Reliability of the Language ENvironment Analysis system (LENA™) in European French

Abstract

In this study, we examined the accuracy of the Language ENvironment Analysis (LENA) system in European French. LENA is a digital recording device with software that facilitates the collection and analysis of audio recordings from young children, providing automated measures of the speech overheard and produced by the child. Eighteen native French-speaking children, who were divided into six age groups ranging from 3 to 48 months old, were recorded about 10-16 h per day, three days a week. A total of 324 samples (six 10-min chunks of recordings) were selected and then transcribed according to the CHAT format. Simple and mixed linear models between the LENA and human adult word count (AWC) and child vocalization count (CVC) estimates were performed, to determine to what extent the automatic and the human methods agreed. Both the AWC and CVC estimates were very reliable (r = .64 and .71, respectively) for the 324 samples. When controlling the random factors of participants and recordings, 1 h was sufficient to obtain a reliable sample. It was, however, found that two age groups (7-12 months and 13-18 months) had a significant effect on the AWC data and that the second day of recording had a significant effect on the CVC data. When noise-related factors were added to the model, only a significant effect of signal-tonoise ratio was found on the AWC data. All of these findings and their clinical implications are discussed, providing strong support for the reliability of LENA in French.Keywords Adult word count . Child vocalization count . Reliability . Human transcriber . European French . Automatic speech recognition technology . Signal-to-noise ratio Studies in child language acquisition and disorders generally require reliable audio recordings. Most of the time, these recordings are limited in duration since they must meet physical constraints. The main goal of the experimenter is to develop a data acquisition system that is non-invasive and also preserves the quality of the recordings. Whereas fixed recording systems can restrict the child's movements, mobile systems, usually placed on the child, may affect the quality of recordings by adding friction noises. Experimenters, as a result, have to rely upon their own ingenuity to acquire a sufficient amount of high-quality data. Still, the problems do not end there. Once the data collection stage has been completed, data processing remains a time-consuming and tedious task, even when performing simple word counts. Localization of the child's productions, versus those addressed by adults to the child, is mandatory before transcribing them and then analyzing their content. All these constraints are liable to limit the number of tested subjects, and hence the amount of data collected. To overcome these drawbacks, a system was launched in 2004 allowing for large-scale all-day audio recording and

The LENA System Applied to Swedish: Reliability of the Adult Word Count Estimate

“…As expected, the reliability of the AWC estimate in the LENA system when applied to Swedish was at the same general level as those found in other similar studies, albeit in the lower range and most similar to the French reliability result [16]. The present study differs from several of previous evaluations of the AWC measure in terms of how segments used for analysis were selected.…”

“…Similarly, in the Mandarin evaluation, a correlation of r=.73 between transcribed Shanghai dialect words and the estimated AWC was found [15]. When applying the LENA system to French however, the correlation between the system's AWC and human word count was somewhat lower (r = .64) [16]. The present study is the first to report an evaluation of the LENA system applied to Swedish.…”

“…The reliability of the AWC as estimated by the LENA system when applied to Swedish was found to be within the range of its reliability for Spanish, Mandarin and French [2,15,16], and most similar to its reliability for French [16]. Further evaluations of other estimates and different aspects of the LENA system are crucial for any language to which it is applied, in order for it to be used appropriately in research and clinical applications.…”

“…The present study differs from several of previous evaluations of the AWC measure in terms of how segments used for analysis were selected. In most previous evaluations, segments have been selected based on high amounts of adult and/or child speech (estimated either by the LENA system or by an unspecified estimation procedure) [11,15,16]. In the evaluation of LENA applied to Spanish [2], segment selection was based on the AWC estimate, but the selection procedure ensured segments with low AWC were included.…”

“…The LENA system has also been evaluated when applied to languages other than American English. The reliability of the AWC estimate specifically has so far been evaluated for Spanish, Mandarin and French [2,15,16]. In the evaluation of the AWC estimate of the LENA system applied to Spanish, 60 minutes out of ten recordings were transcribed, and the words in the transcription counted.…”