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PubMed2005

Quantifying the effect of compression hearing aid release time on speech acoustics and intelligibility.

Compression hearing aids have the inherent, and often adjustable, feature of release time from compression. Research to date does not provide a consensus on how to choose or set release time. The current study had 2 purposes: (a) a comprehensive evaluation of the acoustic effects of release time for a single-channel compression system in quiet and (b) an evaluation of the relation between the acoustic changes and speech recognition. The release times under study were 12, 100, and 800 ms. All of the stimuli were VC syllables from the Nonsense Syllable Task spoken by a female talker. The stimuli were processed through a hearing aid simulator at 3 input levels. Two acoustic measures were made on individual syllables: the envelope-difference index and CV ratio. These measurements allowed for quantification of the short-term amplitude characteristics of the speech signal and the changes to these amplitude characteristics caused by compression. The acoustic analyses revealed statistically significant effects among the 3 release times. The size of the effect was dependent on characteristics of the phoneme. Twelve listeners with moderate sensorineural hearing loss were tested for their speech recognition for the same stimuli. Although release time for this single-channel, 3:1 compression ratio system did not directly predict overall intelligibility for these nonsense syllables in quiet, the acoustic measurements reflecting the changes due to release time were significant predictors of phoneme recognition. Increased temporal-envelope distortion was predictive of reduced recognition for some individual phonemes, which is consistent with previous research on the importance of relative amplitude as a cue to syllable recognition for some phonemes.

Adult↗
PubMed1990

Acoustic analysis of voice in amyotrophic lateral sclerosis: a longitudinal case study.

Acoustic measures of phonatory instability (coefficient of variation for amplitude, coefficient of variation for frequency, shimmer, jitter, and harmonics-to-noise ratio), phonatory limits (maximum fundamental frequency range and maximum duration of vowel phonation), and the nasal-oral amplitude ratio were measured five times throughout a 6-month period from the phonation of a 69-year-old male patient with amyotrophic lateral sclerosis (ALS), an age- and sex-matched control subject, and on one occasion from a 16-subject control group matched to the patient in age and sex. The patient was free of vocal symptoms at the initiation of the study. When compared to the other recording sessions, the final recording of the ALS patient was characterized by increased coefficient of variation for amplitude, increased coefficient of variation for frequency, increased shimmer, increased jitter, reduced harmonics-to-noise ratio, and reduced maximum vowel duration. These acoustic manifestations of increased phonatory instability and reduced phonatory limits over time were in contrast to the consistency observed in the phonation of the longitudinal control subject and were outside the range of plus or minus one standard deviation on most acoustic variables when compared to the control group. These findings support the potential use of acoustic analysis in reflecting progression of ALS and suggest the need for further studies to investigate the relationship between acoustic analysis of voice and manifestations of neurological disease.

Aged↗
PubMed1990

Acoustic validation of phonological knowledge and its relationship to treatment.

The speech of 4 phonologically disordered children with place and voicing errors affecting initial stop consonants was described through phonological and acoustic analyses. Productions of target voiced and voiceless alveolar and velar stops were transcribed and acoustically analyzed before and after treatment that was administered on a predetermined contrast. Three of the children produced significant, although largely imperceptible, differences in VOT for a given stop when it represented different adult stops. The presence of productive phonological knowledge, as inferred from acoustic data, facilitated rapid generalization of correct production of the treated contrast. In the absence of acoustically determined productive knowledge, a longer treatment period was necessary to achieve a lower level of production accuracy on the same treated contrast. Sources of speech sound errors for the 4 children were hypothesized by comparing the children's underlying representations determined from both acoustic and descriptive phonological data.

Child, Preschool↗
PubMed1979

Acoustic admittance and the aging ear.

Tympanograms were acquired from 60 subjects, 20 through 79 years of age, with normal hearing and no history of otic pathology. Acoustic conductance and acoustic susceptance at the tympanic membrane (GTM and BTM) were derived and acoustic admittance (YTM) was calculated. Statistical analysis of GTM, BTM and YTM showed no significant variation in values across age decades. Comparison of these data with previous reports suggests that the effect(s) of age on measures of static acoustic admittance, and presumably acoustic impedance, is complex.

Acoustic Impedance Tests↗
PubMed1986

Speech waveform perturbation analysis: a perceptual-acoustical comparison of seven measures.

The performance of seven acoustic measures of cycle-to-cycle variations (perturbations) in the speech waveform was compared. All measures were calculated automatically and applied on running speech. Three of the measures refer to the frequency of occurrence and severity of waveform perturbations in special selected parts of the speech, identified by means of the rate of change in the fundamental frequency. Three other measures refer to statistical properties of the distribution of the relative frequency differences between adjacent pitch periods. One perturbation measure refers to the percentage of consecutive pitch period differences with alternating signs. The acoustic measures were tested on tape recorded speech samples from 41 voice patients, before and after successful therapy. Scattergrams of acoustic waveform perturbation data versus an average of perceived deviant voice qualities, as rated by voice clinicians, are presented. The perturbation measures were compared with regard to the acoustic-perceptual correlation and their ability to discriminate between normal and pathological voice status. The standard deviation of the distribution of the relative frequency differences was suggested as the most useful acoustic measure of waveform perturbations for clinical applications.

Adult↗
PubMed1990

Acoustic correlates of vocal quality.

We have investigated the relationship between various voice qualities and several acoustic measures made from the vowel /i/ phonated by subjects with normal voices and patients with vocal disorders. Among the patients (pathological voices), five qualities were investigated: overall severity, hoarseness, breathiness, roughness, and vocal fry. Six acoustic measures were examined. With one exception, all measures were extracted from the residue signal obtained by inverse filtering the speech signal using the linear predictive coding (LPC) technique. A formal listening test was implemented to rate each pathological voice for each vocal quality. A formal listening test also rated overall excellence of the normal voices. A scale of 1-7 was used. Multiple linear regression analysis between the results of the listening test and the various acoustic measures was used with the prediction sums of squares (PRESS) as the selection criteria. Useful prediction equations of order two or less were obtained relating certain acoustic measures and the ratings of pathological voices for each of the five qualities. The two most useful parameters for predicting vocal quality were the Pitch Amplitude (PA) and the Harmonics-to-Noise Ratio (HNR). No acoustic measure could rank the normal voices.

Adult↗
PubMed1992

Variability of acoustic segment durations after prolonged-speech treatment for stuttering.

Existing literature suggests that one of the effects of treatment based on prolonged speech is increased durations of acoustic segments. However, the external validity of the data concerned may be questioned because the data were not based on spontaneous speech samples and were gathered from subjects with unknown treatment histories. With this in mind, the present investigation used young clients with no history of treatment based on prolonged speech and obtained pretreatment and posttreatment acoustic measures from spontaneous speech samples. Acoustic measures showed no significant posttreatment increases in durations of acoustic segments. However, for the acoustic measure of vowel duration and a measure of articulation rate, posttreatment speech samples showed significantly reduced variability. The potential theoretical and practical relevance of these findings is discussed.

Adolescent↗
PubMed1993

Relationships between acoustically determined knowledge of stop place and voicing contrasts and phonological treatment progress.

The speech of 7 children with phonological disorders (4 who failed to produce an initial voicing contrast for stops and 3 who failed to produce the alveolar-velar stop contrast) was analyzed for imperceptible acoustic distinctions for seemingly homophonous word pairs. Subjects were audio/video recorded before and during treatment as they produced minimal pairs containing their error and correct sound. Acoustic measures were VOT and CV locus equations. The presence of acoustic distinctions was taken as evidence for productive knowledge of the sound contrasts. Treatment was applied experimentally and progress was related to pretreatment productive knowledge inferred from acoustic distinctions. A shorter treatment period was observed for subjects attributed to have productive knowledge of the contrast being trained, as compared with those who had no knowledge. One of the 4 subjects with initial voicing errors produced an acoustic distinction between voiced and voiceless stops and required the shortest treatment period to establish the voicing contrast. Two of 3 subjects with velar fronting displayed coarticulatory characteristics of velars and required fewer treatment sessions in comparison with the subject with no such characteristics. Results are discussed in reference to other linguistic and nonlinguistic variables from which to predict treatment outcomes.

Articulation Disorders↗
PubMed1999

Acoustic variations in adductor spasmodic dysphonia as a function of speech task.

Acoustic phonatory events were identified in 14 women diagnosed with ADSD and compared to those of 14 women age-matched (+/-2 years) with no evidence of vocal pathology/dysfunction. The three acoustic parameters examined during sustained vowel production and reading included phonatory breaks, aperiodicity, and frequency shifts. Intra- and intermeasurer correlations showed high reliability for the measures. Findings indicated that those with ADSD produced a greater frequency of aberrant acoustic events than the controls during both tasks. For the group with ADSD, the amount and type of each event also varied with utterance type. The sustained vowel sample produced by those with ADSD consisted of a greater percentage of aperiodic segments followed by phonatory breaks and frequency shifts. During reading, frequency shifts were the predominant acoustic event, followed by phonatory breaks and aperiodicity. The advantage of segmenting the acoustic waveform into these measures and the relevancy of examining intertask performances by those with ADSD is discussed.

Adult↗
PubMed2000

Acoustic duration changes associated with two types of treatment for children who stutter.

The purpose of this study was (a) to examine in young children the effects of Speech Motor Training (SMT) on selected temporal acoustic durations considered to be related to speech motor programming, (b) to compare the speech motor effects of that treatment with those of a treatment of childhood stuttering that did not directly incorporate speech motor control training (Extended Length of Utterance [ELU]), and (c) to examine the relation of acoustic duration changes to reduction of stuttering. Twelve children who stutter were recorded while repeating syllable sets /see text/ and /see text/ before and after SMT (n = 6) or ELU treatment (n = 6). Children who did not stutter served as matched reference groups. The syllables beginning with /p/ and /t/ were used as tokens for the acoustic measurement. Five measures served as indicators of temporal aspects of speech motor performance: vowel duration, stop gap duration, voice onset time, stop gap/vowel duration ratio, and total token duration. Results indicated that following SMT there was a significant increase in vowel duration and some reduction in stop gap duration that resulted in significantly reduced stop gap/vowel duration ratios. These acoustic effects were consistent across most participants. The ELU treatment reduced stuttering more than the SMT, but was not accompanied by significant effects on the selected temporal acoustic measures. These findings are compared with previous findings of increased vowel durations associated with fluency enhancement and stuttering treatment. We speculate that the increased vowel durations allow more time for speech motor planning and that stuttering is reduced moderately as a by-product of longer vowel durations. The mechanism(s) by which ELU treatment reduces stuttering did not appear to be captured by the dependent variables measured in this study.

Child↗
PubMed2002

Clinical results with a new acoustic device to identify the epidural space.

Fifty patients scheduled for surgery under lumbar epidural anaesthesia were included in a study to evaluate the possibility of localising the epidural space solely by means of an acoustic signal. With an experimental set-up, the pressure generated during the epidural puncture procedure was translated into a corresponding acoustic signal. One anaesthetist held the epidural needle with both hands and detected the epidural space by means of this acoustic signal. At the same time, a second anaesthetist applied the loss of resistance technique and functioned as control. In all patients the epidural space was located with the acoustic signal. This was confirmed by conventional loss of resistance in 49 (98%) of the patients; in one patient (2%) it was not. We conclude that it is possible to locate the epidural space using an acoustic signal alone.

Acoustics↗
PubMed1998

Acoustic rhinometry: an explanation of some common artefacts associated with nasal decongestion.

The nasal cavities of 51 healthy volunteers were examined using acoustic rhinometry before and after nasal decongestant. Several specific dimensions were studied, which included the minimum cross-sectional area, and three volumes corresponding to the anterior, middle and posterior regions of the nasal airway. An average acoustic rhinometry trace was constructed for the whole group of subjects, before and after decongestion, from data extracted from the raw data files written to the computer hard disk for each subject. A 27.5% (P < 0.0001) increase in the minimum cross-sectional area was observed, with no shift in its position. The greatest increase in nasal dimensions was seen in the anterior and middle parts of the nose, however, significant changes were also seen in the posterior nasal cavity and post nasal space. There are a number of possible sources of artefact. First, confusion of the first and second minima may produce apparent movement of the minimum cross-sectional area following nasal decongestion. Second, a postulated change in the acoustic path length may lead to apparent changes in volume in certain regions of the nose. Third, a variable and uncontrollable degree of sound energy loss will occur into the opposite nasal cavity beyond the posterior border of the septum. An apparent increase in the dimensions of this region will be seen as the opposite cavity decongests. We feel that all users of the acoustic rhinometer need to be aware of these potential sources of artefact, and attention needs to be focused on an agreed definition of the components of the acoustic rhinometry trace.

Acoustics↗
PubMed1999

Headache after resection of acoustic neuroma.

Long-lasting severe headaches are reported to occur in up to 83% of patients who have undergone resection of acoustic neuroma, especially through a suboccipital approach. These headaches, however, are not well defined. The objective of this study was to assess the frequency and character of new-onset headaches after resection of acoustic neuroma by a suboccipital approach with cranioplasty. Review of the medical record was followed by a telephone interview with 48 patients (67% female; mean age, 52 years) who had undergone resection of an acoustic neuroma through a suboccipital craniotomy during the 2 years before the study. Of the 48 patients, 58% had post-operative head pain that lasted more than 7 days and could be categorized into two types. A moderate to severe, short-term head pain with gradual resolution occurred in 35% of the patients, and a mild, unremitting pain was reported by 23%. Both types of pain had a dull ache or pressure quality and were adjacent to or confined to the incisional area. Overall, 77% of the patients were pain-free within 4 months after operation. Age, sex, tumor size, or preoperative history of headache did not influence development of the postoperative pain. We found that new-onset headache after resection of acoustic neuroma by a suboccipital approach with cranioplasty is much less common than previously reported and is best described as mild incisional pain rather than a severe headache. The literature regarding headaches after different surgical approaches for acoustic neuroma resection is reviewed, and possible explanations for development of the pain are discussed.

Adult↗
PubMed1993

MRI of acoustic schwannoma: a retrospective study of 89 tumours.

Magnetic resonance imaging (MRI) is now considered the diagnostic study of choice for evaluation of patients with suspected acoustic schwannoma. This retrospective study of 118 MR examinations presents an analysis of the MR findings of 89 acoustic tumours in 86 patients. The method of examination included precontrast and gadolinium(Gd)-enhanced MRI in 72 and plain MRI in 14 patients. The common MR-appearances of acoustic schwannomas were: on T1-weighted images (WI) isointense (36%) or slightly hypointense (64%) relative to the brainstem; intense and homogeneous contrast enhancement in 62%; the shape of the tumour was round or oval in 71%; the tumour was centred at/or located in the internal auditory canal (IAC) in 80%. The small acoustic schwannomas were mostly round or oval in shape and showed homogeneous signal intensity (SI) both before and after Gd. The larger acoustic tumours were more heterogeneous in morphology and SI. The significance of these and other signs, early diagnosis and differential diagnosis are discussed.

Adolescent↗
PubMed1992

Influence of spontaneous otoacoustic emissions (SOAE) on acoustic distortion product input/output functions: does the medial efferent system act differently in the vicinity of an SOAE?

Otoacoustic emission (OAE) generation mechanisms reside in the active micromechanical properties of the organ of Corti, and especially in the outer hair cells (OHCs). OHCs are strongly innervated by medial efferent olivo-cochlear fibres. Decrease of the intensity of transiently evoked otoacoustic emissions (TOAEs) and modification of spontaneous otoacoustic emissions (SOAEs) during acoustic stimulation of the contralateral ear have already been shown in humans. Similar results were obtained in guinea pigs with a decrease of 2F1-F2 acoustic distortion products (DPOAEs) and a suppression of the effect with sectioning of the floor of the fourth ventricle. The present study sought to investigate the influence of contralateral auditory stimulation on DPOAEs recorded in humans. It shows a decrease in DPOAE intensity for all frequencies, at levels above 45 dB SPL of contralateral broad band noise. This effect was found at levels of contralateral BBN well below the acoustic reflex threshold, and in subjects without acoustic reflex. Moreover, the influence of transcranial transmission could be ruled out since no effect was found when contralateral BBN applied to the altered ear of totally unilaterally deaf patients. Thus, the contralateral acoustic stimulation effect on DPOAEs provides a new means of functional exploration of the medial efferent system in humans. The effect obtained is more ample at low primary frequency levels. Moreover, as DPOAEs are known to be stronger and to show more irregular input/output function patterns in the vicinity of an SOAE, the influence of contralateral auditory stimulation was studied for DPOAEs recorded at 10 Hz, 50 Hz and 150 Hz from an SOAE frequency.

Acoustic Stimulation↗
PubMed2001

Can maximum comfortable loudness levels in hearing impaired listeners be predicted from ipsilateral acoustic reflex thresholds recorded with high frequency probes?

This study was designed to test the effectiveness of the ipsilateral acoustic reflex thresholds measured with low and high frequency probes in predicting the maximum comfortable loudness levels (MaxCLs) in hearing-impaired subjects using recently available sophisticated procedures for acoustic reflex and loudness measures. Loudness growth functions were measured in hearing-impaired subjects at .5, 1 and 2 kHz using a computerized procedure. The maximum level among those sound pressure levels judged as 'comfortable' was designated as the MaxCL. Acoustic reflex thresholds were measured for .5, 1 and 2 kHz activator signals using 226, 678 and 1000 Hz probes. Regression analyses suggested that acoustic reflex thresholds recorded with the 678 and 1000 Hz probes could provide an objective estimate of the MaxCLs for 1 and 2 kHz. Thus, acoustic reflex thresholds may be useful in fitting hearing aids for those subjects in whom reliable measures of MaxCLs cannot be obtained.

Adult↗
PubMed2006

Optimal dose of stereotactic radiosurgery for acoustic neuromas: A systematic review.

Radiosurgery is increasingly employed in the treatment of acoustic neuroma, but the optimal dose in terms of long-term tumour control and minimal adverse effects has not been established. We performed a systematic review of the published literature of radiosurgery of acoustic neuroma to assess whether the use of low dose radiosurgery is as effective as high dose treatment. Reports of radiosurgery for acoustic neuroma were identified through a Medline search. Studies with at least 15 patients and a median follow-up longer than 12 months were included. The relationship between actuarial 5-year progression-free survival (PFS), and tumour and treatment parameters was examined. Forty-two studies were included. Tumour control following lower radiosurgery doses was similar to that reported following high doses. Only 12 studies reported actuarial outcomes at 5 years. There was no relationship between PFS at 5 years and dose to the tumour margin. Radiosurgery of larger tumours was associated with lower 5 year PFS (p < 0.05). Although on initial inspection radiosurgery of acoustic neuroma with doses of 12 - 13 Gy seems to be as effective as higher dose treatment, the available reports are subject to a number of confounding factors, are not sufficiently statistically powered and there is only limited long-term actuarial outcome data. Currently, available studies do not provide sufficient confidence to support the claim that low dose radiosurgery is equally effective as higher doses in the long-term control of acoustic neuroma.

Adolescent↗
PubMed2006

Diagnostic value of voice acoustic analysis in assessment of occupational voice pathologies in teachers.

It has been shown that teachers are at risk of developing occupational dysphonia, which accounts for over 25% of all occupational diseases diagnosed in Poland. The most frequently used method of diagnosing voice diseases is videostroboscopy. However, to facilitate objective evaluation of voice efficiency as well as medical certification of occupational voice disorders, it is crucial to implement quantitative methods of voice assessment, particularly voice acoustic analysis. The aim of the study was to assess the results of acoustic analysis in 66 female teachers (aged 40-64 years), including 35 subjects with occupational voice pathologies (e.g., vocal nodules) and 31 subjects with functional dysphonia. The acoustic analysis was performed using the IRIS software, before and after a 30-minute vocal loading test. All participants were subjected also to laryngological and videostroboscopic examinations. After the vocal effort, the acoustic parameters displayed statistically significant abnormalities, mostly lowered fundamental frequency (Fo) and incorrect values of shimmer and noise to harmonic ratio. To conclude, quantitative voice acoustic analysis using the IRIS software seems to be an effective complement to voice examinations, which is particularly helpful in diagnosing occupational dysphonia.

Adult↗