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PubMed1999

Amplitude and frequency spectrum of temporomandibular joint sounds from subjects with and without other signs/symptoms of temporomandibular disorders.

Temporomandibular joint (TMJ) sound is one of the most commonly recognized signs in patients with temporomandibular disorders (TMD) but is also frequently seen in asymptomatic individuals. Sound recording is therefore only meaningful if the sounds from a normal healthy joint can be differentiated from those in patients. In this study, the amplitude and power spectrum of the TMJ sounds from symptomatic patients and asymptomatic individuals were recorded and compared. The result showed that TMJ sounds from symptomatic patients had a larger amplitude than sounds from asymptomatic subjects. A significant proportion of sounds had frequencies between 2000 and 3000 Hz. It was concluded that the characteristic amplitude is worthy of further study as a sign of possible diagnostic value. Secondly, the bandwidth of the sensors used at electronic TMJ sound recording should not be less than 3000 Hz.

Acoustics↗
PubMed2000

Spectral characteristics of hypernasality in maxillectomy patients.

To reveal the acoustic characteristics associated with hypernasality and to ascertain their correlation to the severity of hypernasality, 30 speech samples produced by 15 maxillectomy patients were acoustically analysed with and without an obturator prosthesis in place. The isolated, sustained Japanese vowel /i/ was used as the stimulus for acoustic measurement and perceptual judgment to evaluate the severity of hypernasality. Normalized 1/3-octave spectral analysis demonstrated the spectral characteristics of hypernasality as a rise in amplitude between the first and second formants around the 1 kHz region, and a reduction in amplitude of the frequencies higher than the second formant. High correlation was shown between the perceptual ratings and the predicted values derived from stepwise regression analysis.

Adult↗
PubMed2000

Computer aided gnathosonic analysis: distinguishing between single and multiple tooth impact sounds.

Watt developed a classification of tooth contact sounds that distinguished between the short sharp, reproducible sounds heard when the teeth meet simultaneously and the dull prolonged, poorly reproducible sounds heard when tooth contacts are sequential. However, when a large occlusal prematurity, for instance a high restoration, is introduced, tooth contact sounds are also short sharp and highly reproducible. In this study, a method of distinguishing single from multiple tooth contact sounds is described, based on an analysis of the phase and amplitude of sounds detected by headphones placed over the ears.

Adult↗
PubMed2000

Effect of temperature and flux concentration on soldering of base metal.

The present study used the acoustic emission (AE) technique to evaluate interactions among soldering temperature, flux treatment, and the resultant ultimate tensile strength (UTS). Scanning electron microscopy (SEM) was used to examine fracture surfaces of the solder joints. Specimens were cast from removable partial denture alloy and then placed in a jig with a gap distance of 1.0 mm. A high-frequency soldering machine with an optical pyrometer was used for soldering at 1150 degrees C and 1200 degrees C, respectively. The flux concentrations were 67% and 75%. The soldered specimens were subjected to tensile test at a crosshead speed of 0.05 mm/min. During testing, acoustic emissions in the frequency range of 100--1200 kHz were collected, filtered, recorded, and processed by a sensing device. The results were analysed by ANOVA and Tukey LSD test. UTS at different temperatures showed no significant difference according to either mechanical or acoustic results. But in the 1200 degrees C group, the UTSs and AE counts showed significant differences (P<0.05) at both flux concentrations. SEM showed that the 1200C group had better dendritic crystal structure than did the 1150 degrees C group. In the 1200 degrees C group specimens with 67% flux had fewer flux inclusion bodies and dendritic crystals than did specimens with 75% flux. The 75% flux subgroup produced high-amplitude (60--70 dB) acoustic signals within the elastic deformation zone, while the 67% flux subgroup produced similar signals within the plastic deformation zone, either beyond the 0.2% yield point or before fracture.

Acoustics↗
PubMed2002

Acoustic characteristics of sounds from temporomandibular joints with and without effusion: an MRI study.

Joint effusion has been associated with temporomandibular joint (TMJ) pain but can only be diagnosed by magnetic resonance imaging (MRI). For screening of patients with suspected effusion a simple and less expensive method would be desirable. We recorded joint sounds during jaw opening and closing movement from 34 TMJs with internal derangement (ID). Seventeen joints had joint effusion seen on MRI. Spectrograms of the sounds were displayed as waterfall plots showing profiles of the consecutive Hamming windows. If the profiles were similar, as judged by initial evaluation, the displayed pattern was classified as stable. If some profiles were distinctly deviating in their pattern, this was classified as unstable. Joints with effusion showed unstable sound pattern more often than joints without effusion (P < 0.001). It was concluded that TMJ sound analyses have a potential to identify joints with effusion based on their unstable sound pattern.

Adult↗
PubMed2002

Digital acoustic analysis of five vowels in maxillectomy patients.

The aim of the study was to characterize the acoustics of vowel articulation in maxillectomy patients. Digital acoustic analysis of five vowels, /a/, /e/, /i/, /o/ and /u/, was performed on 12 male maxillectomy patients and 12 normal male individuals. A simple set of acoustic descriptions called the first and second formant frequencies, F1 and F2, were employed and calculated based on linear predictive coding. The maxillectomy patients had a significantly lower F2 for all five vowels and a significantly higher F1 for only /i/ vowel. From the data plotted on an F1-F2 plane in each subject, we determined the F1 range and the F2 range, which are the differences between the minimum and the maximum frequencies among the five vowels. The maxillectomy patients had a significantly narrower F2 range than the normal controls. In contrast, there was no significant difference in the F1 range. These results suggest that the maxillectomy patients had difficulty in controlling F2 properly. In addition, the speech intelligibility (SI) test was performed to verify the results of this new frequency range method. A high correlation between the F2 range and the score of SI test was demonstrated, suggesting that the F2 range is effective in evaluating the speech ability of maxillectomy patients.

Acoustics↗
PubMed1999

Intensity of snoring in patients with sleep-related breathing disorders.

The intensity of snoring was measured in 73 patients with snoring or sleep apnea using a noise meter. The mean intensity of snoring at 50 cm in front of the mouth was 61.7 dB in the supine position and 53.7 dB in the lateral position. There existed a definite correlation between the logarithmic transformation of the intra-esophageal pressure amplitude and the intensity of snoring in the supine and lateral decubitus positions. These findings suggest that the intensity of snoring may be a useful index for sleep-related breathing disorders.

Adult↗
PubMed2000

Acoustic parameters of voluntary cough in healthy non-smoking subjects.

OBJECTIVE: The aim of this study was to explore cough in healthy subjects. METHODOLOGY: We studied 234 coughs generated by 24 (12 males) healthy non-smokers (forced expiratory volume in 1 s (FEV1) 103+/-8% of predicted), who had no significant differences in FEV1 and age between males and females. For each subject, several bouts of voluntary coughing were recorded using a personal computer with an A/D converter (sampling rate 10 kHz, 8 bit resolution) and the first and second coughs of each bout were analysed using short-time Fast Fourier Transformation. For each cough we studied the three phases that are produced. In particular, we studied the duration of the three parts, loudest frequency in the first part, lowest and highest frequencies, number of continuous frequencies and lowest and highest continuous frequencies in the second part, and the loudest frequency of the third part if present. RESULTS: We found significant differences between males and females in length of the first part (41.4+/-14 vs 44.7+/-10.4 msec, P = 0.04), loudest frequency of the first part (362+/-145 vs 449+/-145 Hz), lowest frequencies (282+/-100 vs 348+/-135 Hz) and highest continuous frequencies (3877+/-571 vs 4147+/-362 Hz; P < 0.001) of the second part. An interesting finding was that healthy males and females had the same number of continuous frequencies. Different frequencies are probably a consequence of anatomical differences in airway geometry involved in the cough. CONCLUSION: In cough frequency spectrum studies the differences between the two sexes should be taken into account to reduce the variability of the results.

Acoustics↗
PubMed2003

Influence of the rheological properties of airway mucus on cough sound generation.

OBJECTIVES: There have been several reports regarding the role of airway mucus in cough sound generation, but the properties of the mucus that influence cough sound generation remain unclear. The aim of this study was to elucidate the influence of the rheological properties of airway mucus on cough sound generation. METHODOLOGY: The acoustic properties of voluntary cough sounds from 15 patients with chronic productive cough and nine controls with dry cough were analyzed by dividing the energy envelope of the sounds into three phases and computing the root mean square values and the duration of each phase as a proportion of the total cough duration. The rheological properties of the airway mucus (yield value, ciliary transportability and spinability) were also measured. Differences between productive and dry cough sounds, and correlations between the acoustic properties of cough sounds and the rheological properties of the airway mucus, were analyzed. RESULTS: The acoustic properties of productive and dry cough sounds differed significantly (P < 0.05). The acoustic properties of second phase cough sounds correlated significantly with the yield value and ciliary transportability of the airway mucus (P < 0.05). CONCLUSIONS: The rheological properties of the airway mucus influenced cough sound generation.

Adult↗
PubMed1998

Direct evidence of cubic difference tone propagation by intracochlear acoustic pressure measurements in the guinea-pig.

The fine tuning mechanisms involved in the normal processing of sound in the cochlea are non-linear, hence combination tones are generated inside the cochlea when a pair of low-level pure tones with neighbouring frequencies f1 and f2 is used as a stimulus. Their detection as sounds in the ear canal proves that they undergo backward propagation in the cochlea and through the middle ear, and the non-invasive measurement of the combination tone at 2f1-f2, called the cubic difference tone (CDT), has become a routine method of monitoring cochlear function. In order to gain information on the hypothetical places where CDTs are generated, on their intracochlear levels and propagation velocities, direct measurements of CDT pressure waves were carried out in scala vestibuli and tympani of the first and second turn of the guinea-pig cochlea. Cubic difference tones at 2f1-f2 varied from 0.75 to 9 kHz and were measured with a miniature piezoresistive transducer. Its high sensitivity allowed the detection of CDTs whenever their levels exceeded 5 dB SPL in the ear canal, i.e. 40 dB SPL (re: 20 microPa) inside the cochlea. The levels of CDTs were similar in scala vestibuli of the first and second turn. Phase comparisons between measurements at 2f1-f2 in the first and second turn allowed determination of the place where the CDT phase was minimum. It provided an estimation of the generation site of the CDT, which appeared to be close to the place tuned to f2 for stimulus levels lower than 70 dB SPL. Forward and backward travel times from one turn to the other were assessed at several frequencies, and both values were shorter than 0.2 ms. In contrast, the overall 'round-trip' delay of CDTs, measured in the ear canal, was about five times larger, suggesting that local filtering processes rather than propagation delays account for the overall CDT delay.

Acoustic Stimulation↗
PubMed2003

Tonotopic representation of missing fundamental complex sounds in the human auditory cortex.

The N1m component of the auditory evoked magnetic field in response to tones and complex sounds was examined in order to clarify whether the tonotopic representation in the human secondary auditory cortex is based on perceived pitch or the physical frequency spectrum of the sound. The investigated stimulus parameters were the fundamental frequencies (F0 = 250, 500 and 1000 Hz), the spectral composition of the higher harmonics of the missing fundamental sounds (2nd to 5th, 6th to 9th and 10th to 13th harmonic) and the frequencies of pure tones corresponding to F0 and to the lowest component of each complex sound. Tonotopic gradients showed that high frequencies were more medially located than low frequencies for the pure tones and for the centre frequency of the complex tones. Furthermore, in the superior-inferior direction, the tonotopic gradients were different between pure tones and complex sounds. The results were interpreted as reflecting different processing in the auditory cortex for pure tones and complex sounds. This hypothesis was supported by the result of evoked responses to complex sounds having longer latencies. A more pronounced tonotopic representation in the right hemisphere gave evidence for right hemispheric dominance in spectral processing.

Acoustic Stimulation↗
PubMed2002

Acoustic and perceptual analysis of the sibilant sound /s/ before and after orthognathic surgery.

PURPOSE: Orthognathic surgery may have a positive or negative effect on speech. Perceptual evaluation of presurgical and postsurgical articulation is difficult because speech errors, when they occur, are usually fricative distortions, which may be difficult to document reliably. In this study, acoustic analysis was used to supplement perceptual judgment of presurgical and postsurgical productions of /s/. SUBJECTS AND METHODS: The study population consisted of 9 Cantonese speakers undergoing osteotomy for Class III skeletal deformity and 9 age- and gender-matched adults with normal occlusion and speech. The speech sample consisted of 6 words with the initial sibilant sound /s/. Perceptual analysis included narrow phonetic transcription and classification of error types. Acoustic analysis included measurement of first and second spectral peaks, fricative duration, noise bandwidth, and noise-to-vowel decibel ratio. RESULTS: The results of the perceptual analysis showed a decrease in articulatory errors for the group after surgery, although 5 patients had no perceptual errors before surgery. Acoustic analysis showed significant differences between the experimental and control groups before surgery for 2 variables (spectral peak I and bandwidth). Three months after surgery there were no significant differences between the control group and the experimental group, except for bandwidth. Twelve months after surgery, there were significant differences between the 2 groups in noise bandwidth and spectral peak II. CONCLUSIONS: The results suggest a possible relapse at 1 year after surgery, based on spectral peak values. Osteotomy appears to result in a positive change in articulation for most patients, but speech outcome after osteotomy must be evaluated both 1 year and shortly after surgery.

Adult↗
PubMed2002

Effects of transitory lingual nerve impairment on speech: an acoustic study of vowel sounds.

PURPOSE: The purpose of the study was to evaluate the effects of the lingual nerve impairment on phonetic quality of speech by analyzing the main acoustic features of vowel sounds when the normal lingual nerve function was partly distorted by local anesthesia. PATIENTS AND METHODS: The study group consisted of 7 men, whose right side lingual nerve was anesthetized with 0.8 mL of Ultracaine D-Suprarenin (Aventis Pharma Deutschland GmpH, Frankfurt am Main, Germany). The speech material analyzed consisted of 8 vowels produced in sentence context by speakers. Every utterance was repeated 10 times with and without local anesthesia. After recording, the speech samples were analyzed with a computerized speech laboratory. In addition, the vowels of 1 man with permanent nerve impairment were studied. RESULTS: The results show that the deprived function of the tongue after lingual nerve impairment had various effects on vowel quality for every subject. The main acoustic determinants of different vowels, the lowest vocal tract resonances, changed in frequency. In addition, the total duration of vowels changed and the vowels had different fundamental frequencies. However, these effects were extremely individual and variable. CONCLUSIONS: According to the results of acoustic analysis, the distortion of lingual nerve function has effects on vowel production. Some of these changes were so extensive that they also could be perceptually detectable. Lingual nerve impairment seems to have potential to change speech production.

Acoustics↗
PubMed2001

Flextube reflectometry for localization of upper airway narrowing--a preliminary study in models and awake subjects.

The aim of this study was to examine an acoustic reflection method using a flexible tube for identifying the obstructive site of the upper airway in snorers and patients with obstructive sleep apnoea (OSA). As a preliminary study it was performed n models and subjects in the awake state. Flextube narrowing was produced in a model of the nose and pharynx and three blinded observers assessed the obstructive level. The correlation between pharyngeal narrowing assessed by endoscopy and by acoustic measurement during Müller manoeuvres was also examined in 10 OSA patients and 11 healthy non-snoring, adults. Three blinded observers dentified the level of 176 of 180 random cases of flextube narrowing in a polycarbonate model correctly The level of narrowing was always correctly evaluated within 1.9 mm. Pharyngeal area decrease was measured by the flextube method during the Müller manoeuvre but it was not closely related to the findings by endoscopy. In conclusion the flextube reflectometry method was able to demonstrate narrowng in a model of the nose and pharynx in a precise way. Narrowing was also observed during Müller manoeuvres. Flextube reflectometry may be a promising method to detect upper airway narrowing but further evaluation during sleep is required.

Adult↗
PubMed2001

Flextube reflectometry for determination of sites of upper airway narrowing in sleeping obstructive sleep apnoea patients.

The aim of this study was to examine a new technique based on sound reflections in a flexible tube for identifying obstructive sites of the upper airway during sleep. There was no significant difference between two nights in seven obstructive sleep apnoea (OSA) patients regarding the level distribution of pharyngeal narrowings, when the pharynx was divided into two segments (retropalatal and retrolingual). We also compared the level distribution determined by magnetic resonance imaging (MRI) with the level distribution found by flextube reflectometry in seven OSA patients. There was no significant difference between flextube and MRI level distributions during obstructive events, but due to few subjects the power of the test was limited. We found a statistically significant correlation between the number of flextube narrowings per hour of sleep and the number of obstructive apnoeas and hypopnoeas per hour of sleep determined by polysomnography (PSG) in 21 subjects (Spearman's correlation coefficient r = 0.79, P < 0.001). In conclusion, the flextube reflectometry system seems to be useful for level diagnosis in OSA before and after treatment.

Adult↗
PubMed1999

[Acute hearing loss and tinnitus caused by amplified recreational music].

BACKGROUND: Hearing loss resulting from exposure to permanent or repeated amplified music in professional musicians and music consumers is described in literature. The risk of hearing loss does not exist only after prolonged exposure to music. Short-term exposure to very high sound levels, for example in concerts, can also cause hearing loss and tinnitus. PATIENTS: The retrospective study includes 24 patients who required rheologic therapy between 1994 and 1997 due to a music related acoustic trauma. The type, intensity, and length of music exposure as well as the distance and the position to the source of noise were examined. The type of hearing damage and its development during rheological treatment was studied by pure-tone audiometry. RESULTS: In the majority of examined patients (67%) the hearing loss developed on the basis of one-time exposure at a rock concert or pop concert, followed by hearing loss from attending discotheques (17%) or parties (12%), and music exposure from personal cassette players (4%). The majority of patients showed a maximum hearing loss of 40-60 dB (A) in a frequency between 3 kHz and 4 kHz. Pure-tone audiometry in 58% of the patients exhibited a unilateral threshold in a frequency between 3 kHz and 4 kHz combined with ipsilateral tinnitus of the same frequency. Twenty-one percent of the patients showed a symmetric bilateral threshold and tinnitus between 3 kHz and 4 kHz. In 8% there was a unilateral tinnitus, and in 13% a bilateral tinnitus without any hearing loss. All patients improved their hearing loss during rheologic treatment. Improvement in the tinnitus was only achieved in 33% of the examined cases. CONCLUSION: The risk of permanent hearing loss resulting from short-term exposure to amplified music is low compared to the risk of continuous tinnitus. Given the lack of acceptance of personal ear protectors, the risk of acute hearing damage due to amplified music could be reduced by avoiding the immediate proximity to the speakers.

Acute Disease↗