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Results for “Auditory Threshold”

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PubMed1993

The sensitivity to 3,3'-iminodipropionitrile differs for high- and midfrequency hearing loss in the developing rat.

3,3'-Iminodipropionitrile (IDPN) has been demonstrated to produce a loss of hearing following both neonatal and adult exposures. Adult exposure induces a full spectrum hearing loss, whereas early postnatal exposure produces a high-frequency loss only. The purpose of this work was to delineate the period of development during which the rat becomes sensitive to the full ototoxic effects of IDPN. Primiparous Long Evans rats or their offspring were exposed to either saline or 300 mg/kg IDPN for three consecutive days. Ages of exposure were as follows: gestational days 15-17 or postnatal days (PND) 1-3, 5-7, 15-17, 20-22, 25-27, 30-32, 40-42, or 70-72. All animals were tested as adults for auditory thresholds to 5- and 40-kHz tones using reflex modification audiometry. Results demonstrate that adult-like susceptibility to IDPN was not reached until approximately PND 30-32. Early exposures (PND 5-22) to IDPN will induce a highfrequency selective hearing loss, sparing the lower frequency. Prenatal or early neonatal (PND 1-3) IDPN exposure resulted in a high degree of mortality (> 70%). The long period of time between the susceptible period for the high frequency (PND 5-7) and the lower frequency (PND 30-32) does not correspond to the basal to apical ontogenic profile of any one physiological or anatomical process. These data suggest either a unique site of action for IDPN in the cochlea or the possibility of two different mechanisms, one operating at early postnatal ages and one at later ages.

Acoustic Stimulation↗

PubMedDate not supplied

Bone conduction variation poststapedotomy.

We evaluated the variation in bone conduction auditory thresholds in patients undergoing surgical intervention for otosclerosis as part of our report on the use of surgery in patients with a small air-bone gap. Of the 110 patients who underwent stapedotomy, 45 were treated by traditional surgery and 65 with carbon dioxide laser, with a follow-up of 3 years at 500-, 1000-, 2000-, and 3000-Hz frequencies. Both surgical techniques resulted in improvements in air conduction in more than 95% of cases; bone conduction improved more in patients treated with carbon dioxide laser (7.1 dB) compared to those treated with traditional surgery (4 dB) (P < .01). Furthermore, improvement in bone conduction was greater and more frequent in younger subjects (below 45 years) (P < .05). In conclusion, this study allows us to express a positive prognosis when considering otosclerotic patients with sensorineural hearing loss and small air-bone gap.

Adult↗

PubMed1982

The effects of the transcendental meditation and TM-Sidhi program on the aging process.

To evaluate the effects of the Transcendental Meditation (TM) and TM-Sidhi program on the aging process, a standardized test of biological aging, utilizing auditory threshold, near point vision, and systolic blood pressure, was given to a cross-sectional group (N = 84) with a mean age of 53 years. There were 11 controls, 33 short-term TM and TM-Sidhi participants, and 40 long-term participants. The mean biological age of the controls was 2.2 years younger than for the general population; of the short-term TM subjects, 5.0 years younger; of the long-term TM subjects, 12.0 years younger. The difference between the groups was significant covarying for a diet factor. Also, there was a significant correlation between length of time practicing the TM program and biological age (r = -0.46). Together with numerous physiological and psychological studies conducted on the TM and TM-Sidhi program, this study suggests that the TM program may affect certain neural mechanisms which in turn influence age correlated physiological variables.

Adult↗

PubMed1987

[Auditory adaptation and auditory fatigue].

Twenty subjects without otological disease were examined for auditory thresholds by Békésy audiometry and by the Feldmann Test (Adaptogramm), before and after noise exposure to one ear of 90 db SPL at 3 kHz for 15 minutes. The exposed ear was also tested for hearing fatigue (TTS). There was no significant correlation between Békésy audiometry and Feldmann test curves or between these adaptation tests and the hearing fatigue test (TTS) after noise exposure. Our results suggest that these methods of measuring adaptation do not correspond, and that adaptation measurements, prior to noise exposure, have no predictive value for hearing fatigue test results following noise exposure. After noise exposure changes were found in the non-exposed ear which were manifested as variability of the Békésy audiometry curves and flattened Feldmann curves. We thought that these results might indicate a central adaptation following noise exposure. There was interference of this so called "central adaptation" with peripheral fatigue in the exposed ear.

Audiometry, Pure-Tone↗

PubMed2002

Changes in auditory sensitivity with depth in a free-diving California sea lion (Zalophus californianus).

All current data on underwater hearing in pinnipeds are based on tests conducted in small tanks, and may not accurately represent the auditory functioning of free-ranging animals, especially if hearing sensitivity changes with water depth. Underwater auditory thresholds were determined for a California sea lion at depths ranging from 10 to 100 meters. The following results were obtained: (1) False alarm probabilities (responding in the absence of a signal) decreased significantly with depth, indicating that the sea lion adopted a more conservative response criterion in deeper water. (2) Hearing sensitivity generally worsened with depth. (3) There was a significant interaction between depth and frequency, the depth effect being most pronounced at 10 kHz and reversing at 35 kHz. Increasing pressure related to diving probably alters the impedance characteristics of the pinniped ear, in particular affecting the size of the middle-ear air space via expansion of cavernous tissue in the middle-ear cavity. These results show that the middle ear plays a functional role in underwater sound detection in sea lions. However, contrary to previous speculation, the presence of cavernous tissue in the sea lion middle ear does not appear to enhance sensitivity at depth.

Animals↗

PubMed2006

Clinical, etiological and progression factors of hearing in sudden deafness.

UNLABELLED: Out of the many forms of therapy for sudden deafness, some require hospitalization and present significant risks. AIM: This prospective study analyzes etiology and evolution in cases of sudden deafness (SD) where outpatient oral treatment was used. STUDY DESIGN: Clinical with transversal cohort. MATERIAL AND METHOD: Forty cases of sudden hearing loss were followed for at least one year. All were submitted to initial clinical evaluation, auditory tests, routine blood analysis, and magnetic resonance imaging. All received initial treatment with pentoxifylline and prednisone. RESULTS: 45% (n=18) presented normal auditory thresholds, 40% (n=16) showed some improvement in hearing, 15% (n=6) maintained initial hearing level. Nine cases (22.5%) presented clinical conditions possibly implicated in hearing loss (viral infection, immunomediated hearing loss, vascular disorders, and so on); three (7.5%) had cerebellopontine tumors. Evolution of hearing in these 12 cases with presumed etiology presented no differences from hearing in the 28 cases without any known etiological factor. Clinical treatment within the first seven days was the only statistically significantly different condition in patients who improved hearing. CONCLUSIONS: An objective search for etiological bases should be conducted in any case of acute sensorineural hearing loss. The presence of cerebellopontine tumors in 7.5% of cases of SD, among other treated causes, justifies a thorough clinical investigation in these patients. Overall good evolution of hearing was observed in 67.5% of cases of SD, regardless of its etiology. Therapy within the first seven days of SD was significantly related to better outcomes in hearing.

Adolescent↗

PubMed2000

PCBs, thyroid hormones, and ototoxicity in rats: cross-fostering experiments demonstrate the impact of postnatal lactation exposure.

Previous research has demonstrated the sensitivity of the developing rat to the hypothyroxinemic and ototoxic effects of perinatal exposure to Aroclor 1254 (A1254). We tested the hypothesis that postnatal exposure via lactation is the major cause of the ototoxicity by cross fostering animals at birth. Primiparous rats (22-24/dose) received 0 or 6 mg/kg A1254 (po in corn oil) from gestation day (GD) 6 to postnatal day (PND) 21. On the day of birth, half of the treated litters and half of the control litters were cross-fostered, resulting in the following groups: Ctrl/Ctrl (controls); A1254/A1254 (perinatal exposure); A1254/Ctrl (prenatal exposure only); and Ctrl/A1254 (postnatal exposure only). We assessed offspring at a number of ages for: serum thyroid hormone concentrations, liver and brain concentrations of PCBs, body weight, mortality, age of eye opening, auditory startle amplitudes, and auditory thresholds for 1 kHz and 40 kHz tones. Circulating thyroxine (T(4)) concentrations were sharply reduced at GD 21 in the A1254-exposed group, and on PND 3, 7, 14, and 21 in the A1254/A1254 and the Ctrl/A1254 groups. Smaller decreases in T(4) were observed in the A1254/Ctrl group on PND 3, 7, and 14. PCB concentrations in the liver on PND 21 were sharply elevated in the A1254/A1254 and Ctrl/A1254 groups. Much smaller increases were seen in the A1254/Ctrl group. Age of eye-opening and startle amplitudes were unaffected by treatment. A1254 exposure caused permanent hearing deficits (20 dB increase) at the low frequency (1 kHz) in the A1254/A1254 and Ctrl/A1254 groups. The present findings demonstrated that the critical period for the ototoxicity of developmental A1254 exposure is within the first few postnatal weeks in the rat. This effect is consistent with the greater degree of postnatal hypothyroxinemia resulting from the greater magnitude of exposure that occurs postnatally via lactation.

Aging↗

PubMed1998

[Experimental studies of the protective effect of deferoxamine mesilate on cisplatin induced toxicity].

Cisplatin (CDDP) is an antitumor agent against several types of neoplasms. It has, however, various side effects such as nephrotoxicity and ototoxicity. Several efforts have been made to prevent these toxic side effects. On the other hand, deferoxiamine mesilate (DFO), an iron-chelating agent, has been used for iron-overloaded patients. Since the 1980s, many authors have reported DFO-associated hearing impairment. Some experimental data suggest that DFO itself was responsible for ototoxicity. In addition, it has also been recognized that DFO can act as a free radical scavenger. Experimental trials using DFO are also expected to prevent CDDP-induced toxicity because its generation mechanism is thought to be associated with free radical formation. The present study was planned to investigate whether DFO, which might be an ototoxic agent, had a protective effect against various CDDP-induced toxicities including ototoxicity. Fisher rats were used in this study and were divided into four groups: 1) Group I, a vehicle control, 2) Group II, animals receiving 100 mg of DFO per kg, 3) Group III, animals administered 0.9 mg of CDDP per kg alone and 4) Group IV, animals receiving 100 mg of DFO per kg 60 min before 0.9 mg of CDDP per kg for 10 days. First, the protective effect of DFO against CDDP-induced ototoxicity was studied. The auditory threshold was determined by using the compound action potential (CAP) from the round window membrane. CAPs were recorded on the 5th day after completion of drug administration. Then CAPs recording, cochlear sensory epithelia were observed over all the turns of the cochlea by scanning electron microscopy. There were no significant differences in CAP thresholds between Group I and IV, though the thresholds in Group III were significantly higher at 16 kHz and 20 kHz than those in Group IV. The rate of missing outer hair cells in Group IV was significantly lower than that in Group III. The results clearly demonstrated that DFO had a protective effect against CDDP-induced ototoxicity. Second, the protective effect of DFO against CDDP-induced nephrotoxicity was studied. Renal function was evaluated by measuring blood urea nitrogen (BUN) and serum creatinine (Cr) levels. Both BUN and Cr levels in Group IV were significantly lower than those in Group III. The data suggested that DFO preadministration prevented CDDP-induced nephrotoxicity. Third, the influence of DFO on the antitumor activity of CDDP was investigated in rats inoculated with squamous cell carcinoma cells (SCC-131) subcutaneously. The influence of drugs was determined by measuring the tumor growth rate. There was no difference in the tumor growth rate between Group III and IV. The result revealed that DFO had no influence on CDDP antitumor activity. In conclusion, the above results demonstrating that DFO preadministration can prevent both CDDP-induced ototoxicity and nephrotoxicity without attenuation of CDDP antitumor activity, suggest the usefulness of CDDP antitumor chemotherapy.

Animals↗

PubMed1999

Improving speech audibility with wide dynamic range compression in listeners with severe sensorineural loss.

OBJECTIVE: In contrast to fitting strategies for linear amplification, which have been refined frequently for listeners with different degrees of hearing loss, we know relatively little about the effects of wide dynamic range compression (WDRC) amplification for listeners with severe auditory thresholds. The primary objective of this study was to determine if increases in audibility with WDRC amplification improved speech recognition to a comparable degree for listeners with different degrees of hearing loss. DESIGN: Listeners with mild to moderate or severe sensorineural loss were tested on recognition of vowel-consonant-vowel (VCV) syllables and sentences digitally processed with linear and WDRC amplification. The speech materials were presented under conditions of controlled audibility, in which WDRC amplification improved speech audibility over linear amplification. Presentation levels were chosen to provide equivalent increases in audibility with WDRC amplification for both listener groups. A control condition in which audibility was equated for the two amplification conditions was also included. RESULTS: Recognition results for VCV stimuli indicated that both listener groups received the same benefit from the improved audibility provided by WDRC amplification. Results for sentence recognition showed a greater benefit of WDRC amplification for listeners with mild to moderate than for listeners with severe loss. CONCLUSIONS: Increasing the amount of audible speech information with WDRC has similar effects on consonant recognition for listeners with different degrees of hearing loss. Differences in sentence recognition for listeners with different degrees of loss may be due to processing effects or to differences in available acoustic information for longer segments of WDRC-amplified speech.

Adult↗

PubMed2006

The pattern of sensory processing abnormalities in autism.

The study was undertaken to evaluate the nature of sensory dysfunction in persons with autism. The cross-sectional study examined auditory, visual, oral, and touch sensory processing, as measured by the Sensory Profile, in 104 persons with a diagnosis of autism, 3-56 years of age, gender-and age-matched to community controls. Persons with autism had abnormal auditory, visual, touch, and oral sensory processing that was significantly different from controls. This finding was also apparent when the high and low thresholds of these modalities were examined separately. At later ages for the group with autism, lower levels of abnormal sensory processing were found, except for low threshold touch, which did not improve significantly. There was a significant interaction in low threshold auditory and low threshold visual, suggesting that the two groups change differently over time on these variables. These results suggest that sensory abnormalities in autism are global in nature (involving several modalities) but have the potential to improve with age.

Adolescent↗

PubMed1979

Temporary threshold shift, loudness, and auditory evoked potentials.

TTS2 of 20dB was produced in a group of subjects using a 1000 Hz pure tone. All TTS and related measurements were made at 1500 Hz. The recovery of TTS, and of TLS or 'temporary loudness shift' (measured against a reference tone at 20db, 40dB and 60dB SL in the opposite ear), as well as N1-P2 amplitude of the Vertex potential, were plotted. There was an orderly recovery of both TLS and TTS although the rate of recovery of the latter was noticeably more rapid. Recovery of N1-P2 amplitude was much less orderly, although it did recover in much the same way. When the amplitudes were measured at 40dB SL the recovery was more orderly and followed the course of TTS more closely. It was concluded that any relation between N1-P2 amplitude and growth of loudness was indirect.

Acoustic Stimulation↗

PubMed1991

[Study of the cochlea by evoked otoemissions. Physiological interpretation of results].

Amplitudes and detection thresholds of evoked otacoustic emissions (EOE) were measured in various groups of subjects: 44 normal young adults, 80 patients with presbycusis and 38 patients with acoustic trauma. Relations between these EOE parameters and tonal audiogram were analyzed. Surprisingly, EOE detection threshold at 1 kHz was strongly correlated with auditory threshold at 2 kHz and no other one. This result demonstrates that some EOE parameters are not frequency-specific. A simple model is implemented in which it is assumed that EOE amplitudes are proportional to the global cochlear activity. This model fits very well experimental data and allows a quantitative evaluation of the residual cochlea. The domain of validity of EOE test in clinics has therefore been precised.

Audiometry↗

PubMed1991

The effects of Carbogen, carbon dioxide, and oxygen on noise-induced hearing loss.

An investigation into the effect of Carbogen (95% O2/5% CO2), 5% CO2/air, and 100% oxygen on cochlear threshold shifts caused by noise was undertaken. Five groups of eight pigmented guinea pigs were exposed to 105 dB broad band noise for 6 h per day for five consecutive days with each group receiving the various gaseous mixtures either during noise exposure or for 1 h immediately after noise exposure. A control group received the same noise exposure but respired air. Auditory threshold shifts, as measured by the auditory evoked brainstem response, were measured at 2,4,8,12,16, 20 and 24 kHz. Recordings were taken pre-exposure and at Day 1, 3, 5, and Weeks 2 and 3 after noise exposure. Carbogen, given during noise exposure, resulted in a trend toward less post noise exposure threshold shift (as compared to controls) which reached statistical significance by Week 3 at all frequencies except 2 and 20 kHz. Subjects given Carbogen after exposure also showed a general trend toward decreased noise induced threshold shifts, as compared to controls, but this was not statistically significant. The mixture of 5% CO2/air given during noise exposure yielded no difference in threshold shifts as compared to controls. When 100% oxygen was administered during noise exposure, a marked decrease in noise induced threshold shifts could be seen as compared to controls, with differences reaching statistical significance by day 5 at most frequencies. These results indicate that oxygen (i.e. cochlear-oxygenation) is a more important factor than CO2 (i.e., as a vasodilator) in protection of the cochlea from noise induced damage.

Animals↗

PubMed1989

The relation among hearing loss, sensory cell loss and tuning characteristics in the chinchilla.

Evoked-potential tuning curves were obtained on over 150 chinchillas before and after acoustic overstimulation in order to relate the effects of changes in frequency selectivity to sensory cell loss over a wide range of hearing loss. Pre- and post-exposure measures of auditory thresholds and masked thresholds (simultaneous tone-on-tone paradigm) were obtained in each animal at 0.5, 1.0, 2.0, 4.0, 8.0 and 11.2 kHz, using the auditory evoked potential recorded from the inferior colliculus. Three tuning curve variables (Q10dB, low-frequency slope and high-frequency slope) were compared to the amount of noise-induced permanent threshold shift and to the percent sensory cell loss produced by a variety of noise exposures. Based upon large sample averages, frequencies showing permanent threshold shifts in excess of 10 dB also showed statistically significant differences between pre- and post-exposure measures of all three tuning curve variables. Shifts of less than 10 dB were not accompanied by statistically significant changes in the tuning curve variables. The percentage of outer hair cell loss, and percentage change in tuning curve characteristics showed systematic and parallel increases as threshold shifts increased at all probe tone frequencies except 8.0 and 11.2 kHz. In general, the results were consistent in showing that there is a systematic change in the variables which define the quality of tuning as hearing loss progressively increases and that these changes are clearly related to outer hair cell losses.

Acoustic Stimulation↗

PubMed2000

Longitudinal threshold changes in older men with audiometric notches.

Age-related hearing loss (presbycusis) is a multifactorial process that results chiefly from the accumulating effects of noise damage and aging on the cochlea. Noise damage is typically evidenced clinically by a discrete elevation (notch) of the auditory thresholds in the 3-6 kHz region of the audiogram whereas aging affects the highest frequencies first. To determine whether the presence of such high-frequency notches influences auditory aging, we examined the 15 year change in audiometric thresholds in 203 men from the Framingham Heart Study cohort. The mean age at the first hearing test was 64 years (range 58-80). Occupational and recreational noise exposure over the 15 years was assumed to be minimal due to the age of the subjects. The presence or absence of a notch was determined using a piecewise linear/parabolic curve fitting strategy. A discrete elevation of the pure-tone thresholds of 15-34 dB in the 3-6 kHz region was deemed a small notch (N1), and elevations of 35 dB or greater were deemed large notches (N2). Absence of a notch (N0) was encoded those ears with <15 dB elevation in the 3-6 kHz region. The presence and absence of notches correlated with the subjects' history of noise exposure. The 15 year pattern of change in age-adjusted pure-tone thresholds varied significantly by notch category. There was less change over time in the notch frequencies (3-6 kHz) and significantly greater change in the adjacent frequency of 2 kHz in the N2 group as compared to the N0 and N1 groups. The adjacent frequency of 8 kHz showed a significant, but smaller, change in the N1 group as compared to the N0 and N2 groups. The change at 2 kHz was independent of the starting hearing level at E15, whereas the changes at 4-8 kHz were influenced by the hearing level at E15. These data suggest that the noise-damaged ear does not 'age' at the same rate as the non-noise damaged ear. The finding of increased loss at 2 kHz suggests that the effects of noise damage may continue long after the noise exposure has stopped. The mechanism for this finding is unknown but presumably results from prior noise-induced damage to the cochlea.

Aged↗

PubMed1992

Rapid development of the auditory brainstem response threshold in individual ferrets.

The development of the ferret auditory system was examined using the auditory brainstem response (ABR). Longitudinal recordings were obtained under short-acting anaesthesia from individual animals at 4-h or 24-h intervals. Particular attention was focused on the period from postnatal day (P) 26 to P32 when the ferret auditory system becomes functional. ABR thresholds to click stimuli presented in a free-field were found to decline precipitously within a 4-h period during the first 24 h following initial responsiveness. Latencies of waves I and IV of the ABR also declined significantly during this period, but the 'central conduction time' remained stable. A temporal correlation was observed between the time of the precipitous threshold decline and the time of opening of the external ear canal. No changes in cochlear anatomy were observed during this time. We suggest that the opening of the ear canal and/or the clearance of fluid from the middle ear explain the major change in threshold of hearing following onset of function.

Aging↗

PubMed2003

Estimation of hearing loss in children: comparison of auditory steady-state response, auditory brainstem response, and behavioral test methods.

The current pediatric test battery is limited in the severe-to-profound hearing loss range by the inability to obtain frequency-specific thresholds. Auditory steady-state response (ASSR) is an evoked potential test that can accurately measure auditory sensitivity beyond the limits of other test methods. The limited amount of clinical research, however, has delayed the acceptance of ASSR into the standard pediatric test battery. This study compared thresholds from 76 children using ASSR, ABR, and behavioral test methods. Resulting correlations were strong and supported the inclusion of ASSR into the standard pediatric test battery. ASSR testing provides audiometric information that is essential in the management of children with severe-to-profound hearing loss.

Audiometry, Pure-Tone↗

PubMed1995

Hearing loss in Paget's disease of bone: evidence of auditory nerve integrity.

Auditory brainstem responses (ABRs) were recorded in 64 ears with radiographically confirmed Paget's disease involving the skull. Responses were absent in eight ears, all of which had elevated high pure-tone thresholds. Auditory brainstem responses were interpreted as normal in 56 ears; none were abnormal. Computed tomography and digital image analysis were used to quantify internal auditory canal (IAC) dimensions. The midlength diameter and minimum diameter of the IAC of 68 temporal bones from subjects with Paget's disease were found to have no statistically significant relation to hearing thresholds. Increased IAC length showed a limited relation to reduced hearing level in pagetic subjects, possibly consistent with bossing adjacent to the porus acusticus. Findings support the principle that hearing loss in Paget's disease of bone is generally associated with intact auditory nerve function and also support a cochlear site of lesion.

Audiometry, Pure-Tone↗