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PubMed2002

Objective measurement of nasal airway dimensions using acoustic rhinometry: methodological and clinical aspects.

INTRODUCTION: Nasal congestion is an important symptom in many diseases of the upper airways. Nasal congestion may also affect personal well-being and quality of life. Furthermore, as the nasal mucosa is the first part of the airways in contact with the environment, objective evaluation of nasal congestion or nasal patency is important. Systematic evaluation of nasal patency was described in the last part of the 19th century by Zwaardemaker. Measurement of the pressure drop over the nasal cavity at a passive dow has been described in 1903 by Courtade and is one of first descriptions rhinomanometry. The technique is still in use and computer technology has made the measurements much easier but the method has not yet been accepted for wide clinical use. METHODOLOGY: Acoustic methods have also been used for evaluation of nasal patency. A qualitative method was the hum-test by Spiess (1902), where external occlusion of the nonocciuded side of the nasal cavity is experienced as a change in the timbre of the sound during humming. Acoustic reflections have been used in geophysical investigations especially with regard to search for oil. The use of acoustic reflections from the airways gained special interest in 1960-70 for determining the geometry of the vocal tract shape with regard to speech reconstruction. A method described by A. Jackson (1977) was adopted and for the first time applied to the nasal cavity. The method for determining the cross-sectional area as function of distance in the airways by acoustic reflections is impulse or relatively simple. The incident sound pseudorandom noise in the audible frequency range is compared with the response - the reflections from the airways. Intuitively, if the size of the entrance to the airways is known, the size of the reflections may represent changes of the airway size and the time between reflections may give the distance between the changes, dependent on the speed of sound. In this way it is possible to determine the area as function of distance in the airways. The technique has some assumptions and the major effort has been to validate use in the nose and elucidate aspects with regard to sound loss in the airways and resolution. Therefore, the acoustic reflection technique - named acoustic rhinometry - was compared with other methods like MRI, CT, and rhinomanometry. Allergic and nonallergic subjects were also compared. RESULTS: Acoustic rhinometry showed reasonable correlation with CT in a cadaver and in 10 subjects in comparison with MRI for the first 6 cm of the nasal cavity. Models based on MRI scannings of subjects also showed good correlation for the first 6 cm of the nasal cavity. Posteriorly in the nasal cavity and the epipharynx, differences were found mainly due to 'sound loss' to the paranasal sinuses. Sound loss due to viscous loss or friction at increasing surface/area ratio (the complex geometry in the nose) and loss due to nonrigidity the nasal mucosa were also examined. Neither these factors affected the area-distance function significantly. Acoustic rhinometry seems to reflect the area-distance function in the nose reasonably accurately. In allergic subjects acoustic rhinometry has been used to evaluate hypersensitivity. More pronounced spontaneous variation in nasal mucosa congestion was found in patients suffering from hay fever compared to nonallergic subjects. Furthermore, a tendency to a more swollen mucosa in the allergic subjects compared to the normal state, and increased sensitivity to histamine was found. This and reduction in swelling of the mucosa in allergic subjects during nasal steroid treatment out of the pollen season indicate an ongoing inflammatory process or hypersensitivity in allergic subjects out ot the pollen season. During allergen challenge the change in nasal cavity dimension as well as inflammation may affect olfaction in hay fever patients. DISCUSSION: Acoustic rhinometry has not only been used to examine hay fever patients but in many different aspects of rhinology. Since the introduction of the acoustic reflection technique in the nose more than papers using the technique have been published. Most of the papers find the technique valuable for evaluation of nasal patency. Fortunately, some critical papers have drawn attention to some practical aspects of the technique. Standard operating procedures, and calibration checks as well as training operators will enhance the accuracy and reproducibility of results. CONCLUSION AND PERSPECTIVES: A decade after its introduction acoustic rhinometry is a well-established method for evaluation of nasal patency, but further improvement can be obtained by continued validation and adjustments of the technique.

Animals↗
PubMed2003

Value of acoustic rhinometry for measuring nasal valve area.

OBJECTIVE: To assess the validity of acoustic rhinometry for measuring nasal valve area in human subjects. STUDY DESIGN: A comprehensive study that compared acoustic rhinometry data with computed tomography findings from scans obtained perpendicular to the acoustic axis and perpendicular to the floor of the nose. METHODS: Fifty nasal passages of 25 healthy adults with no nasal disease were examined by acoustic rhinometry and computed tomography. In each case, the area of the nasal valve as measured by acoustic rhinometry was compared with the area calculations from computed tomography sections taken in two different coronal planes, one perpendicular to the acoustic axis and one perpendicular to the floor of the nose. Computed tomography slices perpendicular to the floor of the nose were obtained at two different locations, a specific distance from the tip of the nose and a specific distance from the anterior nasal spine. RESULTS: There was a significant correlation between the nasal valve areas determined by acoustic rhinometry and computed tomography when imaging was obtained perpendicular to the acoustic axis. In contrast, when scanning was obtained perpendicular to the straight axis of the floor of the nose, the correlations between the acoustic rhinometry and computed tomography data were weak. CONCLUSIONS: When any type of imaging is used for comparison with nasal valve areas determined by acoustic rhinometry, the cross-sections should be perpendicular to the acoustic pathway. The results of the study show that acoustic rhinometry is a valuable method for measuring nasal valve area.

Adult↗
PubMed1994

Relation between local acoustic parameters and protein distribution in human and porcine eye lenses.

The purpose of this study is to characterize the eye lens (human, porcine) by acoustic measurements and to investigate whether relations exist with the local protein content. The acoustic measurements were performed with a 'scanning acoustic microscope' (SAM), operating at a frequency of 20 MHz. At this frequency the lateral resolution in the acoustic images was 150 microns. A double-transmission pulse-echo technique was employed to obtain acoustic parameter images of a central, 1-mm-thick slice of the lenses. The two-dimensional images were derived by ultrasonic spectroscopy displaying the ultrasound velocity, the attenuation at 20 MHz and the slope of the attenuation coefficient between 17 and 23 MHz. The images were summarized by profiles along the optical and equatorial axes of these parameters. Acoustic parameters were obtained from human lenses (n = 13) and porcine lenses (n = 10). The protein contents of human lenses were obtained from literature. Additionally, Raman microspectroscopy was used to measure the local protein content of porcine lenses (n = 3). Profiles along the optical and equatorial axes were obtained. The relation between the protein content and the acoustic parameters was obtained qualitatively by comparison of the shape of the profiles and, where possible, quantitatively by calculating the Pearson correlation coefficients. Furthermore, the results have been related to a statistical metastudy found in literature in which the relation between collagen, protein and acoustic velocity in various biological tissues was investigated. The results show a gradual decrease of the magnitude of the acoustic parameters from the centre to the periphery of the porcine eye lens, which is clearly equivalent to the decrease in profiles of the protein content. For the human lenses the acoustic characteristics and the protein content exhibit the same profile, fairly constant in the lens nucleus and decreasing towards the periphery of the lens cortex. Strong positive correlation coefficients for acoustic parameters and protein content for the porcine lens are found. It is concluded that protein concentration related phenomena can be investigated by measuring the acoustic parameters.

Adult↗
PubMed2005

Acoustic streaming in ovarian cysts.

OBJECTIVE: The purpose of this study was to investigate the hypothesis that endometriomas do not show acoustic streaming and then to quantify the streaming velocity of the particles within ovarian cysts that do show acoustic streaming. METHODS: Ovarian cysts greater than 2 cm in diameter, with internal echoes seen on B-mode sonography, were prospectively evaluated for the presence of acoustic streaming. If acoustic streaming was present, a 2-mm pulsed Doppler sample volume was then placed within the distal portion of the cyst, and the streaming velocity was recorded. Follow-up included review of subsequent sonographic examinations, surgical notes, and histopathologic reports, with the latter being considered the final results if available. RESULTS: Acoustic streaming was detected in 10 (38%) of 26 ovarian cysts, but of the 10 endometriomas, none (0%) showed acoustic streaming (P = .002). Acoustic streaming was detected in 86% (n = 6) of cystadenomas. Four of these were serous cystadenomas, which all showed acoustic streaming, with a velocity range of 1.5 to 3.6 cm/s. Two mucinous cystadenomas showed acoustic streaming with velocities of 0.8 and 2.0 cm/s. CONCLUSIONS: Endometriomas appear as cysts containing homogeneous, low-level, "ground glass" echoes on gray scale sonography. Other types of ovarian cysts can also have these appearances. Endometriomas do not show acoustic streaming. Cystadenomas may have streaming velocities within a defined range. Acoustic streaming assessment may therefore prove to be an additional useful tool in assessing ovarian cysts and in completely excluding endometrioma as a diagnosis if a cyst shows acoustic streaming.

Adolescent↗
PubMed2003

Measurement of acoustical characteristics of mosques in Saudi Arabia.

The study of mosque acoustics, with regard to acoustical characteristics, sound quality for speech intelligibility, and other applicable acoustic criteria, has been largely neglected. In this study a background as to why mosques are designed as they are and how mosque design is influenced by worship considerations is given. In the study the acoustical characteristics of typically constructed contemporary mosques in Saudi Arabia have been investigated, employing a well-known impulse response. Extensive field measurements were taken in 21 representative mosques of different sizes and architectural features in order to characterize their acoustical quality and to identify the impact of air conditioning, ceiling fans, and sound reinforcement systems on their acoustics. Objective room-acoustic indicators such as reverberation time (RT) and clarity (C50) were measured. Background noise (BN) was assessed with and without the operation of air conditioning and fans. The speech transmission index (STI) was also evaluated with and without the operation of existing sound reinforcement systems. The existence of acoustical deficiencies was confirmed and quantified. The study, in addition to describing mosque acoustics, compares design goals to results obtained in practice and suggests acoustical target values for mosque design. The results show that acoustical quality in the investigated mosques deviates from optimum conditions when unoccupied, but is much better in the occupied condition.

Acoustics↗
PubMed2006

Contribution of low-frequency acoustic information to Chinese speech recognition in cochlear implant simulations.

Chinese sentence recognition strongly relates to the reception of tonal information. For cochlear implant (CI) users with residual acoustic hearing, tonal information may be enhanced by restoring low-frequency acoustic cues in the nonimplanted ear. The present study investigated the contribution of low-frequency acoustic information to Chinese speech recognition in Mandarin-speaking normal-hearing subjects listening to acoustic simulations of bilaterally combined electric and acoustic hearing. Subjects listened to a 6-channel CI simulation in one ear and low-pass filtered speech in the other ear. Chinese tone, phoneme, and sentence recognition were measured in steady-state, speech-shaped noise, as a function of the cutoff frequency for low-pass filtered speech. Results showed that low-frequency acoustic information below 500 Hz contributed most strongly to tone recognition, while low-frequency acoustic information above 500 Hz contributed most strongly to phoneme recognition. For Chinese sentences, speech reception thresholds (SRTs) improved with increasing amounts of low-frequency acoustic information, and significantly improved when low-frequency acoustic information above 500 Hz was preserved. SRTs were not significantly affected by the degree of spectral overlap between the CI simulation and low-pass filtered speech. These results suggest that, for CI patients with residual acoustic hearing, preserving low-frequency acoustic information can improve Chinese speech recognition in noise.

Acoustic Stimulation↗
PubMed2000

Auditory brainstem response and magnetic resonance imaging for acoustic neuromas: costs by prevalence.

OBJECTIVE: To compare hypothetical costs for identification of acoustic tumors when using magnetic resonance imaging with gadolinium Gd 64 (MRI-(64)Gd) as a sole diagnostic test and when using auditory brainstem response (ABR) testing followed by MRI-( 64)Gd (ABR + MRI-(64)Gd) for those with positive ABR findings. PATIENTS AND METHODS: Retrospective review of the medical records of 75 patients having surgically confirmed acoustic neuromas to categorize them into 3 subgroups relative to their risk of having a cerebellopontine angle tumor based on history, symptoms, and routine pure-tone and speech audiometric findings. Hypothetical costs associated with identification of patients with acoustic neuroma in each subgroup were calculated for MRI-(64)Gd alone and ABR + MRI-( 64)Gd. Auditory brainstem response sensitivity and specificity data for the 75 patients with acoustic neuroma and 75 patients without a tumor matched for hearing loss were applied to the hypothetical subgroups. Tumor size was considered also. SETTING: Tertiary care center. MAIN OUTCOME MEASURE: Comparison of costs for MRI-(64)Gd and ABR + MRI-(64)Gd. RESULTS: Fouteen patients with acoustic neuroma were assigned to the high-risk category (30% probability); 45 were in the intermediate-risk category (5% probability); and 16 were in the low-risk category (1% probability). Auditory brainstem response testing correctly identified 100% of the large tumors (>2.0 cm), 93% of the medium-sized tumors (1.1-2.0 cm), and 82% of the small tumors (<1.0 cm). The hypothetical costs for identifying 14 patients with acoustic neuroma among 47 patients in the high-risk category using MRI-(64)Gd would be $70,500; ABR + MRI-(64)Gd costs for the 13 patients identified by ABR would be $39,600. Hypothetically 900 patients would be tested to identify the 45 acoustic neuromas in the intermediate-risk category. Magnetic resonance imaging with (64)Gd screening would reach $1.35 million for this sample. Auditory brainstem response testing and MRI-(64)Gd would be $486,000, but 4 acoustic neuromas would be missed. For the low-risk subgroup MRI-6(4)Gd screening of 1600 patients to identify 16 acoustic neuromas would total $2.4 million; ABR + MRI-(64)Gd to identify 15 of them would be $787,500. In this sample of 75 acoustic neuromas, large tumors were more prevalent in the low-risk subgroup than in the high- or intermediate-risk subgroups. CONCLUSIONS: Decisions regarding assessment of patients at risk for acoustic neuromas must be made on a case-by-case basis. Use of ABR + MRI-( 64)Gd allows considerable savings when patients are in the intermediate- or low-risk subgroups. New MRI and ABR testing techniques offer promise for reducing costs.

Cerebellar Neoplasms↗
PubMed1997

Nasal cavity geometry measured by acoustic rhinometry and computed tomography.

OBJECTIVE: To determine the significance of cross-sectional areas obtained by acoustic rhinometry. DESIGN: Comparison of data obtained by acoustic rhinometry and computed tomography (CT). SETTING: Outpatient clinic. PATIENTS: Nine adults with nasal obstruction due to turbinate hypertrophy. MAIN OUTCOME MEASURES: Acoustic rhinometry and CT were performed after nasal decongestion. The acoustic area-distance curve was analyzed based on 3 notches (A1, A2, and A3) corresponding to 3 local minimal areas. Computed tomographic measurements were made in the coronal plane at 0.5-cm intervals, and the narrowest sections in the anterior (S1), middle (S2), and posterior (S3) parts of the nasal cavity were selected. Mean specific section areas and volumes were computed by integration of the acoustic area-distance curves using the same procedure for the 2 methods. RESULTS: Significant correlations were found between acoustic and CT areas in the anterior nasal cavity (A1 vs S1, P < .001; A2 vs S2, P < .005). Acoustic and CT anterior volumes from A1 to A2 and from S1 to S2 were significantly correlated with each other (P < .005). No correlation was found between acoustic and CT areas measured at the posterior part of the nose (A3 vs S3). A weak correlation was evidenced between acoustic and CT posterior volumes from A2 to A3 and from S2 to S3 (P < .05). CONCLUSIONS: Acoustic rhinometry may be particularly well suited to the evaluation of anterior nasal geometry during clinical studies. At the posterior part of the nose, acoustic measurements may be of limited clinical relevance.

Acoustics↗
PubMed1998

Acoustical modulation of electrically evoked otoacoustic emission in intact gerbil cochlea.

In order to study the interaction between mechanical-electrical and electrical-mechanical transductions of outer hair cells (OHCs) in vivo, we observed the acoustically induced changes in the electrically evoked otoacoustic emission (EEOAE). One pole of a bipolar electrode was placed in the round window niche and the other pole on the surface of the first cochlear turn in the gerbil. A microphone and a speaker were used to monitor the EEOAE and to deliver an acoustical tone, respectively. It was found that a high sound level acoustical tone enhanced the EEOAE fine structure at frequencies below the acoustical frequency, and suppressed the overall level of the EEOAE at frequencies above the acoustical frequency. In addition, the EEOAE at frequencies approximately one half octave lower than the acoustical frequencies were relatively more enhanced or showed relatively less suppression than at other frequencies. The amplitudes of these changes had a positive relationship with acoustical tone levels. Furosemide eliminated the acoustically caused EEOAE change indicating that the acoustically caused change in the EEOAE is a phenomenon of the normal cochlea. One possible mechanism for the results is that the electrically and acoustically evoked basilar membrane (BM) vibrations interact at the EEOAE generation site and change the local mechanical and electrical properties. The second possible mechanism is that the acoustical stimulus creates an impedance discontinuity at its characteristic frequency location leading to a change in the reflected electrically evoked traveling wave, which may enhance or suppress the EEOAE by the vector summation of two waves.

Acoustic Stimulation↗
PubMed1978

Functional characteristics of cochlear nucleus in behaving cat examined by acoustic masking of electrical stimuli.

1. Cats were trained, using an operant procedure, to detect and respond to electrical stimulation delivered in the vicinity of the cochlear nucleus. The electrical stimuli were presented both in silence and in synchrony with repeated noise bursts to determine whether detection thresholds for the electrical stimuli were elevated by the acoustic masking noise. 2. For stimulation sites centered within auditory structures (cochlear nucleus or acoustic nerve root), the acoustic maskers caused a consistent elevation of the electrical detection thresholds. For stimulation sites that were in or bordered on nonacoustic neural structures (e.g., vestibular), the acoustic maskers caused little or no elevation of electrical detection thresholds. 3. The magnitude of the acoustic masking effect was monotonically related to the intensity of the acoustic masker across the range of intensities tested. 4. The magnitude of the masking effect was strongly dependent on the relative timing of the stimulus pulse and the masker noise burst. Maximum masking occurred when the pulse just followed the onset of the neural activity in cochlear nucleus evoked by the masker burst. Less masking occurred when the electrical pulse occurred at the middle or end of the masker burst, and still less when the pulse occurred just prior to the onset (backward masking) or just after the offset (forward masking) of the masker burst. 5. The magnitude of the masking effect also depended on the frequency of the acoustic masker. For tone bursts, masking was maximal for each electrode at a particular frequency and declined monotonically for masker frequencies above or below the optimal frequency. 6. It is concluded that the masking of an electrical stimulus by an acoustic stimulus depends on a direct interaction between the neural responses evoked by the two stimuli, and that similar central, neural interactions may contribute to acoustic masking of acoustic stimuli. It is also concluded that the technique of masking an electrical stimulus by an acoustical stimulus is a precise and useful tool for the study of sensory-neural organization in intact behaving animals.

Animals↗
PubMed1985

Acoustic-reflex dynamics and the loudness-discomfort level.

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.

Acoustic Stimulation↗
PubMed1991

Dissociation of tactile and acoustic components in air puff startle.

Tactile (air puff) or acoustic startle stimuli elicit behavioral (motor) and complex cardiovascular responses which include pressor as well as cardiac decelerative and accelerative responses. An acoustic component of the air puff stimulus (12.5 psi) was identified. Studies were conducted to separate the contributions of both stimulus modalities to the observed responses. The acoustic component was approximated with a wide-spectrum 97-dB white-noise stimulus. This acoustic stimulus failed to evoke heart rate responses but did yield motor and pressor responses. In a second approach, tympanic membrane rupture (TMR) was used to interrupt acoustic sensory stimuli. TMR fully abolished the motor and pressor responses to acoustic startle. With air puff startle, while TMR severely attenuated the motor response it only decreased slightly the pressor and cardiac accelerative responses and failed to influence the cardiac decelerative component. Our results indicate that air puff startle contains both tactile and acoustic modalities. Further, the motor response is largely driven by the acoustic modality since TMR abolished this response elicited by either acoustic or tactile stimulation. More importantly, motor and cardiovascular responses to startle may be separated through discrimination of afferent stimuli suggesting either differences in neural pathways for acoustic and tactile stimuli or a differential dependency of the various responses on stimulus characteristics.

Acoustic Stimulation↗
PubMed1997

A randomized controlled trial of a new fetal acoustic stimulation test for fetal well-being.

OBJECTIVES: Our purpose was to determine (1) whether a fetal acoustic stimulation test results in more palpable fetal movement compared with a mock test (control) and (2) whether palpated fetal movements after a fetal acoustic stimulation test are accompanied by a reactive nonstress test. STUDY DESIGN: In a randomized controlled trial we studied women seen in the labor and delivery suite for various indications. Women were excluded for multiple gestation, < 31 weeks' gestational age, treatment with magnesium sulfate or narcotics, or ruptured membranes. Informed consent was obtained from eligible women, who were then randomized to a test or control group. We placed an acoustic stimulator on the abdomen of each woman, but only the test group was stimulated. We assessed fetal movement by a grading system: 0 = no fetal movement felt by patient or tester, 1 = fetal movement felt by patient only, 2 = fetal movement felt by tester, 3 = visual movement seen by tester. A positive fetal acoustic stimulation test result was defined as one with any fetal movement felt or seen by the tester (grades 2 or 3). We then performed a nonstress test. We compared rates of a positive fetal acoustic stimulation test in the test and control groups with the chi 2 test. A p value < 0.05 was considered significant. RESULTS: We randomized 297 women to the test group and 280 women to the control (mock test) group. Of women tested with the fetal acoustic stimulation test. 81% had fetal movement by palpation or visualization (grades 2 or 3) compared with 19% of the control group (p < 0.0001, odds ratio 19.29, 95% confidence interval 12.42 to 30.07). Of the test group, 283 (95%) had a reactive nonstress test and 14 (5%) had nonreactive tests; the control group had 267 (95%) reactive and 13 (5%) nonreactive nonstress tests. Of 242 patients in the test group with a positive fetal acoustic stimulation test, 236 (98%) had a reactive nonstress test. Of those in the test group with fewer than three contractions per 10 minutes. 164 (89%) had a positive fetal acoustic stimulation test. Of these, 162 (99%) had a reactive nonstress test. CONCLUSION: The fetal acoustic stimulation test evokes significantly more palpated or visualized fetal movement than in controls. Palpated or visualized fetal movement after acoustic stimulation was almost always accompanied by a reactive nonstress test.

Acoustic Stimulation↗
PubMed2004

Validity and reliability of acoustic analysis of respiratory sounds in infants.

OBJECTIVE: To investigate the validity and reliability of computerised acoustic analysis in the detection of abnormal respiratory noises in infants. METHODS: Blinded, prospective comparison of acoustic analysis with stethoscope examination. Validity and reliability of acoustic analysis were assessed by calculating the degree of observer agreement using the kappa statistic with 95% confidence intervals (CI). RESULTS: 102 infants under 18 months were recruited. Convergent validity for agreement between stethoscope examination and acoustic analysis was poor for wheeze (kappa = 0.07 (95% CI, -0.13 to 0.26)) and rattles (kappa = 0.11 (-0.05 to 0.27)) and fair for crackles (kappa = 0.36 (0.18 to 0.54)). Both the stethoscope and acoustic analysis distinguished well between sounds (discriminant validity). Agreement between observers for the presence of wheeze was poor for both stethoscope examination and acoustic analysis. Agreement for rattles was moderate for the stethoscope but poor for acoustic analysis. Agreement for crackles was moderate using both techniques. Within-observer reliability for all sounds using acoustic analysis was moderate to good. CONCLUSIONS: The stethoscope is unreliable for assessing respiratory sounds in infants. This has important implications for its use as a diagnostic tool for lung disorders in infants, and confirms that it cannot be used as a gold standard. Because of the unreliability of the stethoscope, the validity of acoustic analysis could not be demonstrated, although it could discriminate between sounds well and showed good within-observer reliability. For acoustic analysis, targeted training and the development of computerised pattern recognition systems may improve reliability so that it can be used in clinical practice.

Acoustics↗
PubMed2004

Protection against acoustic trauma by forward and backward sound conditioning.

The purpose of the present study was to determine if short-term sound conditioning provides protection when delivered either before (forward sound conditioning) or after (backward sound conditioning) a traumatic exposure in the guinea pig. Two different sound conditioning paradigms were studied (1 kHz, 81 dB SPL, 24 h; 6.3 kHz, 78 dB SPL, 24 h). The 1-kHz forward sound conditioning paradigm (81 dB SPL, 24 h) protected distortion product otoacoustic emissions (DPOAEs) against a short-duration acoustic trauma (2.7 kHz, 103 dB SPL, 5 min) compared to the group exposed to the acoustic trauma alone. The 1-kHz forward sound conditioning paradigm (81 dB SPL, 24 h) also protected both the auditory brainstem response (ABR) thresholds and DPOAEs against a longer-duration acoustic trauma (2.7 kHz, 103 dB SPL, 30 min). The group exposed to the acoustic trauma alone showed ABR threshold shifts between 15 and 24 dB, and DPOAE amplitude shifts between 11 and 24 dB, while the group with 1-kHz forward sound conditioning showed statistically significant protection at all ABR frequencies and at all DPOAE frequencies. The 1-kHz backward sound conditioning paradigm protected against acoustic trauma (2.7 kHz, 103 dB SPL, 30 min). The ABR thresholds were protected at 1, 2 and 4 kHz, and DPOAEs at all frequencies (except 8 kHz) when compared to the group exposed only to the acoustic trauma. The 6.3-kHz forward sound conditioning paradigm protected against acoustic trauma (5.5 kHz, 109 dB SPL, 30 min) at 6.3, 8 and 10 kHz. The 6.3-kHz backward sound conditioning paradigm showed no protection against acoustic trauma at any DPOAE frequency. Taken together, these findings are important for understanding how the auditory system can be modulated by acoustic stimulation and highlights the importance of the acoustic environment during the recovery process of the auditory system.

Acoustic Stimulation↗
PubMed2001

[Acoustic analysis in patients with trauma to unilateral cricoarytenoid joint by computer technique].

OBJECTIVE: To investigate the acoustic characteristics of unilateral cricoarytenoid joint trauma and evaluate the effect of acoustic analysis technique on the diagnosis and treatment of this disease. METHOD: The voice signals of sustained vowel [a] were measured using a micro-computer with Dr. Speech software in 50 healthy adults and 30 patients with unilateral cricoarytenoid joint trauma. The acoustic parameters (jitter, shimmer and NNE) and spectrographic characteristics (harmonic waves, formants and noise) were analyzed. The acoustic changes before and after the treatment of arytenoid motion were observed and compared. RESULT: All acoustic parameters were significantly increased in trauma of unilateral cricoarytenoid joint. The pathologic spectrograph showed decrease or loss of harmonic waves and formants, and increase of noise, in middle and high frequencies. There was a relationship between NNE and the position of the vocal cord. After the treatment of arytenoid motion, 33% patients were cured and had normal acoustic parameters and spectrograph. 47% were improved with reduced parameters and improved spectrograph. The acoustics in 20% cases didn't change at all after treatment. The acoustic parameters were significantly decreased after the treatment of arytenoid motion. CONCLUSION: The present study suggested that the acoustic parameters may estimating the degrees of voice lesion as objective standards and NNE may judge the degree of glottic closure. Both acoustic parameters and spectrograph are of value in the diagnosis, treatment effect and prognosis observation to cricoarytenoid joint trauma.

Adolescent↗
PubMedDate not supplied

[Acoustic communication and sexual selection in Orthoptera (Insecta)].

Comparison of calling and courtship songs and mating strategies in different groups of Orthoptera shows that acoustic signals in bush crickets (Tettigonioidea) are used for searching conspecific mates at a distance, and song evolution is primarily driven by the acoustic surroundings and simultaneously singing other species. The role of sexual selection in the evolution of acoustic signals in bush crickets is much less important than in the evolution of other nonacoustic signals employed during direct contact. Acoustic signals of crickets (Grylloidea) are involved in both distant and short-range communication. Acoustic courtship signals, along with other courtship components, may offer the material for sexual selection, although, essentially, evolution of acoustic signals in crickets is determined by the acoustic surroundings. Acoustic communication in the grasshoppers of the subfamily Gomphocerinae is mainly a short-distance communication. Acoustic signals of Gomphocerinae are highly variable and elaborate in temporal parameters, and therefore can serve for evaluation of the mate "quality". Song evolution in this group is to a greater extent driven by sexual selection than by the acoustic surroundings and, therefore, could proceed faster than in other groups of Orthoptera and play a major role in speciation.

Acoustic Stimulation↗
PubMed2005

Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.

This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

Action Potentials↗