Section: New Results

Learnability relevant descriptions of linguistic corpora

Evidently, infants are acquiring their language based on whatever linguistic input is available around them. The extent of variation that can be found across languages, cultures and socio-economic background provides strong constraints (lower bounds on data, higher bounds on noise, and variation and ambiguity) for language learning algorithms.

• In [60], we provide an estimation of how frequently, and from whom, children aged 0-11 years (Ns between 9 and 24) receive one-on-one verbal input among Tsimane forager-horticulturalists of lowland Bolivia. Analyses of systematic daytime behavioral observations reveal $<$ 1 min per daylight hour is spent talking to children younger than 4 years of age, which is 4 times less than estimates for others present at the same time and place. Adults provide a majority of the input at 0–3 years of age but not afterward. When integrated with previous work, these results reveal large cross-cultural variation in the linguistic experiences provided to young children. Consideration of more diverse human populations is necessary to build generalizable theories of language acquisition.

• In [69], we provide a new measure of how the acoustic realizations of a given phonetic segment are affected by coarticulation with the preceding and following phonetic context. While coarticulation has been extensively studied using descriptive phonetic measurements, little is known about the functional impact of coarticulation for speech processing, and in particular, learnability. Here, we use DTW-based similarity defined on raw acoustic features and ABX scores to derive a measure of the effect of coarticulation on phonetic discriminability. This measure does not rely on defining segment-specific phonetic cues (formants, duration, etc.) and can be applied systematically and automatically to any segment in large scale corpora. We illustrate our method using stimuli in English and Japanese. We replicate some well-known results, i.e., stronger anticipatory than perseveratory coarticulation and stronger coarticulation for lax/short vowels than for tense/long vowels. We then quantify for the first time the impact of coarticulation across different segment types (like vowels and consonants).