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Low power, radarlike electromagnetic (EM) wave sensors, operating in a homodyne interferometric mode, are being used to measure tissue motions in the human vocal tract during speech. However, when these and similar sensors are used in front of the laryngeal region during voiced speech, there remains an uncertainty regarding the contributions to the sensor signal from vocal fold movements versus those from pressure induced trachea-wall movements. Several signal-source hypotheses are tested by performing experiments with a subject who had undergone tracheostomy, and who still was able to phonate when her stoma was covered (e.g., with a plastic plate). Laser-doppler motion-measurements of the subject's posterior trachea show small tissue movements, about 15 microns, that do not contribute significantly to signals from presently used EM sensors. However, signals from the anterior wall do contribute. EM sensor and air-pressure measurements, together with 3-D EM wave simulations, show that EM sensors measure movements of the vocal folds very well. The simulations show a surprisingly effective guiding of EM waves across the vocal fold membrane, which, upon glottal opening, are interrupted and reflected. These measurements are important for EM sensor applications to speech signal de-noising, vocoding, speech recognition, and diagnostics.

Measurements of the neck frequency response function (NFRF), defined as the ratio of the spectrum of the estimated volume velocity that excites the vocal tract to the spectrum of the acceleration delivered to the neck wall, were made at three different positions on the necks of nine laryngectomized subjects (five males and four females) and four normal laryngeal speakers (two males and two females). A minishaker driven by broadband noise provided excitation to the necks of subjects as they configured their vocal tracts to mimic the production of the vowels /a/, /ae/, and /I/. The sound pressure at the lips was measured with a microphone and an impedance head mounted on the shaker measured the acceleration. The neck wall passed low-frequency sound energy better than high-frequency sound energy, and thus the NFRF was accurately modeled as a low-pass filter. The NFRFs of the different subject groups (female laryngeal, male laryngeal speakers, laryngectomized males, and laryngectomized females) differed from each other in terms of corner frequency and gain, with both types of male subjects presenting NFRFs with larger overall gains. In addition, there was a notable amount of intersubject variability within groups. Because the NFRF is an estimate of how sound energy passes through the neck wall, these results should aid in the design of improved neck-type electrolarynx devices.

During clinical voice assessment, laryngologists and speech-language pathologists rely heavily on laryngeal endoscopy with videostroboscopy to evaluate pathology and dysfunction of the vocal folds. The cost effectiveness, ease of use, and synchronized audio and visual feedback provided by videostroboscopic assessment serve to maintain its predominant clinical role in laryngeal imaging. However, significant drawbacks include only two-dimensional spatial imaging and the lack of subsurface morphological information. A novel endoscope will be presented that integrates optical coherence tomography that is spatially and temporally co-registered with laryngeal videoendoscopic technology through a common path probe. Optical coherence tomography is a non-contact, micron-resolution imaging technology that acts as a visual ultrasound that employs a scanning laser to measure reflectance properties at air-tissue and tissue-tissue boundaries. Results obtained from excised larynx experiments demonstrate enhanced visuali...

The subglottal pressure contour Ps for speech is considered to have three phases: initiation (rapid rise), working (level or slightly declining), and termination (rapid fall). The current work focuses on characterization of the working phase in terms of the distribution of pitch accents and of phrase and boundary tones. In particular, the degree of Ps declination is studied. A measure of Ps declination has proven difficult to define [cf. Strik and Boves, J. Phonetics 23, 203–220 (1995)]. Therefore, in pilot work, subjective ratings of degree of declination are made on a subset of a corpus in which the tone distribution is controlled. Significant variation in the degree of declination is observed among speakers. For example, Ps for one speaker is relatively constant to slightly declining, while for another it is almost always sharply declining. For some speakers utterances with an early‐occurring nuclear pitch accent (NPA) show greater degree of declination than utterances with a late‐occurring NPA, as do ...

Subglottal pressure (Ps) contours for speech are described as having three phases: initial rise, constant or declining working phase, and final fall. The current work is part of a project to relate characteristics of the Ps contour to prosodic events. To that end, one must identify the three phases in a Ps contour. In past work, it was found that the initial phase is relatively easy to identify, but the transition from the working phase to final fall is less clear [J. Slifka (2000)]. Confounding issues could include segmental impedance, pitch accents, and phrase and boundary tones, all of which can have local effects on Ps. In this work, it is attempted to control tones and segments at the ends of utterances in order to better identify final fall. Lung pressure is estimated from esophageal pressure (corrected for lung volume). Pilot data from one subject indicate that the beginning of final fall is easier to identify when the phrase and boundary tones are low than when they are high. Results will be prese...

EM wave sensors are being used to measure human vocal tract movements during voiced speech. However, when used in the glottal region there remains uncertainty regarding the contributions to the sensor signal from the vocal fold opening and closing versus those from pressure induced trachea–wall movements. Several signal source hypotheses were tested on a subject who had undergone tracheostomy 4 years ago as a consequence of laryngeal paresis. Measurements of vocal fold and tracheal wall motions were made using an EM sensor, a laser‐Doppler velocimeter, and an electroglottograph. Simultaneous acoustic data came from a subglottal pressure sensor and a microphone at the lips. Extensive 3‐D numerical simulations of EM wave propagation into the neck were performed in order to estimate the amplitude and phase of the reflected EM waves from the 2 different sources. The simulations and experiments show that these sensors measure, depending upon location, both the opening and closing of the vocal folds and the mov...

Dynamic sequences of magnetic resonance images (MRI) of the vocal tract were obtained with a frame rate of 144 frames/second. Changes in vertical position and length of the vocal folds, both observable in the mid‐sagittal plane, have been argued to play a role in consonant production in addition to their primary function in the control of vocal fundamental frequency (F0) [W. G. Ewan and R. Krones, J. Phonet. 2, 327–335 (1974); A. Lofqvist et al., Haskins Lab. Status Report Speech Res., SR‐97/98, pp. 25–40, 1989], but temporal resolution of available techniques has hindered direct imaging of these articulations. A novel data acquisition sequence was used to circumvent the imaging time imposed by standard MRI (typically 100–500 ms). Images were constructed by having subjects rhythmically repeat short utterances 256 times using the same F0 contour. Sixty‐four lines of MR data were sampled during each repetition, at 7 millisecond increments, yielding partial raw data sets for 64 time points. After all repetitions were completed, one frame per time point was constructed by combining raw data from the corresponding time point during every repetition. Preliminary results indicate vocal fold shortening and lowering only during voiced consonants and in production of lower F0.