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At least 1,081 records · Page 60Linked to original sources
PubMed1992

Non-invasive determination of systolic blood pressure by heart sound pattern analysis.

A new concept of non-invasive blood pressure measurement by heart sound pattern analysis is described. The known diagnostic criterion of the 'accentuated' second heart sound of a hypertensive patient is here converted into a computer-aided pattern-recognition process for the second heart sound, applicable over the entire scale of blood pressure. After a 'learning phase', during which the second heart sound is recorded, analysed and correlated with a set of systolic blood pressure values of the individual patient, the computer is able to determine systolic blood pressure of the same patient from the acoustic spectrum of the second heart sound with sufficient precision. The method is in principle suited for automatically repeated blood pressure measurements, but further development is still needed for conversion into a widely practicable procedure.

Blood Pressure↗
PubMed2006

A dynamic method to estimate the time split between the A2 and P2 components of the S2 heart sound.

The time interval between the aortic (A2) and the pulmonary (P2) components of the second heart sound (S2) is an indicator of pulmonary arterial pressure. However, knowledge of the A2 and P2 components of the S2 sound is difficult to obtain due to their temporal overlap and significant spectral similarity. In this work, we aim to extract the A2 and P2 components from the phonocardiogram to estimate the time interval between them. We attain our objective by first isolating the S2 sound from the phonocardiogram by utilizing the mode complexity of the heart. Then, we assume the statistical independence of the A2 and P2 components and extract them from the S2 sound by the application of blind source separation techniques. Once separated, the time interval between the A2 and P2 components is estimated with a time-centroid-based method. Experimental results using simulated data show excellent performance of the proposed algorithm to extract the A2 and the P2 components from the S2 sound and to estimate the time interval between them. Results obtained from real data are also encouraging and show promise for utilizing the proposed method in a clinical setting to non-invasively tract pulmonary hypertension.

Algorithms↗
PubMed1993

Sound localization in acallosal human listeners.

In order to evaluate the callosal and hemispheric involvement in sound localization, the present study examined response accuracy to auditory targets in acallosal subjects. The primary interest was to determine whether the congenital absence of the corpus callosum affects auditory localization, especially for sounds situated near the midline of auditory space or moving across it. A corollary objective was to examine the possible existence of an hemispheric asymmetry on audio-spatial localization tasks. Four subjects with callosal agenesis paired to four age and IQ-matched controls and 16 normal control subjects were asked to locate broad band noise bursts at fixed intensity (52 dB sound pressure level) in the horizontal plane in an anechoic chamber. Broad band noise bursts were delivered randomly through 16 loudspeakers, which were mounted at approximately 10 degrees intervals on a perimeter frame. Two conditions were tested: (i) localization of a fixed-sound source; (ii) localization of the beginning and the end of a simulated moving stimulus. Two response modes were used. Listeners reported the apparent stimulus location either (i) by pointing with the ipsilateral index finger or (ii) by calling out the estimated angles indicated on the calibrated sound perimeter. Aiming accuracy was assessed by calculating the mean deviation of the response from the objective target position. The results indicated that the responses of the acallosal subjects were less accurate than those of the controls. The deficit was observed not only at the midline but throughout the auditory field. This points to possible compensatory mechanisms following the early absence of the corpus callosum which are, however, limited. The results obtained with manual pointing were generally more precise than those obtained through oral responses. This difference suggests that the remapping of spatial positions onto a verbally based coordinate system involves a supplementary cognitive step which affects the precision of the response. Comparing the performance to stimulus presentation in the left and right fields indicated that no hemispheric asymmetry was apparent under any of the conditions for either the acallosal subjects or the IQ-matched and normal control subjects.

Adolescent↗
PubMed2002

Sound localization in callosal agenesis and early callosotomy subjects: brain reorganization and/or compensatory strategies.

In order to evaluate the callosal involvement in sound localization, the present study examined the response accuracy of acallosal and early callosotomized subjects to monaural and binaural auditory targets presented in three-dimensional space. In these subjects, bilateral localization cues, such as interaural time and level differences, are integrated at the cortical and subcortical levels without the additional support of the callosal commissure. Because acallosal and early-callosotomized subjects have developed with this reduced source of binaural activation of cortical cells, they might have perfected their ability to use monaural sound localization cues. This hypothesis was tested by assessing localization performance under both binaural and monaural listening conditions. Five subjects with callosal agenesis, one callosotomized subject operated early in life and 19 control subjects were asked to localize broad-band noise bursts (BBNBs) of fixed intensity in the horizontal plane in an anechoic chamber. BBNBs were delivered through randomly selected loudspeakers. Two conditions were tested: (i) localization of a stationary sound source; and (ii) localization of a moving sound source. Listeners had to report the apparent stimulus location by pointing to its perceived position on a graduated perimeter. The results indicated that the acallosal subjects were less accurate than controls, but only in the binaural moving sound condition. More interestingly, in the monaural testing conditions, some of the acallosal subjects and the early-callosotomized subject performed significantly better than control subjects. This suggests that, because of the absence of the corpus callosum, these subjects compensate for their reduced access to cortically determined binaural cues by making more efficient use of monaural cues.

Acoustic Stimulation↗
PubMed2001

Impact of reduced reverberation time on sound-induced arousals during sleep.

The effect of reducing reverberation time was studied in 12 subjects during sleep. EEG-arousals following specific sound stimuli were significantly reduced (p<0.007) when reverberation time was reduced with sound-absorbing ceiling-tiles. On average reverberation was reduced 0.124 seconds at similar sound levels. It is proposed that increased sound absorption, i.e. reduced reverberation time, by contributing to a better acoustic environment may reduce sound-induced sleep fragmentation.

Adult↗
PubMed1999

Bourdonnement and other benign temporary breast implant sounds.

During the early postoperative period, a variety of sounds may be detected emanating from the augmented breast. These sounds are nearly always benign and are temporary. The sounds can be described as crepitation, popping, sloshing, squeaking, buzzing, and humming, and a new term, bourdonnement, is applied to one of these phenomena. Patients are understandably alarmed by sounds emanating from their breasts, and it is helpful for the surgeon to be able to discuss them, and to reassure the patient of the lack of any long-term significance of the phenomena. This report includes intraoperative techniques by which some of the sounds can be avoided or minimized.

Breast Implants↗
PubMed2004

Does familiarity facilitate the cortical processing of music sounds?

Automatic cortical sound discrimination, as indexed by the mismatch negativity (MMN) component of the auditory evoked potential, is facilitated for familiar speech sounds (phonemes). In musicians as compared to non-musicians, an enhanced MMN has been observed for complex non-speech sounds. Here, musically trained subjects were presented with sequences of either familiar (tonal) or structurally matched unfamiliar (atonal) triad chords, both with either fixed or randomly transposed chord root pitch. The MMN elicited by deviant chords did not differ for familiar and unfamiliar triad sequences, and was undiminished even to unfamiliar deviant sounds which were consciously undetectable. Only subsequent attention-related components indicated facilitated cognitive processing of familiar sounds, corresponding to higher behavioral detection scores.

Acoustic Stimulation↗
PubMed2002

Sound-direction identification, interaural time delay discrimination, and speech intelligibility advantages in noise for a bilateral cochlear implant user.

OBJECTIVES: To characterize some of the benefits available from using two cochlear implants compared with just one, sound-direction identification (ID) abilities, sensitivity to interaural time delays (ITDs) and speech intelligibility in noise were measured for a bilateral multi-channel cochlear implant user. METHODS: Sound-direction ID in the horizontal plane was tested with a bilateral cochlear implant user. The subject was tested both unilaterally and bilaterally using two independent behind-the-ear ESPRIT (Cochlear Ltd.) processors, as well as bilaterally using custom research processors. Pink noise bursts were presented using an 11-loudspeaker array spanning the subject's frontal 180 degrees arc in an anechoic room. After each burst, the subject was asked to identify which loudspeaker had produced the sound. No explicit training, and no feedback were given. Presentation levels were nominally at 70 dB SPL, except for a repeat experiment using the clinical devices where the presentation levels were reduced to 60 dB SPL to avoid activation of the devices' automatic gain control (AGC) circuits. Overall presentation levels were randomly varied by +/- 3 dB. For the research processor, a "low-update-rate" and a "high-update-rate" strategy were tested. Direct measurements of ITD just noticeable differences (JNDs) were made using a 3 AFC paradigm targeting 70% correct performance on the psychometric function. Stimuli included simple, low-rate electrical pulse trains as well as high-rate pulse trains modulated at 100 Hz. Speech data comparing monaural and binaural performance in noise were also collected with both low, and high update-rate strategies on the research processors. Open-set sentences were presented from directly in front of the subject and competing multi-talker babble noise was presented from the same loudspeaker, or from a loudspeaker placed 90 degrees to the left or right of the subject. RESULTS: For the sound-direction ID task, monaural performance using the clinical devices showed large mean absolute errors of 81 degrees and 73 degrees, with standard deviations (averaged across all 11 loud-speakers) of 10 degrees and 17 degrees, for left and right ears, respectively. Fore bilateral device use at a presentation level of 70 dB SPL, the mean error improved to about 16 degrees with an average standard deviation of 18 degrees. When the presentation level was decreased to 60 dB SPL to avoid activation of the automatic gain control (AGC) circuits in the clinical processors, the mean response error improved further to 8 degrees with a standard deviation of 13 degrees. Further tests with the custom research processors, which had a higher stimulation rate and did not include AGCs, showed comparable response errors: around 8 or 9 degrees and a standard deviation of about 11 degrees for both update rates. The best ITD JNDs measured for this subject were between 350 to 400 microsec for simple low-rate pulse trains. Speech results showed a substantial headshadow advantage for bilateral device use when speech and noise were spatially separated, but little evidence of binaural unmasking. For spatially coincident speech and noise, listening with both ears showed similar results to listening with either side alone when loudness summation was compensated for. No significant differences were observed between binaural results for high and low update-rates in any test configuration. Only for monaural listening in one test configuration did the high rate show a small significant improvement over the low rate. CONCLUSION: Results show that even if interaural time delay cues are not well coded or perceived, bilateral implants can offer important advantages, both for speech in noise as well as for sound-direction identification.

Adult↗
PubMed2003

Coding of sounds in the auditory system and its relevance to signal processing and coding in cochlear implants.

OBJECTIVE: To review how the properties of sounds are "coded" in the normal auditory system and to discuss the extent to which cochlear implants can and do represent these codes. DATA SOURCES: Data are taken from published studies of the response of the cochlea and auditory nerve to simple and complex stimuli, in both the normal and the electrically stimulated ear. REVIEW CONTENT: The review describes: 1) the coding in the normal auditory system of overall level (which partly determines perceived loudness), spectral shape (which partly determines perceived timbre and the identity of speech sounds), periodicity (which partly determines pitch), and sound location; 2) the role of the active mechanism in the cochlea, and particularly the fast-acting compression associated with that mechanism; 3) the neural response patterns evoked by cochlear implants; and 4) how the response patterns evoked by implants differ from those observed in the normal auditory system in response to sound. A series of specific issues is then discussed, including: 1) how to compensate for the loss of cochlear compression; 2) the effective number of independent channels in a normal ear and in cochlear implantees; 3) the importance of independence of responses across neurons; 4) the stochastic nature of normal neural responses; 5) the possible role of across-channel coincidence detection; and 6) potential benefits of binaural implantation. CONCLUSIONS: Current cochlear implants do not adequately reproduce several aspects of the neural coding of sound in the normal auditory system. Improved electrode arrays and coding systems may lead to improved coding and, it is hoped, to better performance.

Cochlea↗
PubMed2005

How does the sound pressure generated by circumaural, supra-aural, and insert earphones differ for adult and infant ears?

OBJECTIVE: To determine how the ear canal sound pressure levels generated by circumaural, supra-aural, and insert earphones differ when coupled to the normal adult and infant ear. DESIGN: The ratio between the sound pressure generated in an adult ear and an infant ear was calculated for three types of earphones: a circumaural earphone (Natus Medical, ALGO with Flexicoupler), a supra-aural earphone (Telephonics, TDH-49 with MXAR cushion), and an insert earphone placed in the ear canal (Etymoup and down arrow tic Research, ER-3A). The calculations are based on (1) previously published measurements of ear canal impedances in adult and infant (ages 1, 3, 6, 12, and 24 months) ears (Keefe et al., 1993, Acoustic Society of America, 94:2617-2638), (2) measurements of the Thévenin equivalent for each earphone configuration, and (3) acoustic models of the ear canal and external ear. RESULTS: Sound-pressure levels depend on the ear canal location at which they are measured. For pressures at the earphone: (1) Circumaural and supra-aural earphones produce changes between infant and adult ears that are less than 3 dB at all frequencies, and (2) insert earphones produce infant pressures that are up to 15 dB greater than adult pressures. For pressures at the tympanic membrane: (1) Circumaural and supra-aural earphones produce infant pressures that are within 2 dB of adult ears at frequencies below 2000 Hz and that are 5 to 7 dB smaller in infant ears than adult ears above 2000 Hz, and (2) insert earphones produce pressures that are 5 to 8 dB larger in infant ears than adult ears across all audiometric frequencies. CONCLUSIONS: Sound pressures generated by all earphone types (circumaural, supra-aural, and insert) depend on the dimensions of the ear canal and on the impedance of the ear at the tympanic membrane (e.g., infant versus adult). Specific conclusions depend on the location along the ear canal at which the changes between adult and infant ears are referenced (i.e., the earphone output location or the tympanic membrane). With circumaural and supra-aural earphones, the relatively large volume of air within the cuff of the earphone dominates the acoustic load that these earphones must drive, and differences in sound pressure generated in infant and adult ears are generally smaller than those with the insert earphone in which the changes in ear canal dimensions and impedance at the tympanic membrane have a bigger effect on the load the earphone must drive.

Acoustic Impedance Tests↗
PubMed2006

Design, construction, and evaluation of a bioacoustic transducer testing (BATT) system for respiratory sounds.

Many different transducers are employed for recording respiratory sounds including accelerometers and microphones in couplers. However, there is no standard lung sound transducer or any device to compare transducers so that measurements from different laboratories can be determined to be of physiologic origin rather than technical artifacts of the transducers. To address this problem, we designed and constructed a prototype of a device that can be used to compare accelerometers, microphones enclosed in couplers, and stethoscopes. The prototype device consists of a rigid chamber containing a loudspeaker that opens to an antechamber covered by a viscoelastic material with mechanical properties similar to human skin and subcutaneous tissue. When driven by a white noise source, we found the sound output at the surface to be useful to comparatively evaluate sensors between 100 and 1200 Hz where lung sounds have most of their spectral energy. We compared the viscoelastic layer to similar thicknesses of fresh meat and fat and found them to produce similar acoustic spectra. This device allows air-coupled transducers, accelerometers, and stethoscopes used in respiratory sounds measurements to be compared under physical conditions similar to their intended use.

Acoustics↗
PubMed2004

Left hemisphere motor facilitation in response to manual action sounds.

Previous studies indicate that the motor areas of both hemispheres are active when observing actions. Here we explored how the motor areas of each hemisphere respond to the sounds associated with actions. We used transcranial magnetic stimulation (TMS) to measure motor corticospinal excitability of hand muscles while listening to sounds. Sounds associated with bimanual actions produced greater motor corticospinal excitability than sounds associated with leg movements or control sounds. This facilitation was exclusively lateralized to the left hemisphere, the dominant hemisphere for language. These results are consistent with the hypothesis that action coding may be a precursor of language.

Adolescent↗
PubMed1989

Relative influence of plaque control, scaling and root planing on occlusal sounds.

Nine periodontally affected subjects and eight healthy subjects were selected in order to examine the effect of initial periodontal treatment on occlusal sounds. Gingival Index, probing depth, tooth mobility and occlusal sound duration via an occlusal sound analyser were recorded at the baseline. The nine periodontal patients were then treated by plaque control, root planing with general scaling and were re-examined at 1 month and 3 months post-operatively. The following results were obtained: (i) The normal duration of an occlusal sound is less than 10 ms. (ii) Occlusal sounds of periodontal patients were of longer duration compared with values in healthy subjects, but decreased and approached the normal value after treatment.

Adult↗
PubMed1990

Duration patterns of percussion sound in healthy and periodontally affected teeth.

Ten periodontally affected subjects and 10 healthy subjects were selected in order to examine the duration patterns of percussion sounds in all upper teeth, excluding the 8's. Probing depth, loss of attachment, tooth mobility by 'Periotest', bone loss and percussion sound duration via occlusal sound analyser were recorded during the pretreatment period. The following results were obtained from the study: (i) the normal duration of percussion sounds ranged from 4.40-5.33 ms; (ii) percussion sound values of periodontal patients were of longer duration than those of healthy subjects; (iii) a close correlation between duration and other individual parameters was found in all upper teeth, with the exception of molars.

Acoustics↗
PubMed1996

Classification of temporomandibular joint sounds based upon their reduced interference distribution.

Temporomandibular joint (TMJ) sounds were recorded in 98 orthodontic retention patients, mean age 19 +/- 8.6 (s.d.) years, by interview, auscultation and electronic recording. Sounds were found by auscultation in 41% and by interview in 32% of the subjects, more often in females than in males (P < 0.05). A new method for time-frequency analysis, the reduced interference distribution (RID), was used to classify the electronic sound recordings into five subclasses, RID types 1-5, based upon location and number of their energy peaks. RID types 1-3 had a few energy peaks close in time. RID types 4-5, typical of subjects with crepitation, had multiple energy peaks occurring close in time for a period of 20-300 ms. RID type 1, found in 45% of the subjects, typical of patients with clicking, had its dominant energy peak located in a frequency range < 600 Hz and was significantly more common in the female than in the male subjects (P < 0.01). RID type 2, found in 68% of the subjects, with the dominant peak in the range 600-1200 Hz, and RID type 3, found in 38% of the subjects, with the peak in the frequency range > 1200 Hz, were found to have a similar gender distribution. RID type 4, found in 49% of the subjects, had the energy peaks distributed in the frequency range < 600 Hz. RID type 5, found in 43% of the subjects, more often in females than in males (P < 0.05), had the peaks distributed over the whole frequency range from about 30 Hz up to about 3000 Hz. In conclusion, a more detailed classification could be made of the TMJ sounds by displaying the RIDs than by auscultation. This suggests that RID classification methods may provide a means for differentiating sounds indicating different types of pathology.

Adolescent↗
PubMed1996

The wave forms of temporomandibular joint sound clicking and crepitation.

The aim of the present study was to determine the sound wave forms which correspond to auscultatory findings of temporomandibular joint (TMJ) clicking and crepitation. Such knowledge is important when selecting parts of digital recordings for spectral analysis. Electronic digital recordings were made with a sampling rate of 44,100 Hz from 60 subjects, including 51 patients referred for suspected rheumatological disease and nine healthy subjects. Accelerometers with the bandwidth 20-3600 Hz were used for all subjects and complementary recordings were made from a subgroup of nine subjects using a measurement microphone with the bandwidth 20-20,000 Hz. The clicking sounds could be classified into different types according to differences in temporal period duration (T) as measured on the analogue display. One type of clicking, found in 51% of the patients, had a T of 2-20 ms. Another type, found in 70% of the subjects, had a T of less than 1 ms, often as low 0.2 ms. This type of clicking was not seen at all in the analogue display if the sampling rate was below 3,000 Hz. The character of the two types of clicking differed: the short duration sounds had a very high pitch, while the pitch of the longer duration sound was lower. Crepitation was found in 63% of the subjects and was observed to be composed of a series of short duration sounds, occurring with brief (less than 10 ms) intervals. It is concluded that the accelerometer (or microphone) bandwidth should cover the entire audible range (20-20,000 Hz), and that sampling rates must be much higher than 3000 Hz, and preferably greater than 10,000 Hz, before the true significance of electronically recorded joint sounds/vibrations can be determined.

Acceleration↗
PubMed1992

Development of sound localization.

Perceptual sound localization is determined from differences in time and loudness of signals arriving separately at bilateral ears, with the time difference being the more important one. The author examined the development of sound lateralization using a self-recording device developed by Sato. It measures the sensitivity of sound lateralization on the basis of time and loudness differences separately. Subjects were 59 children aged 2 to 18 years and 12 adults who were audiologically and neurologically normal. Sound stimulus was 500 Hz continuous band noise. (1) The testable rate was increased in children older than the age of 4, and all children over 7 years of age could be tested. (2) Children over 4 years of age could lateralize sound on the basis of time difference. Sensitivity to time differences improved rapidly, showing a steep curve, in children from the ages of 4 to 6, and then increased slowly until adulthood. (3) Sensitivity to loudness differences increased and standard deviation decreased with age. There is a possibility that children aged 4 can discriminate loudness difference almost as well as adults.

Adolescent↗
PubMed2007

Sound spectrogram analysis in patients receiving Kawahara's surgical voice restoration for advanced carcinoma of the hypopharynx and cervical esophagus.

Loss of voice after total laryngectomy is a major concern that has prompted much effort to develop methods of surgical voice restoration. In 1992, Kawahara described a tracheocolic shunt for voice restoration using a revascularized ileocolic graft. With this method, aspiration through the phonatory shunt is prevented by the ileocolic valve (Bauhin's valve), while vocalization is allowed. The purpose of this study was to use sound spectrogram analysis to evaluate voices surgically restored in that way. Between 2002 and 2005, 10 consecutive patients underwent laryngopharyngoesophagectomy with Kawahara's surgical voice restoration for advanced carcinoma of the hypopharynx and/or cervical esophagus at Akita University Hospital, Japan. We then used sound spectrography to analyze and compare the voices of patients receiving Kawahara's voice restoration, against healthy volunteers and patients who underwent the same surgery without voice restoration and spoke using an electronic larynx. We also evaluated the intelligibility of conversation and performed a listening test. The sound spectrograms showed that when produced by the electronic larynx, consonant sounds and voice frequencies below 300 Hz were not clearly recognized. By contrast, in patients who received Kawahara's surgical voice restoration, consonant and vowel sounds at frequencies above and below 300 Hz were clearly recognized. Although conversation was intelligible with both Kawahara's surgical voice restoration and the electronic device, listeners judged the voice produced by the former to be superior. Thus, the voice produced by Kawahara's surgical voice restoration is superior to that produced by the electronic larynx.

Aged↗