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Query: UMLS:C0234215 (discomfort)
 24,445 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relationships among most comfortable listening level (MCL), loudness discomfort level, and the acoustic reflex to speech were studied on normal-hearing listeners using earphones and sound field test conditions. Recorded sentence materials were presented monaurally in quiet and, in the sound field, in the presence of 55 dB SPL cafeteria noise. The results indicate the MCL in the quiet sound field at approximately 70 dB SPL with the acoustic reflex occurring at 16 dB higher intensity. The earphone MCL was 7 dB lower than in the sound field, a finding that may reflect a real reverse in usual earphone/sound field results or simply calibration factors particular to the speakers and test room used in this study. The AR to speech seems to occur at approximately equal intensities between the MCL and LDL tested in quiet. The MCL is elevated by noise whereas the acoustic reflex remains at a constant level, indicating that no absolute relationship exists between loudness and the AR.
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PMID:Loudness and the acoustic reflex: normal-hearing listeners. 42 27

The relationship between hearing level and loudness discomfort level (LDL) for narrow-band noise was evaluated in two groups of patients with sensorineural hearing loss. Group I had thresholds ranging from 25-60 dB SPL and Group II's thresholds ranged from 65-100 dB SPL. LDLs were determined for narrow bands of noise centered at 500, 1000, 2000, and 4000 Hz. The LDLs for Group II were greater than those for Group I and the differences were statistically significant. It is speculated that one reason for others not finding differences as a function of hearing level may be the absence of severe to profound hearing loss in the test populations.
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PMID:Evaluation of relationship between hearing threshold and loudness discomfort level in sensorineural hearing loss. 42 53

The relationships among most comfortable listening level (MCL), loudness discomfort level, and the acoustic reflex (AR) to speech were studied on cochlear-impaired listeners using earphones and sound field conditions. Recorded sentence materials were presented monaurally in quiet and in the sound field in the presence of 55 dB SPL cafeteria noise. Both unaided and aided sound field testing were done. The results indicated that the MCL and AR fell at approximately the same intensities under all test conditions, whereas the LDL occurred at approximately 18 dB higher intensity. The MCL was elevated by the presence of noise, whereas the AR remained invariant. Also, the AR occurred below the level predicted by the loudness function. The results tend to indicate that although the AR is highly correlated with MCL in cochlear-impaired listeners a cause and effect relationship may not exist.
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PMID:Loudness and the acoustic reflex: cochlear-impaired listeners. 51 65

Adaptive procedures were used to determine psychometric functions for loudness discomfort level (LDL) and most comfortable loudness (MCL) for pure tones and speech using normal and hearing-impaired listeners. For the LDL, both groups demonstrated steeply rising functions with the 50% point at approximately 100 dB SPL. The MCL data resulted in two functions, one (Function A) differentiating MCL from less intense stimulus levels and the second (Function B) differentiating between MCL and more intense levels. Function A may be considered a lower bound and Function B an upper bound for MCL. For the normal listeners, the difference between the functions at 50% response ranged from 9.9 to 19.9 dB depending upon the experimental condition. For the hearing-impaired subjects, this range was restricted to approximately 4.5 dB, primarily as a result of a shift in Function A toward higher sound pressure levels.
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PMID:Psychometric functions for loudness discomfort and most comfortable loudness levels. 100 44

In the present study we examined the relationship of the loudness discomfort level LDL of different signals. We carried out measurements in 97 patients, all of whom suffered from a sensorineural hearing loss. The results showed almost no difference between the LDL of pure tones and narrow band noise. The LDL of broad band noise showed a good correlation to the LDL of 250 Hz. Only the LDL of monosyllables ranged at a higher SPL. For an up-to-date hearing aid fitting, all forms of LDL should be taken into consideration. This is especially necessary when using digital hearing aids.
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PMID:[Various uncomfortable loudness thresholds, their correlation and use in general practice]. 146 66

Real-ear measurements of the aided Loudness Discomfort Level (LDL) were obtained from five hearing-impaired listeners who were fit with two Class A and two Class D linear hearing aids, each with a different saturation sound pressure level (HFA SSPL90). These measurements were obtained with 75 dB SPL continuous discourse to determine whether saturation-induced distortion contributes to the sensation of loudness. Real-ear coherence measurements made at LDL were used to determine the extent of saturation, and sound quality judgments were used to determine whether the distortion present at LDL affected sound quality. Results indicated that the SPL, coherence, and sound quality ratings obtained at LDL were all higher for Class D hearing aids with relatively high HFA SSPL90 than for Class A hearing aids with relatively low HFA SSPL90. Overall results were generally consistent with the hypothesis that distortion affects both sound quality and the perception of loudness.
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PMID:Hearing aid saturation, coherence, and aided loudness discomfort. 160 Feb 19

The threshold conditions for an auditory perception of pulsed radiofrequency (RF) energy absorption in the human head have been studied on six volunteers with RF coils for magnetic resonance (MR) imaging. For homogeneous RF exposure with MR head coils in the 2.4- to 170-MHz range and pulse widths 3 microseconds less than or equal to Tp less than 100 microseconds, the auditory thresholds were observed at 16 +/- 4 mJ pulse energy. Localized RF exposure with optimized surface coils positioned flush with the ear lowers the auditory threshold to only 3 +/- 0.6 mJ. The hearing threshold of RF pulses with Tp greater than 200 microseconds occurs at more or less constant peak power levels of typically 150 +/- 50 W for head coils and as low as 20 W for surface coils. The results from this study confirm theoretical predictions from a thermoelastic expansion model and compare well with reported thresholds from near field antenna measurements at 425 to 3000 MHz. Details of the threshold dependence on RF pulse length reveal primary sites of RF to acoustic energy conversion at the mastoid and temporal bone region and the outer layer of the brain from where thermoelastically generated pressure transients excite audible pressure waves at the resonance modes of the skull around 1.7 kHz and of the brain around 11 kHz. If not masked by usually dominating noise from switched gradients, the conditions for hearing RF pulses, as applied to head coils in MR studies with flip angle alpha at main field B0, is given by Tp/ms less than or equal to 0.4 (alpha/pi)B0/[T]. At peak power levels up to 15 kW presently available in clinical MR systems, there is no evidence known for detrimental health effects arising from the RF auditory phenomenon which is a secondary cause associated with primary RF to thermal energy conversion in body tissues. To avoid the RF-evoked sound pressure levels in the head rising above the discomfort threshold at 110 dB SPL, an upper limit of 30 kW applied peak pulse power is suggested for head coils and 6 kW for surface coils.
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PMID:Human auditory system response to pulsed radiofrequency energy in RF coils for magnetic resonance at 2.4 to 170 MHz. 174 19

A new procedure is described for measuring loudness discomfort levels (LDLs) for the purpose of selecting SSPL90 characteristics of hearing aids. The person is seated in sound field wearing a high-output hearing aid (with a known amount of 2 cm3 coupler gain) connected to a personal earmold. The loudness of frequency-specific signals is rated from a series of loudness category descriptors. The LDL is defined in terms of SPL developed in a 2 cm3 coupler, thus making selection of SSPL90 from hearing aid specification sheets practical. Experiments on LDL stability over time and validation of the SSPL90 selection are reported.
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PMID:Description and validation of an LDL procedure designed to select SSPL90. 360 12

Acoustic-reflex growth functions and Loudness-Discomfort Level (LDL) measures were obtained for 15 normal-hearing subjects. The hypothesis that signals considered uncomfortably loud occur at intensity levels that produce proportionately equal acoustic-reflex magnitudes was evaluated. Individual reflex growth functions were measured as a function of activator SPL for a 1000-Hz tone, a 4000-Hz tone, and a broadband noise. These growth functions were measured within subjects (two trials) and across subjects in terms of (a) percentage acoustic-impedance change at LDL, (b) percentage acoustic-reactance change at LDL, (c) acoustic impedance at LDL, (d) relative change in acoustic impedance at LDL, and (e) ratio of static acoustic impedance to change in acoustic impedance at LDL. Although the loudness and acoustic-reflex measures demonstrated good reliability across trials, the data showed large variability across subjects and did not support the experimental hypothesis. It was concluded, therefore, that the use of acoustic-reflex measures in the estimation of an individual's LDL is unwarranted.
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PMID:Acoustic-reflex dynamics and the loudness-discomfort level. 397 7

The acoustical problems involved in matching the saturation sound pressure level for a 90 dB input signal (SSPL90) of a hearing aid to individual discomfort level were investigated. The real ear SPL (RE/SSPL90) produced by a supra-aural earphone used when measuring uncomfortable loudness (UCL), and RE/SSPL90 produced by three different hearing aids at 90 dB SPL input, were measured for nine subjects, using a miniature microphone technique, and compared to the corresponding coupler levels used when matching hearing aid maximum output to UCL. It was found that a hearing aid often gives about 5 dB, and sometimes 10 dB, higher RE/SPLs than the earphone, if the hearing aid output levels, as measured in a 2-cc coupler (IEC126), are equal to the earphone output levels as measured in a 6-cc coupler (NBS9A). It is recommended that a safety margin of at least 5 dB be used in the preliminary fitting when matching hearing aid SSPL90 to the patient's UCL, converted to dB SPL.
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PMID:Audiometric earphone discomfort level and hearing aid saturation sound pressure level for a 90 decibel input signal (SSPL90) as measured in the human ear canal. 661 37


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