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At least 1,153 records · Page 64Linked to original sources
PubMedDate not supplied

Improving the reproducibility of acoustic rhinometry in the assessment of nasal function.

Acoustic rhinometry readings are very position dependent, and it was hypothesized that this accounts for its relative lack of reproducibility on a day-to-day basis. Multiple readings on each visit were taken to investigate their impact, if any, on improving the day-to-day reproducibility of the method. Measurements of the minimal cross-sectional area of the nose as measured by acoustic rhinometry were studied in 10 subjects following nasal decongestion. For each individual, acoustic rhinometry was performed ten times. The ten recordings were repeated again, in an identical manner on a separate day. The subjects were repositioned and the nasal probes reinserted between each measurement. The mean coefficient of variation for minimal cross-sectional area readings in all 10 subjects was calculated as 9.92%. This is comparable to the day-to-day variability of acoustic rhinometry as measured by other workers and thus supports the hypothesis that the high measurement error of the device (rhinometer) is a function of positional variation during data acquisition. We were able to demonstrate a minimal gain in intervisit reproducibility by doing multiple recordings per person, with a plateau effect of reproducibility after 7 repeat readings.

Humans↗
PubMed1998

Gamma knife treatment of acoustic neurinoma.

The results of treatment of acoustic neurinomas using Gamma Knife radiosurgery (GKR) during a 6-year period in our center were reviewed. Since May 7, 1990, we treated 88 cases of acoustic neurinoma with GKR. During a 52-month mean follow-up period, MRI was obtained in 63 patients. Reduction in tumor size occurred in 34 (54%) cases, and another 27 (42.8%) tumors showed no change. The tumor control rate was thus 95%. Tumor size increased in 3 (4.8%) cases, but one case is still in early follow-up. Two cases were operated after GKR. Histological examination of the tumors removed at surgery 8 months after GKR were obtained. The examinations showed enlargement of nucleoli and cytoplasm and proliferation of endothelial cells due to delayed radiation changes. Post-GKR facial neuropathy was noted in 7 (8.8%) patients, of which 4 recovered during the follow-up period. The tumor volume, margin dose, number of isocenters and marginal isodose did not have any statistically significant relationship with the development of facial neuropathy. Transient trigeminal neuropathy were noted in 3 patients. Hearing was preserved in 2 of 3 hearing patients. In conclusion, our GKR results for acoustic neurinomas were very similar to the previously reported series, which makes GKR for acoustic tumors an excellent treatment modality for small- to medium-sized tumors with or without microsurgical tumor removal.

Adolescent↗
PubMed1998

Stereotactic radiosurgery toxicity in the treatment of intracanalicular acoustic neuromas: the Seattle Northwest gamma knife experience.

Patients with acoustic neuromas have several treatment options. The appropriate individual treatment decision and expected control rates and risks for the individual techniques have been outlined in several texts [1-4, 6-8]. This article describes radiosurgery toxicity in those patients with acoustic neuromas who have intracanalicular disease. 52 patients with 54 acoustic neuromas were treated between September 1993 and April 1997. 14 tumors were intracanalicular lesions, with a mean diameter <1 cm and volume <1 cm3. Dose to the periphery of the intracanalicular lesion extension ranged from 12-18 Gy (mean 16 Gy). The margin isodose was 40-60% (mean 47%). 32 isocenters were used to treat the 14 intracanalicular tumors (mean 2.3 isocenters per patient). At a mean follow-up of 18 months (range 1-39 months), 12/12 or 100% of the intracanalicular lesions demonstrated regression or no change in size on subsequent imaging. The following acute side effects were observed posttreatment in intracanalicular tumors: diminished hearing 14%, facial neuropathy 43%, trigeminal neuropathy 21%, balance disorder 14%, dizziness 7%, and headache 7%. Facial and trigeminal neuropathy, balance disorder, dizziness, vertigo and headaches were more common in patients with intracanalicular tumors than those with an extracanalicular extension. Although it has been suggested that small acoustic neuromas (i.e. <1 cm3) tolerate doses of 18 Gy with acceptable toxicity, when the lesion is located in the auditory canal a lesser dose may be warranted to minimize potential side effects. For now, our center has established a protocol that limits radiosurgical stereotactic intracanalicular peripheral doses to 12 Gy until further toxicity studies have been collected and reviewed.

Cranial Nerve Diseases↗
PubMedDate not supplied

Acoustic modulation of electrically evoked otoacoustic emission in chickens.

Electrically evoked otoacoustic emissions (EEOAEs) can be elicited from the chicken inner ear. Since lesion studies implicate hair cells are the source of EEOAEs, we hypothesized that acoustic stimuli would modulate EEOAE amplitude at cochlear locations where the acoustic and electrical stimuli overlap. To assess this interaction, EEOAEs were measured as the frequency and amplitude of the acoustic stimuli were varied. EEOAEs, evoked by AC current (3-250 microA rms) delivered to the round window had a broad band pass response (1-6 kHz) with a peak between 3 and 4 kHz and maximum amplitude of 27 dB SPL. EEOAE suppression/enhancement tuning curves were measured at 2, 3, 4 and 6 kHz by varying the frequency of a 70 dB SPL tone and measuring the change in EEOAE amplitude. EEOAE tuning curves were characterized by a tip; a narrow range of frequencies where EEOAE amplitude was suppressed by as much as 5 dB, and by sidebands, a range of frequencies above and below the tip where EEOAE amplitude was enhanced by as much as 1.5 dB. The best suppression frequency, or characteristic frequency, was close to the frequency of the EEOAE elicited by the 3- or 4-kHz electric stimulus. However, the characteristic frequency was displaced towards higher frequencies for the 2-kHz electric stimulus, and towards lower frequencies for the 6-kHz electric stimulus. EEOAE suppression increased approximately linearly with acoustic level. These results suggest that EEOAEs evoked by round window stimulation are predominantly generated by hair cells near the 3- to 4-kHz region of the cochlea.

Acoustics↗
PubMedDate not supplied

Acoustic investigation of vocal quality following treatment for childhood cerebellar tumour.

The aim of the study was firstly to document the acoustic parameters of voice using the Multidimensional Voice Program (MDVP, Kay Elemetrics) in a group of children with dysarthria subsequent to treatment for cerebellar tumour (CT). Then, secondly, compare the acoustic findings to perceptual voice characteristics as described by the GIRBAS (grade, instability, roughness, breathiness, asthenicity, strain). The assessments were performed on 29 voice samples; 9 cerebellar tumour participants with dysarthria, and 20 control participants. None of the control voices were rated as exhibiting any of the six parameters described by the GIRBAS, while 7 of the CT participants were noted to have at least a mild voice disorder. Roughness, instability, breathiness and asthenicity were all identified as voice characteristics in the CT voice samples. Acoustically, the CT voice samples differed significantly from the controls' voices on frequency and amplitude perturbation measures. Our findings confirmed voice dysfunction as a component of dysarthria in children treated for cerebellar tumour, and discussed the links between acoustic and perceptual descriptions.

Adolescent↗
PubMedDate not supplied

Matching the neural adaptation in the rat ventral cochlear nucleus produced by artificial (electric) and acoustic stimulation of the cochlea.

To investigate neural adaptive properties, near-field evoked potentials were recorded from a chronically implanted electrode in the ventral cochlear nucleus in awake Long-Evans rats exposed to acoustic stimuli or receiving intracochlear electric stimulation. Stimuli were 250-ms trains of repetitive acoustic clicks (10, 30 and 50 dB SPL) or biphasic electric pulses (30, 50 and 70 microA) with intratrain pulse rates ranging from 100 to 1000 pulses per second (pps). The amplitude of the first negative (N(1)) to positive (P(1)) component of the average evoked potentials was measured for each consecutive individual pulse in the train. While a progressive exponential decrease in N(1)-P(1) amplitude was observed as a function of the position of the pulse within the train for both types of stimulation, the decrement of electric responses (adaptive pattern) was substantially less prominent than that observed for acoustic stimuli. Based on this difference, the present work was extended by modifying electric stimuli in order to try to restore normal adaptation phenomena. The results suggest the feasibility of mimicking acoustic adaptation by stimulation with exponentially decreasing electric pulse trains, which may be clinically applicable in the auditory implant field.

Acoustic Stimulation↗
PubMed2006

Acoustic plus electric speech processing: preliminary results of a multicenter clinical trial of the Iowa/Nucleus Hybrid implant.

AIM: This communication details the latest preliminary results from an ongoing multicenter single-subject design clinical trial of the Iowa/Nucleus Hybrid 10-mm cochlear implant. Selection criteria, surgical strategies used for hearing preservation, and the benefits of preserved residual low-frequency hearing, improved word understanding in noise, and music appreciation are described. PATIENTS AND METHODS: The device has been implanted in 48 individuals with residual low-frequency hearing. RESULTS: Hearing preservation has been accomplished in 46/48 subjects. Acoustic speech perception has also been preserved. Combined acoustic plus electric speech processing has enabled most of this group of volunteers to gain improved word understanding as compared to their preoperative hearing with bilateral hearing aids. A subset of subjects with 12 months or more experience demonstrates CNC word understanding continues to improve more than 24 months after implantation. Improved word understanding in noise is also a benefit of acoustic plus electric speech processing. CONCLUSIONS: The improvement of speech in noise and melody recognition is linked to the ability to distinguish fine pitch differences as the result of preserved residual low-frequency acoustic hearing. Both of these measures are very important in real life to the hearing impaired. Preservation of residual low-frequency hearing should be considered when expanding candidate selection criteria for standard cochlear implants.

Acoustic Stimulation↗
PubMed1986

Factors influencing the evolution of acoustic communication: biological constraints.

Numerous studies have investigated selective forces that appear to influence the evolution of acoustic communication systems. I review a number of constraints on evolution in these systems. A species' history is of undeniable importance in the analysis of any trait. However, studies have given little or no attention to phylogenetic patterns of acoustic signals. This precludes the identification of phylogenetic constraints, and should be viewed as a serious constraint on our ability to understand how communication systems evolve. Morphological constraints influence the energetic efficiency of acoustic communication. To maximize transmission distance of signals used in long-range communication, the animal's morphology favors signals with high frequencies. Thus morphology acts in opposition to properties of the environment, which favor low frequencies for use in long-range communication. Sensory receptors also play an important role in the evolution of acoustic signals. There is significant variation in the frequency range to which an inner-ear organ of the frog is sensitive. Different lineages of frogs are characterized by ear organs with different ranges of sensitivity. This variation should influence the frequency range over which calls evolved and, as a consequence, might have influenced the rate at which different lineages of anurans speciate.

Acoustics↗
PubMed1991

The representation of stop consonants in three-dimensional acoustic space.

An acoustic study of English initial voiced stops showed that the three place categories are well distinguished on the basis of three properties: second-formant onset frequency (F2 onset), second-formant frequency of the vowel nucleus (F2), and third-formant onset frequency (F3 onset). Ten male and 10 female subjects produced multiple tokens of /bVt/, /dVt/, and /gVt/ with ten different medial vowels. Three-dimensional scatterplots were generated using the above acoustic properties as coordinates. Three nonoverlapping clusters corresponding to the three place categories were evident across all subjects. Discriminant analyses based on F2 onset, F2 vowel, and F3 onset as predictor variables showed a mean correct categorization rate of 84.5% when tested within gender groups. The graphic and statistical results are interpreted as indicating that phonetic categories may be defined and represented in purely acoustic terms if variably valued multiple acoustic properties are relationally examined.

Adolescent↗
PubMed1999

Tissue characterization of myocardial cells by use of high-frequency acoustic microscopy: differential myocyte sound speed and its transmural variation in normal, pressure-overload hypertrophic, and amyloid myocardium.

The purpose of the present study was to evaluate the acoustic properties of myocytes in normal, pressure-overload hypertrophic, and amyloid myocardium. Myocardial tissue specimens at autopsy were obtained from 10 subjects without cardiovascular disease, six patients with left ventricular (LV) hypertrophy, and six patients with cardiac amyloidosis. Sound speed of myocytes was measured at subendocardial and subepicardial regions in myocardium by use of a high-frequency (450 MHz) acoustic microscope. In normal myocardium, the sound speed of myocytes was significantly higher in subendocardial region (1,728+/-19 m/sec) than in subepicardial region (1,645+/-22 m/sec) (p<0.0001). A significantly higher sound speed of myocytes was observed in the subendocardial region in LV hypertrophic myocardium (1,779+/-19 m/sec) than that in normal myocardium (p<0.001). In amyloid myocardium, a significantly lower sound speed of myocytes was observed in subendocardial (1,560+/-8 m/sec) and subepicardial (1,594+/-48 m/sec) regions than that in respective regions of the normal myocardium (p<0.0001 and p<0.05, respectively). Transmural variation in sound speed of myocytes measured by high-frequency acoustic microscopy existed in normal left ventricle. The differential myocyte sound speed and its transmural variation was observed in LV hypertrophic and amyloid myocardium as compared with normal myocardium. High-frequency acoustic microscopy can be a promising technique for myocardial tissue characterization at the myocyte level.

Acoustics↗
PubMed2002

Acoustic signature of the normal swallow: characterization by age, gender, and bolus volume.

Despite growing clinical use, cervical auscultation suffers from a lack of research-based data. One of the strongest criticisms of cervical auscultation is that there has been little research to demonstrate how dysphagic swallowing sounds are different from normal swallowing sounds. In order to answer this question, however, one first needs to document the acoustic characteristics of "normal," nondysphagic swallowing sounds. This article provides the first normative database of normal swallowing sounds for the adult population. The current investigation documents the acoustic characteristics of normal swallowing sounds for individuals from 18 to more than 60 years of age over a range of thin liquid volumes. Previous research has shown the normal swallow to be a dynamic event. The normal swallow is sensitive to aging of the oropharyngeal system, and also to the volume of bolus swallowed. The current investigation found that the acoustic signals generated during swallowing were sensitive to an individual's age and to the volume of the bolus swallowed. There were also some gender-specific differences in the acoustic profile of the swallowing sound. It is anticipated that the results will provide a catalyst for further research into cervical auscultation.

Acoustics↗
PubMed2005

Acoustic rhinometry: accuracy and ability to detect changes in passage area at different locations in the nasal cavity.

OBJECTIVES: To evaluate the accuracy of acoustic rhinometry (AR) measurements, and to assess how well AR detects obstructions of various sizes at specific sites in the nasal cavity, we created a cast model from an adult cadaver nasal cavity. METHODS: The actual cross-sectional areas of the cast model nasal passage were determined by computed tomography and compared with the corresponding areas measured by AR. To assess how nasal obstruction affects the AR results, we placed small wax spheres of different diameters at specific sites in the model (nasal valve, head of the inferior turbinate, head of the middle turbinate, middle of the middle turbinate, choana, and nasopharynx). RESULTS: The AR-derived cross-sectional areas in the first 6.5 cm of the cast model nasal cavity were very close to the corresponding areas calculated from computed tomographic sections perpendicular to the presumed acoustic axis. However, AR overestimated the passage areas at locations posterior to the 6.5-cm point. Acoustic rhinometry gave an accurate indication of the passage area of the nasal valve and its distance from the nostril. The nasal valve and the choana were indicated by significant dips on the AR area-distance curve, whereas the curve was smooth throughout the region that included the head of the inferior turbinate, the head of the middle turbinate, the middle of the middle turbinate, and the nasopharynx. In other words, AR did not discretely identify these latter sites. Acoustic rhinometry detected the different-sized inserts (obstructions) more accurately at the nasal valve than at sites posterior to this location. CONCLUSIONS: The results of the study show that AR is a valuable method for assessing the anterior nasal cavity. This technique is sensitive for detecting changes in passage area at the nasal valve region; however, the sensitivity is lower at sites posterior to this. The findings suggest that when there is substantial narrowing of the nasal valve, AR will not identify an obstruction at any location posterior to the nasal valve. In such situations, AR measurements beyond the abnormal nasal valve may easily lead to misinterpretation of the patient's nasal anatomy or condition.

Cross-Sectional Studies↗
PubMedDate not supplied

Efficacy of acoustic reflectometry in detecting middle ear effusion.

The acoustic otoscope measures the amount of sound reflected from the tympanic membrane. Since the amount of reflected sound is increased by fluid in the middle ear, it seemed likely that the acoustic otoscope could be used for detection of otitis media. We compared acoustic reflectometry with over 4,000 tympanometric and otoscopic examinations in 451 children who were examined at regular intervals following surgery for chronic otitis media with effusion. The data indicate a lower sensitivity and specificity of acoustic reflectometry than had been reported previously. The receiver-operator characteristics of this device are discussed.

Acoustic Impedance Tests↗
PubMed1989

Clinical applications of evoked acoustic emissions: results in normally hearing and hearing-impaired subjects.

Click-evoked otoacoustic emissions were recorded in a group of normally hearing subjects (n = 52 ears) and a group of patients demonstrating several common types of sensorineural hearing loss (n = 85 ears) in order to study the clinical applicability of acoustic emissions. In the normally hearing population, all ears demonstrated acoustic emissions that could be elicited at intensities below the normal subjective threshold for the sequence of clicks (mean, -5.2 dB hearing level [HL]). Sixty-seven percent of the normal ears showed long (greater than 20 ms) click-evoked emissions, and spectral analysis showed a broadband spectral component with several narrowband frequency peaks. In patients with sensorineural hearing loss, the incidence of acoustic emissions decreased and the detection threshold increased linearly with increasing threshold. No emissions were elicited from ears exhibiting subjective click thresholds greater than 35 dB HL. Hearing-impaired ears showed a significantly higher proportion of short duration emissions and a significant reduction in the mean number of narrowband frequency peaks in comparison to the controls. Therefore, acoustic emissions can be used as a reliable technique for objective study of normal micromechanical activity within the cochlea and for detection of subtle changes in cochlear disease. However, they have not been demonstrated to be useful in differentiating cochlear disease.

Acoustic Stimulation↗
PubMed1992

Recovery from repeated sudden hearing loss with corticosteroid use in the presence of an acoustic neuroma.

Sensorineural hearing loss of sudden onset may be the presenting symptom in up to 14% of patients with acoustic neuroma. We present the first reported case of sudden hearing loss in an only hearing ear with recovery to normal levels after steroid therapy on four separate occasions. Evaluation revealed a 1.5-cm acoustic neuroma. After middle cranial fossa decompression, a fifth episode with recovery after steroid use was documented. A review of the recent literature is presented, emphasizing the possible causation of sudden sensorineural hearing loss with recovery to normal in patients with acoustic neuroma. Modalities of therapy for the dilemma of the acoustic neuroma in an only hearing ear are discussed, including surgery, radiotherapy, and chemotherapy. An aggressive approach to the evaluation of the cause of sudden hearing loss is suggested.

Audiometry, Pure-Tone↗
PubMedDate not supplied

Perceptual and acoustic evidence for reduced fluency in the vicinity of stuttering episodes.

A perceptual experiment and acoustic analyses were conducted to address the question whether stuttering occurs only at specific "moments" or whether it also affects the surrounding speech. Sections of stutterers' speech were extracted from clauses which were spoken completely fluently (control) or contained one stutter (experimental). In the experimental sections, only speech up to or following the stuttered word was employed. All sections were rated by independent groups of subjects for fluency, the nature of the excised stutter (repetition or prolongation), and the temporal position of the stutter relative to the fluent section that they heard (before or after). Two additional groups of listeners were asked to select from experimental-control pairs the section that had been drawn from near a stutter, and to indicate type and position of the stutter. Listeners could reliably judge which sections had been near a stutter and the type of that stutter, but not its position. Acoustic analyses showed that there were no differences in duration, rate, number of pauses, and average intensity between the experimental and control sections. However, there were significant differences in terms of the drop in intensity between the syllables in the respective sections. The perceptual identification of experimental versus control sections showed a significant relationship with this acoustic measure and with speech rate. The judgments about the type of stutter only correlated with drop in intensity. We conclude that stuttering episodes affect the intensity-time profile of the speech in their vicinity, and that listeners can use this acoustic information to infer the presence and type of the stutter.

Humans↗
PubMed1985

Acoustic tumors: preoperative measurement and correlation with postoperative facial nerve function.

The cases of 67 patients consecutively operated on for acoustic tumors are reported. Preoperative records consist of tumor size and the position of the fourth ventricle on computerized tomography (CT) scans. An analysis is made of the immediate postoperative and current function of the facial nerves. There is a statistically significant relationship between the number of weak or paralyzed seventh nerves and displacement of the fourth ventricle (P less than .05). It is now possible to accurately measure acoustic tumors on preoperative CT scans. The position of the fourth ventricle can also be clearly seen. The current standard of diagnosis and management of acoustic tumors should include a cursor measurement of tumor size on CT scan and a notation of the position of the fourth ventricle. Adoption of this method of reporting will permit meaningful evaluation of treatment for acoustic tumors. This analysis illustrates the importance of accurate measurements in reporting and evaluating surgical results.

Facial Nerve↗
PubMed1986

Acoustic neuroma presenting as sudden hearing loss with recovery.

In our series of patients operated on for acoustic neuromas at New York University Medical Center between 1974 and 1983, 13% (17 of 133) had sudden hearing loss. Of these, approximately 23% (four of 17) had recovered auditory function before acoustic neuroma extirpation. Three patients spontaneously recovered, while one improved with steroid therapy. Contrast computerized tomography demonstrated a widened internal auditory canal and evidence of cerebellopontine angle tumor, respectively, in 88% and 59% of patients with sudden hearing loss and acoustic neuroma. Clinical characteristics suggesting acoustic neuroma as the cause of sudden hearing loss with or without auditory recovery could not be identified in our series. Our data support the rationale that patients with unilateral sudden hearing loss, even with recovery, must be evaluated for a possible cerebellopontine lesion.

Adolescent↗