Maxakalí Nasality and Field Recording with Earbud Microphony

As dificuldades em se verificar acusticamente a nasalização de vogais são bem conhecidas e por isso diversos pesquisadores optam por usar máscaras de fluxo nasal. Porém, esse tipo de equipamento nem sempre é prático para gravações em campo. No presente estudo, foi aplicada a tecnologia recentemente desenvolvida de gravação com fones de ouvido apresentada em Stewart e Kohlberger (2017), com o intuito de estudar a nasalidade no Maxakalí e esse processo de gravação como um novo método de fonologia experimental em campo. A língua Maxakalí conta com diversos fenômenos ligados à nasalidade como, por exemplo, espraiamento de nasalidade, pré-nasalização em início de palavra, entre outros. Um objetivo ao usar uma metodologia com equipamentos de baixo custo é facilitar a geração de uma representação visual do perfil nasal de uma palavra, produzindo possibilidades para a linguística experimental mostrar uma integração maior com a pedagogia de língua

A comparative analysis of swallowing accelerometry and sounds during saliva swallows

Background: Accelerometry (the measurement of vibrations) and auscultation (the measurement of sounds) are both non-invasive techniques that have been explored for their potential to detect abnormalities in swallowing. The differences between these techniques and the information they capture about swallowing have not previously been explored in a direct comparison. Methods: In this study, we investigated the differences between dual-axis swallowing accelerometry and swallowing sounds by recording data from adult participants and calculating a number of time and frequency domain features. During the experiment, 55 participants (ages 18-65) were asked to complete five saliva swallows in a neutral head position. The resulting data was processed using previously designed techniques including wavelet denoising, spline filtering, and fuzzy means segmentation. The pre-processed signals were then used to calculate 9 time, frequency, and time-frequency domain features for each independent signal. Wilcoxon signed-rank and Wilcoxon rank-sum tests were utilized to compare feature values across transducers and patient demographics, respectively. Results: In addition to finding a number of features that varied between male and female participants, our statistical analysis determined that the majority of our chosen features were statistically significantly different across the two sensor methods and that the dependence on within-subject factors varied with the transducer type. However, a regression analysis showed that age accounted for an insignificant amount of variation in our signals. Conclusions: We conclude that swallowing accelerometry and swallowing sounds provide different information about deglutition despite utilizing similar transduction methods. This contradicts past assumptions in the field and necessitates the development of separate analysis and processing techniques for swallowing sounds and vibrations

Age, Sex, and Head Position Effects on Swallowing Accelerometry and Sounds

Accelerometry (the measurement of vibrations) and auscultation (the measurement of sounds) are both noninvasive techniques that have been explored for detecting abnormalities in swallowing. The differences between these techniques and the information they capture about swallowing have not previously been explored in a direct comparison. In this study, we investigated the differences between dual-axis swallowing accelerometry and swallowing sounds by recording data from adult participants and calculating a number of time and frequency domain features. During the experiment, 55 participants (ages 18-65) were asked to complete five saliva swallows with a neutral head position and then five saliva swallows in a 'chin-tuck' position. The resulting data was processed by previously designed techniques utilizing wavelet denoising, spline filtering, and fuzzy means segmentation. The pre-processed signals were then used to calculate nine time, frequency, and time-frequency domain features for each independent signal. In addition to finding a number of features that varied with the participant's age, sex, and head position, our statistical analysis determined that the majority of our chosen features were significantly different for different transducers. We conclude that swallowing accelerometry and swallowing sounds provide different information about deglutition despite utilizing similar transduction methods

Comparison of nasalance measurements from accelerometers and microphones and preliminary development of novel features

This study compares four nasalance measures computed as ratios between the amplitude of signals recorded with accelerometers and microphones. Two new measures based on RMS amplitude differences between the nasal signal and either the vocal folds vibration signal (LND) or the oral acoustic signal (OND) are introduced. Measures were compared on a total of 584 utterances produced by four native French speakers. Results show that (1) all measures separate nasal from oral consonants, (2) the different experimental setups cannot be considered equivalent, (3) difference-based measures appear to better describe the time course of nasality than ratio-based measures. Index Terms: nasality, nasalance, accelerometer, microphone 1