Anna Barney

Fluid flow in a dynamic mechanical model of the vocal folds and tract. I. Measurements and theory

In this study, aerodynamic and acoustic measurements were obtained in a dynamic mechanical model of the larynx and vocal tract. The model consisted of a uniform duct, intersected by a pair of sinusoidally oscillating shutters. A controlled airflow along the duct was periodically disturbed by the action of the shutters and pressure, and flow velocity measurements were obtained in the region downstream. The velocity field in the duct could be decomposed into three distinct components: a mean flow, a fluctuating acoustic particle velocity, and a fluctuating nonacoustic velocity associated with the transport of vortices along the duct at the local mean flow velocity. Two theoretical models for sound radiation from the duct exit were investigated. The first was based on the in-duct acoustic field alone and was unable to provide a realistic prediction of the measured, radiated sound field except at the first formant of the duct. In the second a simple description of sound generation due to the interaction of vo...

Fluid flow in a dynamic mechanical model of the vocal folds and tract. II. Implications for speech production studies

A companion paper [Barney et al., J. Acoust. Soc. Am. 105, 444–455 (1999)] presents measurements in a dynamic mechanical model (the DMM) of the vocal folds and vocal tract: It was shown that closer prediction of the radiated sound pressure was possible when nonacoustic (vortical) as well as acoustic components of the velocity in the duct were included. In this paper, using such a simple geometry to model the vocal tract is justified by comparing acoustic and aerodynamic measurements in the DMM to those made in vivo: sub- and supraglottal pressures, radiated pressure, and hot wire velocities. The DMM produces sound equivalent to weak, low-frequency falsetto. A Rothenberg mask was then placed on the end of the DMM, and two estimates of the glottal waveform were compared to velocities measured near the “glottis.” The results show that the glottal waveform does not resemble any hot wire velocities measured near the shutters; travel times for acoustic and nonacoustic components of the velocity field differ sig...

Clinically useful outcome measures for physiotherapy airway clearance techniques: a review

Abstract A lack of good outcome measures has been a barrier to the development of an evidence base for all areas of respiratory physiotherapy. Many of the clinically available outcome measures are not specifically related to the physiotherapy intervention employed and may be affected by other factors. In this paper, the outcome measures currently clinically available to UK NHS physiotherapists to assess the response to alveolar recruitment and airway clearance interventions have been reviewed. It is clear that there is an urgent need to increase the accuracy, reliability, and sensitivity of the outcome measures employed, or to develop new measures to assess the effectiveness of respiratory physiotherapy. Lung sounds provide useful, specific information, but standard auscultation is too subjective to allow them to be used as an outcome measure. Computer Aided Lung Sound Analysis (CALSA) is proposed as a new objective, non-invasive, bedside clinical measure with the potential to monitor and assess the effects of airway clearance therapy.

In vitro experimental investigation of voice production.

The process of human phonation involves a complex interaction between the physical domains of structural dynamics, fluid flow, and acoustic sound production and radiation. Given the high degree of nonlinearity of these processes, even small anatomical or physiological disturbances can significantly affect the voice signal. In the worst cases, patients can lose their voice and hence the normal mode of speech communication. To improve medical therapies and surgical techniques it is very important to understand better the physics of the human phonation process. Due to the limited experimental access to the human larynx, alternative strategies, including artificial vocal folds, have been developed. The following review gives an overview of experimental investigations of artificial vocal folds within the last 30 years. The models are sorted into three groups: static models, externally driven models, and self-oscillating models. The focus is on the different models of the human vocal folds and on the ways in which they have been applied.

Articulatory capacity of Neanderthals, a very recent and human-like fossil hominin

Scientists seek to use fossil and archaeological evidence to constrain models of the coevolution of human language and tool use. We focus on Neanderthals, for whom indirect evidence from tool use and ancient DNA appears consistent with an adaptation to complex vocal-auditory communication. We summarize existing arguments that the articulatory apparatus for speech had not yet come under intense positive selection pressure in Neanderthals, and we outline some recent evidence and analyses that challenge such arguments. We then provide new anatomical results from our own attempt to reconstruct vocal tract (VT) morphology in Neanderthals, and document our simulations of the acoustic and articulatory potential of this reconstructed Neanderthal VT. Our purpose in this paper is not to polarize debate about whether or not Neanderthals were human-like in all relevant respects, but to contribute to the development of methods that can be used to make further incremental advances in our understanding of the evolution of speech based on fossil and archaeological evidence.

Are crackles an appropriate outcome measure for airway clearance therapy

BACKGROUND: There is an urgent need to develop new outcome measures for respiratory therapy, to evaluate its effectiveness. Adventitious sounds generated from the lungs (crackles and wheezes), can now be quantified and characterized objectively with computer technology. To our knowledge, this is the first reported study designed to assess any change in lung crackles before and after a single session of airway clearance therapy. METHODS: Twenty-three stable bronchiectasis patients were recruited from United Kingdom out-patient clinics and treated with a single session of airway clearance therapy, using the active cycle of breathing technique. Sound recordings were made before and after the session at 7 anatomical chest locations. Computerized lung sound analysis was used to measure crackle parameters: 2-cycle deflection width (2CD), and crackle number per breath cycle (nBC). Perceived breathlessness, lung function, and oxygen saturation data were also recorded. RESULTS: Crackle mean 2CD and mean nBC increased post intervention. Sixteen participants (70%) showed a statistically significant difference in mean crackle 2CD before and after the session at ≥ 1 chest location. Thirteen (57%) participants had a difference between mean crackle 2CD before and after the intervention > 1 Smallest Real Difference (SRD, mean SRD = 2.23 ms) at ≥ 1 chest location. Differences in mean crackle nBC before and after the intervention did not exceed the SRD (mean SRD = 32 crackles per breath cycle) in any participant. Perceived breathlessness was significantly reduced post intervention; no significant changes were observed in either lung function or oxygen saturation. CONCLUSIONS: Crackle duration (2CD) was found to change after a single session of airway clearance therapy, and shows promise as a new outcome measure for respiratory therapy interventions.

Weak voicing in fricative production

Understanding of the production mechanisms of voiced fricatives lags significantly behind that of other phonemic categories of speech. This paper presents a new voicing classification criterion to distinguish the voicing in fricatives from that of their contextual vowels in VCV tokens: weak vs strong voicing. The criterion is based on the oral airflow, distinguishing it from previous criteria based jointly on the acoustic and EGG signals. Aerodynamic and EGG recordings of four normal adult speakers (two females and two males), producing a speech corpus of 9 isolated words with the European Portuguese (EP) voiced fricatives /v, z, ?/ in word-initial, -medial and -final position, and the same 9 words embedded in 42 different real EP carrier sentences, were analysed. Fricatives were characterised in terms of oral airflow, fundamental frequency, first formant intensity level and glottal open quotient in absolute terms and relative to the values found in their surrounding vowels. The voicing during fricative production presented properties distinct from the voicing of the contextual vowels, leading to the development of a classification criterion based on the relative amplitude of the oscillations in the oral airflow signal. This contributes to distinguish voicing in fricatives from the modal voicing of the vowels

Aerodynamic measures of speech in unilateral vocal fold paralysis (UVFP) patients

Abstract This paper reports the recording and analysis of an aerodynamic database of 51 words produced by four patients with unilateral vocal fold paralysis. The vowel–fricative–vowel boundaries were manually annotated, and the mean absolute oral airflow amplitude (OA), fundamental frequency (f0), and first formant intensity (IF1) were extracted from a 20 ms window in the steady state of each phone. A case study approach to analysis of phonatory behaviour for the subjects is presented. Significant differences were found between the absolute OA and IF1 for different phones. Large between-subject variations in absolute measures for OA and f0 were found. Relative values calculated from the difference in these parameters between phones show consistency for subjects of the same gender.

Evaluation of the agreement of tidal breathing parameters measured simultaneously using pneumotachography and structured light plethysmography

Structured light plethysmography (SLP) is a noncontact, noninvasive, respiratory measurement technique, which uses a structured pattern of light and two cameras to track displacement of the thoraco–abdominal wall during tidal breathing. The primary objective of this study was to examine agreement between tidal breathing parameters measured simultaneously for 45 sec using pneumotachography and SLP in a group of 20 participants with a range of respiratory patterns (“primary cohort”). To examine repeatability of the agreement, an additional 21 healthy subjects (“repeatability cohort”) were measured twice during resting breathing and once during increased respiratory rate (RR). Breath‐by‐breath and averaged RR, inspiratory time (tI), expiratory time (tE), total breath time (tTot), tI/tE, tI/tTot, and IE50 (inspiratory to expiratory flow measured at 50% of tidal volume) were calculated. Bland–Altman plots were used to assess the agreement. In the primary cohort, breath‐by‐breath agreement for RR was ±1.44 breaths per minute (brpm). tI, tE, and tTot agreed to ±0.22, ±0.29, and ±0.32 sec, respectively, and tI/tE, tI/tTot, and IE50/IE50SLP to ±0.16, ±0.05, and ±0.55, respectively. When averaged, agreement for RR was ±0.19 brpm. tI, tE, and tTot were within ±0.16, ±0.16, and ±0.07 sec, respectively, and tI/tE, tI/tTot, and IE50 were within ±0.09, ±0.03, and ±0.25, respectively. A comparison of resting breathing demonstrated that breath‐by‐breath and averaged agreements for all seven parameters were repeatable (P > 0.05). With increased RR, agreement improved for tI, tE, and tTot (P ≤ 0.01), did not differ for tI/tE, tI/tTot, and IE50 (P > 0.05) and reduced for breath‐by‐breath (P < 0.05) but not averaged RR (P > 0.05).

A model of breathing abnormalities in sleep for development of classification and diagnosis techniques

Following the recognition of the obstructive sleep apnoea (OSA) disease, snoring achieved a completely new status from being a mere social problem to an important clinical disorder. Using modern signal analysis equipment and software enables breath-by-breath investigation of snoring and opens possibilities for automatic detection of specific acoustic events. The simulation model proposed in this study provides a repeat-able test-bed for signal processing techniques that are under development to aid clinical diagnosis of underlying pathological problems and to identify periods of sleep apnea that may develop into more serious conditions. Noise and artifacts can be added to the simulated data for assessment of algorithm robustness prior to application to clinical data that is being recorded non-invasively and remotely.