Investigators:
- H. Timothy Bunnell, PhD.
- Rhonda Walter, MD
Background
Each week, the hospital receives about five new referrals for speech and language evaluation. There is a significant wait before these children can be scheduled for a clinical assessment. If speech therapy is recommended, there may be an additional wait to begin therapy. Clearly, there is a substantial population of children who need speech therapeutic services. Better access to speech therapeutic services would benefit the hospital and its patients. Computer-based tools would facilitate the process of assessing speech and delivering speech therapy.
The STAR system, developed in the Speech Research Laboratory, is a prototype computer-based speech assessment and training tool that uses an animated Star character to interact with and encourage children in speech learning and production tasks. These tasks are incorporated into different games. The STAR character acts as a guide and motivator throughout these games. The system, when completed, will start with basic phoneme recognition tasks, and progress through phoneme production tasks, first in isolation, then in simple, and eventually more complex phonetic contexts, and finally in sentences. The long range goal for the STAR project is to combine the latest technologies involving believable animated agents, speech recognition, artificial intelligence, and speech synthesis to create a computer-based speech training tool that children find enjoyable and easy to work with.
What We’re Doing
Currently we are in the process of evaluating one of the games. The game is a simple speech production game in which a child is asked to produce words drawn from a minimal pair that contrast a phoneme to be trained with one the child has already achieved. For example, if a child produces /w/ correctly, but also substitutes /w/ for /r/, we would use the minimal pair "red" and "wed" as test words in the game. The game proceeds by asking the child to say one of the words, captures and analyzes the child's utterance to determine how closely it matches recognition models for both contrasting words, and gives feedback to the child in the form of a spoken response from the star character regarding the accuracy of the child's production. The game is being evaluated for its ability to effectively decrease the length of acquisition time for the sounds being trained. Children between four and seven years of age who had difficulty articulating the /r/ sound were recruited to participate in the evaluation study. Children in one group used STAR to train the /r/ sound. Children in another group played with STAR using sounds that they had already mastered (i.e., different sounds than the one that they were having difficulty with). All children in the study received three half-hour sessions with STAR each week in addition to one half-hour of conventional speech therapy provided by a Speech Language Pathologist who didn't know which group the children were in. Before and after each session with STAR, all children recorded a series of words designed to probe their pronunciation of a variety of phonemes including /r/. These probe words are being analyzed for the percentage of phonemes correctly pronounced over the course of the experiment and compared between the two groups. In addition, we plan to use the data recorded from all children as they pronounced the words presented to them during the STAR game to further improve our speech recognition models for children's speech.
The STAR program is required to recognize and rate children's utterances. Because so little work has been done with children's speech, this is an important area of research in our lab. In order to continue to make improvements in the speech recognition technology that this program uses, we are developing a database of voice recordings of normal, American-English speaking children between the ages of six and eight. The database will be used for analysis of typically-developing children's speech patterns.
Some of What We’ve Found
Preliminary analyses from the STAR evaluation study are encouraging. Calculations using data from the probe recordings have been completed for 10 of the subjects who have completed the experiment. The amount of improvement between the probe recordings at the beginning and those at the end of the study were compared. Children who used STAR to train on the /r/ sound improved an average of 22.7 percentage points over the course of the study. Other children who also played with STAR, but not for the /r/ sound that they were having trouble with, improved an average of only 14.6 percentage points. This preliminary pattern suggests that STAR may be effective for decreasing acquisition time for sounds being trained, but this impression needs to be supported with more data before any firm conclusions can be offered.
In the current phase of the project, we are preparing raw data from 18 subjects for analysis by collaborating Speech Language Pathologists (SLPs). Seventeen SLPs have been enlisted to listen to and rate the accuracy of the childrens pronunciations of the probe words, which were recorded before and after each half-hour session with STAR over the course of the experiment.