Browsing by Author "Somanath, Keerthan"
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Item Automated Analysis of Electroglottographic Signal in Adductor Spasmodic Dysphonia(2013-01-22) Somanath, Keerthan; Mau, TedINTRODUCTION: The human voice can be evaluated by a variety of methods. Electroglottographic (EGG) signal is produced when vocal fold vibrations produce cyclic fluctuation in the electrical impedance across the larynx. The EGG signal thus reflects the degree of contact between the vocal folds during voice production and provides a measure of voice quality based on phonatory physiology. However, the utility of EGG has been limited because existing methods of EGG signal analysis focus on the evaluation of 2-3 parameters in a segment of sustained vowel production, which does not reflect pathologies more apparent in conversational speech. We hypothesize that the EGG signal can capture perceptually relevant information from continuous speech in adductor spasmodic dysphonia (ADSD), an enigmatic speech disorder. OBJECTIVES: 1. To develop an automated computer algorithm to analyze the EGG signal in continuous dysphonic speech. 2. To identify EGG waveform features that correlate with the perceived quality of vocal strain in ADSD. METHODS: A computer program was created and refined in MATLAB to display and analyze EGG data via a graphical user interface (GUI). An automated peak-detection algorithm was developed using the differentiated EGG signal and used to perform simultaneous multi-parameter analysis on the EGG signal from normal speech and speech in patients with ADSD. Between-group comparisons were made using two-tailed Student's t test. Also, intrasubject comparison was made between strained and less-strained syllables in ADSD speech. RESULTS: A program was successfully written to allow the display and automated analysis of EGG data from samples of continuous dysphonic speech. The program was found to generate data with good internal consistency. Application to normal and ADSD subjects showed that the open quotient parameter was able to distinguish between strained and less-strained syllables with statistical significance (p=0.04). DISCUSSION/CONCLUSION: We have developed a method to analyze EGG signal from samples of continuous dysphonic speech. The numerical and graphical data obtained support the utility of EGG as an objective means to clinically highlight the speech differences between normal subjects and subjects with ADSD. Further testing to establish normative values for the analyzed EGG parameters and their subsequent comparison with patient EGG data is required to affirm their utility for routine clinical voice assessment.Item Quantifying the Perceptual Quality of Strain: An Electroglottographic Analysis of Continuous Dysphonic Speech(2015-04-03) Somanath, Keerthan; Mau, TedINTRODUCTION: Excessive vocal effort perceived as strain may involve increased vocal fold compression. Electroglottography (EGG) in principle could provide a measure of strain directly connected to oscillatory kinematics at the sound source. The utility of EGG has been limited by considerable inter- and intra-subject variability. OBJECTIVE: This work aims to (1) develop an algorithm to analyze EGG signal in continuous, dysphonic speech and (2) identify parameters that correlate with strain. METHODS: EGG signal from 8 normal speakers and 8 subjects with adductor spasmodic dysphonia (ADSD) reading two-sentence excerpts from the Rainbow Passage was processed by the new software developed in MATLAB. The contact quotient (CQ), pulse width at the 50% amplitude level (EGGW50), and various closing slope and opening slope measures were extracted from selected speech segments. Intra-subject and inter-subject comparisons were then made. RESULTS: None of the EGG parameters differed between normal and ADSD speakers. Within- subject comparison among ADSD speakers showed that the opening slope measure SO7525 distinguished between the strained and unstrained syllables. CONCLUSION: These results provide further insight into the utility and limitations of EGG. While EGG may have limited utility in inter-subject comparison, it may provide a useful objective measure of vocal strain in the same subject with variable degrees of strain or over time.