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.

Does tinnitus originate from hyperactive nerve fibers in the cochlea?

1984 ◽  
Vol 98 (S9) ◽  
pp. 38-44 ◽  
Author(s):  
Richard S. Tyler
Keyword(s):  
Basilar Membrane ◽  
Tuning Curve ◽  
Nerve Fibers ◽  
Frequency Resolution ◽  
Signal Frequency ◽  
Physiological Data ◽  
Pitch Matching ◽  
Category Scaling ◽  
Tinnitus Masking ◽  
Peripheral Origin

AbstractThis paper discusses the possibility of a localized peripheral origin of tinnitus. A working hypothesis is that tinnitus represents either aperiodic or periodic hyperactivity in the spontaneous activity of nerve fibers originating from a restricted place on the basilar membrane. The limited physiological data available support both hyperactive and hypoactive nerve fiber. Psychophysical data are not easy to interpret. Subjective descriptions and category scaling are too dependent on individual experience. Pitch matching can be reliable, but cannot distinguish between peripheral or central tinnitus. In one experiment we compared the masking of tinnitus to the masking of a pure tone, where the signal frequency and level were obtained from the tinnitus pitch and loudness matching. The results indicate that the broad tinnitus masking patterns are not typically due to the poor frequency resolution observed in sensorineural hearing loss. However, in a few subjects there was some correspondence between the shape of the tuning curve and the tinnitus masking pattern. In another study, we masked tinnitus with narrowband noises of different bandwidths. In some patients, there was a ‘critical bandwidth’ effect; wider masker bandwidths required greater overall sound pressures to mask the tinnitus. We conclude that the results from these studies taken together indicate that there are different types of tinnitus, some of which may have a localized peripheral origin.

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.

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.

An L-Band Low Spurious Multi-Tuned Frequency Synthesizer

2013 ◽  
Vol 850-851 ◽  
pp. 441-444
Author(s):  
Fei Yan Mu ◽  
Bao Sheng Ye ◽  
Jie Lin ◽  
Zhong Jian Kang
Keyword(s):  
Frequency Synthesizer ◽  
Frequency Resolution ◽  
Frequency Range ◽  
Improve Performance ◽  
Loop Bandwidth ◽  
Spurious Suppression ◽  
Frequency Source ◽  
L Band ◽  
High Level ◽  
Better Than

This paper designs an L-Band 1880-1980 MHz low spurious Multi-tuned frequency synthesizer. The frequency source utilizes a DDS to directly stimulate a PLL, which makes a balance between the DDS and the PLL complementary to each other, realizing better specifications. Meanwhile, in order to achieve better spurious suppression with wide loop bandwidth, a method based on triple tuned algorithm is introduced. This algorithm avoids the high level spurious components triggered by the DDS falling in PLL’s bandwidth, refining the structure of the DDS-directly-stimulating PLL circuit frequency lock time and spurious to improve performance. The simulation result shows that the frequency source achieves a frequency range of 1880MHz～1980MHz, a frequency resolution of 1MHz, a spur better than 80dBc, a phase noise of -103dBc/Hz@100kHz and a frequency lock time less than 2 μs.

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.

Low Frequency High Level Noise Impulses near Weapons and Explosions

1988 ◽  
Vol 7 (2) ◽  
pp. 42-49 ◽  
Author(s):  
Rauno Paakkonen
Keyword(s):  
Frequency Domain ◽  
Impulse Noise ◽  
Energy Content ◽  
Low Frequency ◽  
Frequency Range ◽  
Frequency Peak ◽  
High Level ◽  
Peak Value

Analyses with a waveform analyser were made of the time and frequency domain of impulse noise from both military guns, e.g. rifles, cannons, bazookas and mortars, and explosions. For heavy weapons the most prominent energy content was found to be in the frequency range below 100 Hz. The frequency peak was generally less than 50 Hz. The significance for the A-weighting of noise impulses from weapons is discussed, as well as the different impulse parameters, e.g. peak value, impulse energy and A-duration.

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)

scholarly journals Strong influence of solar X-ray flares on low-frequency electromagnetic signals in middle latitudes

2019 ◽  
Author(s):  
Alexandr Rozhnoi ◽  
Mariya Solovieva ◽  
Viktor Fedun ◽  
Peter Gallagher ◽  
Joseph McCauley ◽  
...  
Keyword(s):  
Solar Flares ◽  
Low Frequency ◽  
Signal Frequency ◽  
Frequency Range ◽  
Effective Height ◽  
X Ray ◽  
Middle Latitudes ◽  
Burst Data ◽  
Path Lengths ◽  
Electromagnetic Signals

Abstract. In this paper we analysed Sudden Phase Anomalies (SPAs) of VLF/LF signals recorded at Graz (Austria), Birr (Ireland) and Moscow (Russia) stations during two strong solar flares in September 2017. The first X-class 9.3 flare occurred on 6 September at 12:02 UT and the second X-class 8.2 flare was observed on 10 September 2017 at 16:06 UT. Data from seven transmitters in a frequency range between 20–45 kHz are used for the analysis. The SPAs were observed in all middle-latitudes paths (differently orientated) with path lengths from 350 km to 7000 km. Solar X-ray burst data were taken from GOES satellite observations in the wavelength band of 0.05–0.4 nm. If was found that (i) the amplitude of SPAs in different paths varies from 10 to 282 degrees, and (ii) the correlation between the amplitudes of SPAs, the lengths of paths and the signal frequency is weak. The change in effective height of reflection due to lowering of the reflecting layer during the flares was found to be about 12 km for the first event and about 9 km for the second event. Spectral analysis of the X-ray and LF data, filtered in the range between 5 s and 16 min, showed that the LF signal spectra are very similar to X-ray spectra. Maxima of both X-ray and LF spectra are in 2–16 min interval.

scholarly journals A Study on the Relationship between Subjective Unpleasantness and Body Surface Vibrations Induced by High-level Low-frequency Pure Tones

2005 ◽  
Vol 43 (3) ◽  
pp. 580-587 ◽  
Author(s):  
Yukio TAKAHASHI ◽  
Kazuo KANADA ◽  
Yoshiharu YONEKAWA ◽  
Noriaki HARADA
Keyword(s):  
Body Surface ◽  
Low Frequency ◽  
Surface Vibrations ◽  
Pure Tones ◽  
High Level ◽  
The Relationship

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.

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