Electromagnetic Articulometry (EMA)
We have acquired two 3D Electromagnetic Articulographs (EMA; the model is AG 501, manufactured by Carstens). Each system has excellent temporal resolution (1250 samples per second) which allows us to track the movement of articulators in a precise manner. With two systems the articulatory movements of two speakers can be tracked simultaneously. This makes it possible to examine, for example, speech accommodation and speech production in dialogue.
Articulatory Research: Ultrasound Imaging
We have recently acquired a Zonare scan engine ultrasound device for performing research and data collection on the surface of the tongue. The ultrasound unit can be docked (as shown) on the cart, or removed for in-class demonstrations.
The unit can also be connected to a computer using a frame grabber device (an Epiphan DVI2USB) for direct and automated data collection. The device is sufficiently portable and compact to be taken into the field for articulatory research.
The SQLab EVA2 pneumotachograph measures oral and nasal airflow by measuring air pressure differences during continuous speech. Oral airflow is captured by a pliant silicone mask that forms a seal around the mouth. Nasal airflow is captured by tube(s) placed at the entrance of the speaker’s nostrils.
In this system, air passes through a mesh screen, and pressure transducers measure the pressure drop across the screen. Because airflow equals pressure divided by the impedance of the pathway, and the impedance of the mesh screen is known, airflow can be calculated directly. Intra-oral and sub-glottal air pressure can also be measured through the creative use of catheters.
Airflow and high-quality audio are captured simultaneously, and are automatically synchronized by specialized software (running on a dedicated PC workstation) that also applies a smoothing algorithm to the airflow traces.
The Glottal Enterprises EG2-PCX electroglottograph is a non-invasive tool for measuring vocal fold vibration. A speaker wears a neck strap holding a pair of electrodes in place around the glottis (LED indicators on the EGG allow for precise location of the electrodes). The system then sends a low-voltage, high frequency current between the electrodes (two separate currents between the upper and lower halves of each electrode) and reads changes in electrical impedance across the vocal folds as opening (high impedance) and closing (low impedance). The result is a wav file that can be read in any standard software. Please see our video: configuring the EGG and collecting time-aligned EGG and audio signals with Audacity
With the EGG and a microphone you can also amaze and impress your friends and family by measuring precisely how far the microphone was from the speaker’s vocal folds at the time of recording.
Perceptual and Acoustic Research:
IAC Sound Booth
Our 10′ x 10′ IAC sound attenuated booth is located in 400 Lorch Hall. The booth is large enough to support four concurrent participants in a perception experiment and features a custom pass-thru port to allow simultaneous ultrasound imaging and high quality audio recordings. The booth is generally configured for quick audio recording so a researcher can display prompts or a word list on the consultant’s digital display while isolating the recording/controlling computer from the microphone.
The newest addition to our speech perception lab is a state-of-the-art EyeLink 1000+ Remote Eye Tracking system. This system measures, via a desk-mounted camera, participant's eye movements to images on a computer screen as the acoustic speech signal unfolds. The excellent temporal resolution of this system (up to 1000 samples per second) allows us to study the time course of speech perception. Faculty and students are currently testing hypotheses about the use of coarticulatory and social information in participant's moment-by-moment processing of speech.
Perceptual testing is a primary focus of our laboratory. Our facilities include four macbook computers; four Cedrus response boxes; low latency keyboards; SuperLab, e-Prime, and Linger software; and an array of small but necessary devices: AKG circumaural headphones, edirol USB audio interfaces, mixing boards, pre-amps, etc.