Transducer effect on ASR applications over the telephone network

Potential applications of automatic speech recognition (ASR) technology over the telephone network that involve multiple telephone handsets as input transducers to recognition systems are discussed. A series of performance assessments was conducted with two matched databases, one created over a conventional high-quality dynamic microphone and one over a set of standard telephones. The experiments were conducted in the context of small vocabulary speaker-dependent isolated word recognition. The procedure used to collect the two databases and the technique employed in the experiments made it possible to distinguish telephone handset related recognition errors from those caused by other variables. The results, derived from a total of 264264 testing utterances, suggest that transducer variability generally degrades the overall system performance across speakers, but its impact on recognition accuracy relative to other variables such as across-speaker variability and within-speaker variability is considerably smaller