to about 20 khz are due to thunderstorm energy, the AMT technique is most useful in summertime operation, as is Afmag. Considerable experience in the field has led to useful applications in several problems: (a) uniform sedimentary columns, (b) high‐resistivity cover, and (c) massive, layered sulfides. Although of predictably little assistance in problems relating to disseminated mineralization exploration, deep targets, or areas with low‐resistivity cover, the AMT technique can be useful in defining sharp lateral contrasts in resistivity and in “seeing” through high‐resistivity cover.

Spatiotemporal Frequency Tuning Dynamics of Neurons in the Owl Visual Wulst

2010 ◽  
Vol 103 (6) ◽  
pp. 3424-3436 ◽  
Author(s):  
Lucas Pinto ◽  
Jerome Baron
Keyword(s):  
Striate Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Broad Band ◽  
Low Frequency ◽  
Emergent Properties ◽  
Response Latencies ◽  
Tuning Curves ◽  
Low Pass ◽  
Spatiotemporal Tuning

The transformation of spatial (SF) and temporal frequency (TF) tuning functions from broad-band/low-pass to narrow band-pass profiles is one of the key emergent properties of neurons in the mammalian primary visual cortex (V1). The mechanisms underlying such transformation are still a matter of ongoing debate. With the aim of providing comparative insights into the issue, we analyzed various aspects of the spatiotemporal tuning dynamics of neurons in the visual wulst of four awake owls. The wulst is the avian telencephalic target of the retinothalamofugal pathway and, in owls, bears striking functional analogy with V1. Most neurons in our sample exhibited fast and large-magnitude adaptation to the visual stimuli with response latencies very similar to those reported for V1. Moreover, latency increased as a function of stimulus SF but not TF, which suggests that parvo- and magno-like geniculate inputs could be converging onto single wulst neurons. No net shifts in preferred SF or TF were observed along the initial second of stimulation, but bandwidth decreased roughly during the first 200 ms after response latency for both stimulus dimensions. For SF, this occurred exclusively as a consequence of low-frequency suppression, whereas suppression was observed both at the low- and high-frequency limbs of TF tuning curves. Overall these results indicate that SF and TF tuning curves in the wulst are shaped by both feedforward and intratelencephalic suppressive mechanisms, similarly to what seems to be the case in the mammalian striate cortex.

Ectopic excitability of injured nerves in monkey: entrained responses to vibratory stimuli

1991 ◽  
Vol 65 (3) ◽  
pp. 693-701 ◽  
Author(s):  
G. M. Koschorke ◽  
R. A. Meyer ◽  
D. B. Tillman ◽  
J. N. Campbell
Keyword(s):  
Mechanical Stimulation ◽  
Frequency Tuning ◽  
Tuning Curve ◽  
Low Frequency ◽  
Frequency Range ◽  
Unit Recording ◽  
Injury Site ◽  
Tuning Curves ◽  
Frequency Group ◽  
Minimum Amplitude

1. The responses to mechanical stimulation of myelinated fibers that originate from an acutely cut nerve or a neuroma were studied in the anesthetized monkey. The superficial radial or sural nerve was tightly ligated and cut. Either immediately (acute experiment) or 2-6 wk later (chronic experiment), single-unit recording techniques were used to record the evoked neural activity after vibratory mechanical stimulation (5-100 Hz; 50-800 microns) near the injury site. 2. The 30 myelinated afferents studied in the chronic experiments displayed an entrained response (1 action potential for each stimulus cycle) to vibratory stimuli applied at or near the nerve injury site. For 19 fibers, the minimum amplitude for entrainment was determined as a function of frequency (tuning curve). For 11 others, complete tuning curves were not obtained, although the frequency range over which they were most sensitive could be estimated. The afferents could be classified into three groups on the basis of the frequency range over which they were most sensitive: 1) a low-frequency group that was most sensitive to frequencies less than or equal to 5 Hz (n = 7), 2) a mid-frequency group that was most sensitive to a broad range of frequencies (i.e., 20-75 Hz, n = 13), and 3) a high-frequency group that was most sensitive to frequencies greater than or equal to 100 Hz (n = 10). These three response classes are similar to the three classes of response associated with the different low-threshold mechanoreceptors (i.e., slowly and rapidly adapting and Pacinian-like mechanoreceptors).(ABSTRACT TRUNCATED AT 250 WORDS)

Noise-Induced Tuning Curve Changes in Mechanoreceptors

1998 ◽  
Vol 79 (4) ◽  
pp. 1879-1890 ◽  
Author(s):  
Chandra Ivey ◽  
A. Vania Apkarian ◽  
Dante R. Chialvo
Keyword(s):  
Tuning Curve ◽  
Signal To Noise Ratio ◽  
Signal Transmission ◽  
Low Frequency ◽  
External Noise ◽  
Sine Wave ◽  
Tuning Curves ◽  
Large Expansion ◽  
Typical Shape ◽  
Noise Input

Ivey, Chandra, A. Vania Apkarian, and Dante R. Chialvo. Noise-induced tuning curve changes in mechanoreceptors. J. Neurophysiol. 79: 1879–1890, 1998. Fibers from the tibial nerve of rat were isolated and spike activity recorded using monopolar hook electrodes. The receptive field (RF) of each recorded unit on the glabrous skin of the foot was mechanically stimulated with waveforms comprised of various frequency sine waves in addition to increasing levels of white noise. Single-unit responses were recorded for both rapidly adapting (RA) and slowly adapting (SA) units. Signal-to-noise ratio (SNR) of the output was quantified by the correlation coefficient ( C 1) between the input sine wave and the nerve responses. The addition of noise enhanced signal transmission in both RA and SA fibers. With increasing noise, the initially inverted “V”-shaped, zero-noise tuning curves for RA fibers broadened and eventually inverted. There was a large expansion of the frequencies that the RA receptor responded to with increasing noise input. On the other hand, the typical shape of the SA fiber tuning curves remained invariant, at all noise levels tested. C 1 values continued to increase with larger noise input for higher frequencies, but did not do so at the lowest frequencies. For both RA and SA fibers the responses with added noise tended to be rate modulated at the low-frequency end, and followed nonlinear stochastic resonance (SR) properties at the higher frequencies. The changes in the tuning properties due to noise found here, as well as preliminary psychophysics data, imply that external noise is relevant for sensing small periodic signals in the environment. All current models of sensory perception assume that the tuning properties of receptors determined in the absence of noise are preserved during everyday tasks. Our results indicate that this is not true in a noisy environment.

High-Level Psychophysical Tuning Curves

1991 ◽  
Vol 34 (6) ◽  
pp. 1233-1249 ◽  
Author(s):  
David A. Nelson
Keyword(s):  
Outer Hair Cell ◽  
Cell Function ◽  
Low Frequency ◽  
Normal Hearing ◽  
Hearing Impaired ◽  
Frequency Resolution ◽  
Tuning Curves ◽  
Fitting Procedures ◽  
Cochlear Hearing Loss ◽  
High Level

Forward-masked psychophysical tuning curves (PTCs) were obtained for 1000-Hz probe tones at multiple probe levels from one ear of 26 normal-hearing listeners and from 24 ears of 21 hearing-impaired listeners with cochlear hearing loss. Comparisons between normal-hearing and hearing-impaired PTCs were made at equivalent masker levels near the tips of PTCs. Comparisons were also made of PTC characteristics obtained by fitting each PTC with three straight-line segments using least-squares fitting procedures. Abnormal frequency resolution was revealed only as abnormal downward spread of masking. The low-frequency slopes of PTCs from hearing-impaired listeners were not different from those of normal-hearing listeners. That is, hearing-impaired listeners did not demonstrate abnormal upward spread of masking when equivalent masker levels were compared. Ten hearing-impaired ears demonstrated abnormally broad PTCs, due exclusively to reduced high-frequency slopes in their PTCs. This abnormal downward spread of masking was observed only in listeners with hearing losses greater than 40 dB HL. From these results, it would appear that some, but not all, cochlear hearing losses greater than 40dB HL influence the sharp tuning capabilities usually associated with outer hair cell function.

REFLECTED AND TRANSMITTED FILTER FUNCTIONS FOR SIMPLE SUBSURFACE GEOMETRIES

Geophysics ◽  
1976 ◽  
Vol 41 (6) ◽  
pp. 1305-1317 ◽  
Author(s):  
M. Schoenberger ◽  
F. K. Levin
Keyword(s):  
Thin Layer ◽  
High Frequency ◽  
Narrow Band ◽  
Broad Band ◽  
Low Frequency ◽  
Single Layer ◽  
High Amplitude ◽  
Shadow Zone ◽  
Least Energy ◽  
Very High

A zone of sands embedded in shale acts as a filter, both in reflecting energy back to the surface and in transmitting energy to reflectors below them. For a single layer of sand, the reflection filter is periodic—reflecting no energy at some frequencies and more than either of the two individual interfaces at other frequencies. Separating the sand zone into two parts by inserting a thin layer of shale results in reflection filters which differ greatly from one another. The particular filter curve generated depends upon the location of the shale layer. A sand zone filters reflections from interfaces below the zone in a manner complementary to the reflection filter. Where the most energy is reflected, the least is transmitted; conversely, where the least energy is reflected, the most is transmitted. The models considered in this report could easily give rise to high‐amplitude reflections; but, unless the amplitudes were very high, there would be little filtering of deeper reflections. However, for very high‐amplitude reflections and narrow‐band data, little energy would be transmitted and a shadow zone would result. For very high‐amplitude shallow reflections and broad‐band data, a low‐frequency shallow reflection would cause high‐frequency deep reflections; a high‐frequency shallow reflection would cause low‐frequency deep reflections.

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