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At least 1,081 records · Page 60Linked to original sources
PubMed2000

Cortical mechanisms for auditory spatial illusions.

Frequency transformation by the external ears provides the spectral cues for localization of broadband sounds in the vertical plane. When human subjects listen to spectrally-impoverished narrowband sounds presented in a free field, the perceived locations vary with the centre frequency and are largely independent of the actual source locations. The present study explored the substrate of spatial illusion by examining the responses of cortical neurons to narrowband stimuli. Single-unit responses were recorded in area A2 of anaesthetized cats. Broadband noise bursts were presented at 14 locations in the vertical median plane, from 60 degrees below the front horizon, up and over the head, to 20 degrees below the rear horizon. Narrowband (1/6-oct) noise bursts were presented at + 80 degrees elevation. An artificial neural network was trained to recognize the spike patterns elicited by broadband noise and, thereby, to register the spike patterns with sound-source elevation. When the trained network was presented with neural responses elicited by narrowband noise, the elevation estimated by the neural network varied with the centre frequency of the narrowband stimuli. Consistent with psychophysical results in human, the locations associated with a given centre frequency could be predicted by comparing the stimulus spectrum with the directional transfer functions of the cat's external ear. The results support the hypothesis that full spike patterns (including spike counts and spike timing) of cortical neurons code information about sound location and that the auditory cortical neurons play a pivotal role in localization behaviour.

Acoustic Stimulation↗
PubMed2000

Aerodynamic and acoustic parameters in CO2 laser posterior transverse cordotomy for bilateral vocal fold paralysis.

The aim of this prospective study was to analyse airway improvement and acoustic and aerodynamic parameters after CO2 laser posterior transverse cordotomy (LPTC) in bilateral vocal fold paralysis (BVFP). Four patients (2 males, 2 females) were recorded pre- and post-operatively at 1, 3, 6, 12 and 24 months. Forced inspiratory volume during the first second (FIV), vital capacity, peakflow, and forced expiratory volume during the first second (FEV) were measured with the Gould II spirometer. Acoustic frequency features (average fundamental frequency, standard deviation, jitter, shimmer and harmonic-to-noise ratio) and speech duration parameters (maximum phonation time, number of words read per minute, and number of words per breath) were measured. Aerodynamic parameters were measured with the Aerophone II. Three tasks were completed. Pneumo-phonatory parameters in "maximum sustained phonation" and in "comfortable phonation", and laryngeal aerodynamic parameters (intraoral air pressure, oral airflow and sound pressure level) were measured non-invasively. Glottal resistance and vocal efficiency were calculated. FIV increased significantly after LPTC (p = 0.01). Postoperatively, frequency features were undetectable by standard commercialized algorithms. Acoustic and aerodynamic parameters improved in the measures obtained at the 6th postoperative month. These results were stable 2 years postoperatively in all cases. We conclude that laryngeal aerodynamic parameters can be used objectively to follow patients longitudinally after LPTC.

Aged↗
PubMed2001

A fractal approach to the features of speech consonants.

Fractal dimension (D) quantifies the roughness of a temporal signal and estimates its degree of freedom, allowing a good approach for its fluctuations. This present study of consonants follows the D-assessment of vowels which was presented at the Copenhagen Collegium Meeting. Using a 16 kHz time sampling the D-values of consonants were studied in the consonant-vowel context of the French language. Each consonant was pronounced four times by six males and six females. For D-measurement of long consonants the same method was used, i.e. the dyadic box-counting method and its 10 points of D-measurement (10pD) as that used for vowels. In the aim to approach infinitely small time scales, and to appreciate at least the tendency of the 10-point set, i.e. the D value to which tends this set, the slope of the three last points (3pD) was also calculated. For the plosion part of plosive consonants, a semi-continuous box-counting method devoted to the D-measurement of a short, single-dimension temporal signal was designed. This study consistently demonstrates that (i) there is a significant difference between males and females, as far as voiced and non-plosive consonants are concerned; (ii) plosive consonants are not fractal; (iii) among long consonants, D-value of fricatives are significantly different (p < 0.01), as far as 3pD measurement is considered; and (iv) in the case of nasal consonants [m] and [n], this categorization is efficient for both 3pD and 10pD measurements (p < 0.05). There results will be commented on and discussed with the aim of clinical use.

Adult↗
PubMed2004

Establishing normal hearing with the dichotic multiple-frequency auditory steady-state response compared to an auditory brainstem response protocol.

OBJECTIVE: To determine the clinical usefulness of the dichotic multiple-frequency (MF) auditory steady-state response (ASSR) technique for estimating normal hearing compared to a 0.5-kHz tone burst and broadband click auditory brainstem response (ABR) protocol in a sample of adults. MATERIAL AND METHODS: A comparative experimental research design was selected in order to compare estimations of normal hearing obtained with the dichotic ASSR technique at 0.5, 1, 2 and 4 kHz with a 0.5-kHz tone burst and broadband click ABR protocol. The recording times required for each procedure were also compared. Normal-hearing subjects (n = 28) were selected according to immittance values within normal limits and pure-tone behavioural thresholds of < 25 dB HL across frequencies. RESULTS: The dichotic MF ASSR estimated normal hearing to be, on average, 30-34 dB HL across the range 0.5-4 kHz. The mean estimate of normal hearing for 0.5 kHz using tone burst ABRs was 30 dB nHL and the mean click ABR threshold was 16 dB nHL, i.e. 14-18 dB better than the ASSR thresholds. The dichotic MFASSR technique recorded 8 thresholds (4 in each ear) in a mean time of 23 min. The ABR protocol recorded 4 thresholds (2 in each ear) in a mean time of 25 min. CONCLUSION: Both the dichotic MF ASSR and ABR protocols provided a time-efficient estimation of normal hearing. There was no significant difference between the tone burst ABR and MF ASSR techniques in terms of estimation of normal hearing at 0.5 kHz. The dichotic MF ASSR technique proved more time-efficient by determining more thresholds in a shorter time compared to the ABR protocol.

Adolescent↗
PubMed2004

A case of cortical deafness and anarthria.

Generally, cortical deafness is not complicated by anarthria and cortical anarthria does not affect auditory perception. We report a case of simultaneous progressive cortical deafness and anarthria. At the age of 70 years, the patient, a woman, noticed hearing problems when using the telephone, which worsened rapidly over the next 2 years. She was then referred to our hospital for further examinations of her hearing problems. Auditory tests revealed threshold elevation in the low and middle frequencies on pure-tone audiometry, a maximum speech discrimination of 25% and normal otoacoustic emissions and auditory brainstem, middle- and long-latency responses. An articulation test revealed abnormal pronunciation. Because of these problems only written and not verbal communication was possible; her ability to read and write was unimpaired. She showed no other neurological problems. Brain MRI demonstrated atrophic changes of the auditory cortex and Wernicke's language center and PET suggested low uptake of (18F) 2-fluoro-2-deoxy-d-glucose around the Sylvian fissures in both hemispheres. Neurologically, the patient was suspected of having progressive aphasia or frontotemporal dementia. Her cortical deafness and anarthria are believed to be early signs of this entity.

Aged↗
PubMed2006

High-speed digital imaging and electroglottography of tracheoesophageal phonation by Amatsu's method.

BACKGROUND: Our previous findings have indicated that the thyropharyngeal muscles form a retropharyngeal prominence during alaryngeal phonation via the TE fistula. This prominence forms a so-called 'neoglottis', which is thought to function as the vibratory source. To better understand the mechanism of TE phonation, we analyzed the vibration of the neoglottis using electroglottography (EGG) and a high-speed digital imaging system. PATIENTS AND METHODS: Two volunteers who use TE phonation for their daily speech communication were subjected to this study. The vibrations of the neoglottis were recorded simultaneously as EGG and high-speed imaging with acoustic signals. RESULTS: The vibrations of the neoglottis, recorded by means of high-speed digital imaging, were exactly synchronized with the waveforms of the acoustic signals and EGG. CONCLUSIONS: These results further confirm the neoglottis as the source of vibration during tracheoesophageal (TE) phonation.

Aged↗
PubMed2006

Sound-evoked myogenic potentials on the sternocleidomastoid muscle in monkeys.

CONCLUSION: We recorded sound-evoked myogenic potentials of the sternocleidomastoid (SCM) muscle using awake monkeys. The characteristics of these potentials are similar to those of vestibular evoked myogenic potentials (VEMPs) in humans, suggesting that the sound-evoked myogenic potentials of the SCM muscle in monkeys may be utilized as an animal model of VEMPs. OBJECTIVE: The pathway of the VEMPs remains uncertain as no animal model has yet been used to record sound-evoked myogenic potentials in the SCM muscle. Therefore, the present study aimed to establish an animal model of VEMPs using macaque monkeys. MATERIALS AND METHODS: Four macaque monkeys were used. A pair of electrodes was attached on the SCM muscle ipsilateral side to the intense sound stimulation. RESULTS: The sound-evoked myogenic potentials of the SCM muscle exhibited a biphasic waveform. When a click at 125 dBSPL was applied, the peak latency of the first positive wave was 12.5 ms and was not delayed when the stimulating sound intensity was reduced. The thresholds of the myogenic potentials were 103 dBSPL, which were 43 dB higher than those of the auditory brainstem response (ABR). When a short tone burst was applied, the reactive optimal frequency of the myogenic potentials was relatively low (500-1000 Hz).

Acoustic Stimulation↗
PubMed2006

Effect of deep insertion of the cochlear implant electrode array on pitch estimation and speech perception.

CONCLUSION: Deeply inserted electrodes offer the possibility that apical stimulation may improve speech performances. Therefore, deep insertion is reasonable and should be performed in patients with profound or total hearing loss. OBJECTIVES: To evaluate the importance of insertion depth beyond 25 mm in a group of cochlear implant patients with deeply inserted electrodes up to 32 mm. PATIENTS AND METHODS: In the first part of the study patients were asked to perform a pitch estimation for channels across the whole length of the electrode array. We evaluated whether pitch discrimination was possible along the whole cochlea and especially in its apical part. Then, the audiological performances of 10 patients were tested in 5 conditions, in which we artificially varied the insertion depth in each patient by activating and deactivating channels. The patients were tested immediately in the new condition to avoid adaptation. RESULTS: The results showed that activating the electrodes in the uppermost region of the cochlea improves speech perception significantly. Furthermore it could be demonstrated that the pitch perceived in the cochlea with electrical stimulation decreases with increasing insertion depth along the whole length of deeply inserted electrode arrays.

Adult↗
PubMed1998

Characteristics of the acoustic distortion product 2f2-f1 from the normal human ear.

The aim of this study was to determine the basic properties of the 2f2-f1 distortion product otoacoustic emissions (DPOEs) in 36 normally hearing subjects and to compare their characteristics with those of the 2f1-f2 DPOEs. The influence of stimulation parameters on 2f2-f1 DPOE behaviour was examined: i) stimulation levels varied from 40 to 70 dB sound pressure level in 10 dB steps; and ii) two values of the f2/f1 ratio were used (1.12 and 1.22). The prevalence and the level of the 2f2-f1 DPOEs depended on three parameters: f2 frequency, stimulation level and f2/f1 ratio. The results showed many differences between the characteristics of 2f1-f2 and 2f2-f1 DPOEs, probably due to their being generated by different mechanisms. Thus, the 2f2-f1 DPOEs may provide different information about the cochlear status and could be of clinical interest.

Acoustic Stimulation↗
PubMed1999

Speech articulation after subtotal glossectomy and reconstruction with a myocutaneous flap.

Speech samples of 9 subjects (8 males, 1 female) were recorded before and 0.5-2 years after a partial glossectomy and reconstruction with a pectoralis major myocutaneous flap. A reading sample, a list of meaningful and nonsense words, and a list of sustained vowels were recorded. The speech samples were evaluated by pairs of naive listeners and using acoustic analysis of the vowel production. Each pair listened to the recordings of only one patient. Inter-rater agreement was satisfactory. The general impression of the speech outcome varied from normal to moderately impaired. The perceptually estimated impairments of speech articulation in the after/before comparisons were statistically significant. Only the first formant of the vowel /i/ (rise) and the second formant of the vowel /a/ (drop) changed significantly at the group level. There was a negative correlation (r = -0.79) between the extent of tongue resection and the drop of the second formant of the vowel /a/. The perceptual variables showed a relationship (r = 0.74-0.82) with the changes in the level of the second formant of the vowel /i/. The relationship that emerged between the perceptual estimates and the objective acoustic parameters suggests that it will be possible to develop clinically relevant test batteries for articulatory quality analysis.

Acoustics↗
PubMed2004

Directional guidance from audible pedestrian signals for street crossing.

Typical audible pedestrian signals indicate when the pedestrian walk interval is in effect but provide little, or even misleading information for directional alignment. In three experiments, blind and blindfolded sighted adults crossed a simulated crossing with recorded traffic noise to approximate street sounds. This was done to investigate how characteristics of signal presentation affected usefulness of the auditory signal for guiding crossing behaviour. Crossing was more accurate when signals came only from the far end of the crossing rather than the typical practice of presenting signals simultaneously from both ends. Alternating the signal between ends of the crossing was not helpful. Also, the customary practice of signalling two parallel crossings at the same time drew participants somewhat toward the opposite crossing. Providing a locator tone at the end of the crossing during the pedestrian clearance interval improved crossing accuracy. These findings provide a basis for designing audible pedestrian signals to enhance directional guidance. The principal findings were the same for blind and sighted participants and applied across a range of specific signals (e.g. chirps, clicks, voices).

Accidents, Traffic↗
PubMed1993

Audibility and identification of auditory alarms in the operating room and intensive care unit.

The audibility and the identification of 23 auditory alarms in the intensive care unit (ICU) and 26 auditory alarms in the operating rooms (ORs) of a 214-bed Canadian teaching hospital were investigated. Digital tape recordings of the alarms were made and analysed using masked-threshold software developed at the Université de Montréal. The digital recordings were also presented to the hospital personnel responsible for monitoring these alarms on an individual basis in order to determine how many of the alarms they would be able to identify when they heard them. Several of the alarms in both areas of the hospital could mask other alarms in the same area, and many of the alarms in the operating rooms could be masked by the sound of a surgical saw or a surgical drill. The staff in the OR (anaesthetists, anaesthesia residents, and OR technologists) were able to identify a mean of between 10 and 15 of the 26 alarms found in their operating theatres. The ICU nurses were able to identify a mean of between 9 and 14 of the 23 alarms found in their ICU. Alarm importance was positively correlated with the frequency of alarm identification in the case of the OR, rho = 0.411, but was not significantly correlated in the case of the ICU, rho = 0.155. This study demonstrates the poor design of auditory warning signals in hospitals and the need for standardization of alarms on medical equipment.

Adult↗
PubMed2003

Loudness adaptation: fact or artifact?

In the present study, the authors tested the hypothesis that contrast effects confound the Ipsilateral Comparison Paradigm (ICP). Bidirectional referents were used in which base tones of 50 or 70 dB alternated with referents of greater or lesser intensity in a 3.5-min listening period. The contrast hypothesis leads to the expectation that the bidirectional referents would produce opposing effects that should nullify time-based loudness changes in the common base tone. Contrary to that expectation, base-tone loudness declined significantly over time in the context of the bidirectional referents, and the loudness of the referents also declined significantly over time. Thus, the results of the study testified to the validity of the ICP as a contrast-free measure of broad-based loudness adaptation.

Adolescent↗
PubMed1992

Verbal indicators of depression.

Speech content, voice quality, and temporal pacing of speech were evaluated for 11 well and 11 depressed women. Sadness was the dominant mood of the depressed women's speech, whereas happiness and mood neutrality characterized the well women's speech. The well women's tone of voice changed with the content of their speech. The well women spoke with a wide range of fundamental frequency, and the average fundamental frequency of their voices changed according to speech content. In contrast, the depressed women spoke with a narrow range of fundamental frequency, and the average fundamental frequency of their speech was unaffected by speech content. The depressed women spoke with longer pauses than the well women did. The results of this study contribute to the understanding of measures for assessing depression.

Adult↗
PubMed2003

The speech and vocalization patterns of boys with ADHD compared with boys with dyslexia and boys without learning disabilities.

This research study dealt with an inquiry into the speech and vocalization patterns of boys with Attention Deficit Hyperactivity Disorder (ADHD) who were not under the influence of stimulating medication, compared with the speech and vocalization patterns of boys with reading disabilities and a control group of learners without learning disabilities. The voices of 105 participants were recorded during interviews and analyzed in the laboratory using equipment that examined the temporal speech patterns and physical features of vocalization. The speech patterns were examined with a frequency examination, speech unit length duration, and correlation between the vocalization and pauses in the speech unit. The physical features of vocalization were examined with volume and frequency scales. The research results indicated that the speech and vocalization patterns of boys with ADHD were significantly different from those of boys with reading disabilities and from the boys in the control group. The results support the assumption that speech and vocalization indicators can be used as objective indicators for the diagnosis of hyperactivity syndrome with attention and concentration difficulties.

Articulation Disorders↗
PubMed2001

Speech-evoked cortical potentials and speech recognition in cochlear implant users.

Processing in the auditory cortex may play a role in the unexplained variability in cochlear implant benefit. P300 and N1/P2 were elicited in post-lingually deaf cochlear implant users wearing a Nucleus multichannel cochlear implant. Four sound contrasts were presented (500-1,000 Hz, /ba/-/da/, /ba/-/pa/ and /i/-/a/). N1 and P2 were present in all subjects for all conditions. Prolonged N1, P2 and P300 latencies were found in the cochlear implant group compared to a control group of subjects with normal hearing. Cochlear implant users show smaller amplitudes of N1 for all the speech signals as well as smaller amplitudes of P2 for the consonants compared to the controls. P300 results of the cochlear implant users were compared to behavioural results of speech recognition testing. A relation was found between P300 amplitude and magnitude for the 500-1,000 Hz and /i/-/a/ contrasts and behavioural speech recognition in cochlear implant users. The results suggest that P300 measurements are useful and have additional value to speech recognition evaluations in cochlear implant users.

Adolescent↗
PubMed1981

Experimental study on quantitative flow measurement by a Doppler flowmeter with a sound-spectrograph.

A bidirectional ultrasonic Doppler flowmeter equipped with a sound-spectrographic analyzer has enabled us to determine blood-flow direction and to obtain useful information from the flow pattern in assessing the cerebral blood flow transcutaneously or intraoperatively. Using a regulated flow system produced in a dog, we performed an experimental study in order to establish the optimal mode for its use and to study the reliability in the quantitative cerebral blood-flow measurements. Although we could not measure the absolute blood-flow volume directly with this apparatus, we were able to obtain useful, quantitative information on blood flow and flow pattern by placing the ultrasonic probe in an appropriate position with respect to a blood vessel.

Animals↗