Willemijn Heeren

Perceptual development of phoneme contrasts : How sensitivity changes along acoustic dimensions that contrast phoneme categories

Listeners discriminate acoustic differences between phoneme categories at a higher level than similarly sized differences within phoneme categories. The question this paper aims to answer is how this pattern in perceptual sensitivity develops along an acoustic dimension that contrasts two non-native speech sounds: through acquired distinctiveness, through acquired similarity, or through a combination of the two. A pretest-training-post-test experiment was designed to study perceptual development directly, i.e., by including (i) a discrimination task to measure perceptual sensitivity, (ii) a transfer test to ensure language learning instead of stimulus learning, and (iii) a control group to exclude task repetition as an explanation of improvement. It is shown that the typical peak in perceptual sensitivity near a phoneme boundary that native listeners show is not found in relatively inexperienced language learners, despite their ability to classify a continuum in a nativelike way after short laboratory training. Experiment II indicates that a discrimination peak may be achieved by language learners, but only after much more language experience than short-term laboratory training can offer. Furthermore, reasons are given why classification improvement in the laboratory should not be taken as evidence for (i) increased discrimination of the newly learned phonemes and (ii) learning of phoneme representations.

Access to recorded interviews: A research agenda

Recorded interviews form a rich basis for scholarly inquiry. Examples include oral histories, community memory projects, and interviews conducted for broadcast media. Emerging technologies offer the potential to radically transform the way in which recorded interviews are made accessible, but this vision will demand substantial investments from a broad range of research communities. This article reviews the present state of practice for making recorded interviews available and the state-of-the-art for key component technologies. A large number of important research issues are identified, and from that set of issues, a coherent research agenda is proposed.

Perception of prosody in normal and whispered French

The current study explored perception of prosody in normal and whispered speech using a two-interval, two-alternative forced-choice psychophysical task where listeners discriminated between French noun phrases pronounced as declaratives or interrogatives. Stimuli were either presented between 50 and 8000 Hz or filtered into one of three broad frequency regions, corresponding to harmonic-resolvability regions for normal speech (resolved, partially resolved, unresolved harmonics). Normal speech was presented against a speech-shaped noise masker, whereas whispered speech was presented in quiet. The results showed that discrimination performance was differentially affected by filtering for normal and whispered speech, suggesting that cues to prosody differ between speech modes. For whispered speech, evidence was mainly derived from the high-frequency region, whereas for normal speech, evidence was mainly derived from the low-frequency (resolved harmonics) region. Modeling of the early stages of auditory processing confirmed that for whispered speech, perception of prosody was not based on temporal auditory cues and suggests that listeners may rely on place of excitation (spectral) cues that are, in contrast with suggestions made by earlier work, distributed across the spectrum.

Perceptual development of the Finnish /t-tː/ distinction in Dutch 12-year-old children: A training study

Abstract This paper addresses the issue of how perceptual sensitivity develops in child L2 learners along an acoustic dimension that contrasts two non-native speech sounds, and of how their language learning compares to that of adult learners, as investigated in Heeren and Schouten (2008) . A pretest–training–posttest design was used to tap into the learning process, and development was predicted to occur mainly through increased sensitivity in the newly trained category boundary region, i.e. acquired distinctiveness, rather than through a decrease in sensitivity within the new categories, i.e. acquired similarity. This prediction was borne out by both adult and 12-year-old learners of the Finnish quantity contrast, but changes remained small. Even though the manner and speed of learning were comparable between age groups, adults showed higher discrimination scores than children did.

Asking or Telling--Real-time Processing of Prosodically Distinguished Questions and Statements.

We introduce a targeted language game approach using the visual world, eye-movement paradigm to assess when and how certain intonational contours affect the interpretation of utterances. We created a computer-based card game in which elliptical utterances such as “Got a candy” occurred with a nuclear contour most consistent with a yes–no question (H* H-H%) or a statement (L* L-L%). In Experiment 1 we explored how such contours are integrated online. In Experiment 2 we studied the expectations listeners have for how intonational contours signal intentions: do these reflect linguistic categories or rapid adaptation to the paradigm? Prosody had an immediate effect on interpretation, as indexed by the pattern and timing of fixations. Moreover, the association between different contours and intentions was quite robust in the absence of clear syntactic cues to sentence type, and was not due to rapid adaptation. Prosody had immediate effects on interpretation even though there was a construction-based bias to interpret “got a” as a question. Taken together, we believe this paradigm will provide further insights into how intonational contours and their phonetic realization interact with other cues to sentence type in online comprehension.

Easy Listening: Spoken Document Retrieval in CHoral

Abstract Given the enormous backlog at audiovisual archives and the generally global level of item description, collection disclosure and item access are both at risk. At the same time, archival practice is seeking to evolve from the analogue to the digital world. CHoral investigates the role automatic annotation and search technology can play in improving disclosure and access of digitized spoken word collections during and after this transfer. The core business of the CHoral project is to design and build technology for spoken document retrieval for heritage collections. In this paper, we will argue that in addition to solving technological issues, closer attention is needed for the work-flow and daily practice at audiovisual archives on the one hand, and the state-of-the-art in technology on the other. Analysis of the interplay is needed to ensure that new developments are mutually beneficial and that continuing cooperation can indeed bring envisioned advancements.

Vocalic correlates of pitch in whispered versus normal speech

In whispered speech, the fundamental frequency is absent as a main cue to pitch. This study investigated how different pitch targets can acoustically be coded in whispered relative to normal speech. Secondary acoustic correlates that are found in normal speech may be preserved in whisper. Alternatively, whispering speakers may provide compensatory information. Compared to earlier studies, a more comprehensive set of acoustic correlates (duration, intensity, formants, center-of-gravity, spectral balance) and a larger set of materials were included. To elicit maximal acoustic differences among the low, mid, and high pitch targets, linguistic and semantic load were minimized: 12 native Dutch speakers produced the point vowels (/a, i, u/) in nonsense vowel-consonant-vowel targets (with C = {/s/, /f/}). Acoustic analyses showed that in addition to systematic changes in formants, which have been reported before, also center of gravity, spectral balance, and intensity varied with pitch target, both in whispered and normal speech. Some acoustic correlates differed more in whispered than in normal speech, suggesting that speakers can adopt a compensatory strategy when coding pitch in the speech mode lacking the main cue. Speakers furthermore varied in the extent to which particular correlates were used, and in the combination of correlates they altered systematically.

Perception of Pitch Changes in Hearing-Impaired Adults with Aided and Unaided Hearing Loss

Background: Pitch relates to the low frequency temporal content of sound, which mainly depends on phase coding at the level of the auditory nerve. In this study, we aim to assess the detectibility of pitch changes in different populations of hearingimpaired subjects suffering from sensorineural hearing loss in order to identify possible poor temporal coding. Material and Methods: A number of tests – part of the A§E (ASSE or Auditory Speech Sounds Evaluation) psychoacoustic test suite – were used to assess the perception of pitch changes in adults with a hearing loss (a) in the high frequencies with or without classical hearing aids, (b) in the low frequencies, and (c) in a group of cochlear implant users. All test stimuli were controlled for their fundamental frequency (F0), which either remained stable during the stimulus presentation or which, simulating intonation, glided from F0 to F0+∆. Isolated synthetic complexes were used as well as pseudo-words or pseudosentences mimicking linguistically relevant contexts. The subjects were asked to distinguish these sounds in either identification or discrimination tasks. Results: Hearing-impaired subjects, and particularly those with low-frequency hearing loss, performed significantly worse in comparison to hearing adults on all tests. The use of a hearing aid did not yield significant improvements. The cochlear implant users experienced great difficulty in performing the tests. Conclusion: The intonation tests of A§E2009 are a useful diagnostic tool to distinguish hearing-impaired subjects based on their capacity to process low-frequency information. The tests may be of particular use in the evaluation of the impact of auditory rehabilitation, hearing aids, or electro-acoustic stimulation.

Coding pitch differences in voiceless fricatives: Whispered relative to normal speech

Intonation can be perceived in whispered speech despite the absence of the fundamental frequency. In the past, acoustic correlates of pitch in whisper have been sought in vowel content, but, recently, studies of normal speech demonstrated correlates of intonation in consonants as well. This study examined how consonants may contribute to the coding of intonation in whispered relative to normal speech. The acoustic characteristics of whispered, voiceless fricatives /s/ and /f/, produced at different pitch targets (low, mid, high), were investigated and compared to corresponding normal speech productions to assess if whisper contained secondary or compensatory pitch correlates. Furthermore, listener sensitivity to fricative cues to pitch in whisper was established, also relative to normal speech. Consistent with recent studies, acoustic correlates of whispered and normal speech fricatives systematically varied with pitch target. Comparable findings across speech modes showed that acoustic correlates were secondary. Discrimination of vowel-fricative-vowel stimuli was less accurate and slower in whispered than normal speech, which is attributed to differences in acoustic cues available. Perception of fricatives presented without their vowel contexts, however, revealed comparable processing speeds and response accuracies between speech modes, supporting the finding that within fricatives, acoustic correlates of pitch are similar across speech modes.

Managed estimation of psychophysical thresholds

Objective: The estimation of perceptive thresholds is a basic element of psychoacoustics. One of the drawbacks of commonly used adaptive algorithms is the lack of reliability when the behavioral response is not robust. To address this issue an adaptive algorithm, TEMA (Threshold Estimation by Managed Algorithm), has been developed. Design: TEMA seeks the 50% point on the psychometric curve based on an up-down staircase procedure. Internal controls and stochastic processes aim at enhancing the reliability. The development of TEMA is described, together with its validations with reference to common adaptive procedures. Both Monte Carlo simulations and real subject testing were performed to assess the psychoacoustic threshold in intonation perception tests and the number of stimulus presentations needed. Study sample: A total of 29 adult listeners participated in the within-subjects comparison; 19 listeners had normal-hearing, the other 10 were hearing impaired (5 aided, 5 unaided). Results: The results show that TEMA outperformed commonly used algorithms in non-robust responders, with a minimal cost in terms of test duration. Conclusions: TEMA’s adaptive algorithm was shown to be significantly more resistant to gambling or cheating behavior and threshold drift than traditional, reversal-based algorithms. TEMA increases the accuracy of threshold estimation and the test reliability in non-robust responders. This makes TEMA applicable for automated threshold measurements in clinical settings. EVALUACION CONTROLADA DE LOS UMBRALES PSICOFISICOS