A microscopic investigation of the effect of random envelope fluctuations on phoneme-in-noise perception.

In this study, we investigated the effect of specific noise realizations on the discrimination of two consonants, /b/ and /d/. For this purpose, we collected data from twelve participants, who listened to /aba/ or /ada/ embedded in one of three background noises. All noises had the same long-term spectrum but differed in the amount of random envelope fluctuations. The data were analyzed on a trial-by-trial basis using the reverse-correlation method. The results revealed that it is possible to predict the categorical responses with better-than-chance accuracy purely based on the spectro-temporal distribution of the random envelope fluctuations of the corresponding noises, without taking into account the actual targets or the signal-to-noise ratios used in the trials. The effect of the noise fluctuations explained on average 8.1% of the participants' responses in white noise, a proportion that increased up to 13.3% for noises with a larger amount of fluctuations. The estimated time-frequency weights revealed that the measured effect originated from confusions between noise fluctuations and relevant acoustic cues from the target sounds. Similar conclusions were obtained from simulations using an artificial listener.

Prosodic cues to word boundaries in a segmentation task assessed using reverse correlation.

When listening to speech sounds, listeners are able to exploit acoustic features that mark the boundaries between successive words, the so-called segmentation cues. These cues are typically investigated by directly manipulating features that are hypothetically related to segmentation. The current study uses a different approach based on reverse correlation, where the stimulus manipulations are based on minimal assumptions. The method was evaluated using pairs of phonemically identical sentences in French, whose prosody was changed by introducing random f0 trajectories and segment durations. Our results support a prominent perceptual role of the f0 rise and vowel duration at the beginning of content words.

Modest improvement in CVD risk markers in older adults following quinoa (Chenopodium quinoa Willd.) consumption: a randomized-controlled crossover study with a novel food product.

PURPOSE: To investigate the effect of consuming quinoa biscuits on markers of CVD risk over 4 weeks in free-living older adults. METHODS: A randomized-controlled, double-blind crossover trial was conducted in which consenting healthy adults aged 50-75 years (n = 40) consumed 15 g quinoa biscuits (60 g quinoa flour/100 g) or control iso-energetic biscuits (made using wheat flour) daily for 28 consecutive days (4 weeks), in addition to their normal diet. Following a 6-week washout, participants consumed the alternate biscuit for a final 4 weeks. Anthropometry and fasted blood samples were obtained before and after each intervention period. RESULTS: At the beginning of the trial, mean ± SD total cholesterol concentrations were 6.02 ± 1.22 mmol/L (3.7-9.2 mmol/L); 33 participants (82.5%) had high cholesterol (> 5 mmol/L). No participants were lost to follow-up and there were no changes in habitual dietary intakes or levels of physical activity between each 4-week intervention period. Significantly greater decreases in total and LDL cholesterol concentrations (- 0.30 ± 0.58 and - 0.25 ± 0.38 mmol/L, respectively), TC: HDL ratio (- 0.11 ± 0.30), weight (- 0.61 ± 0.89 kg) and BMI (- 0.22 ± 0.34 kg/m2) were apparent following consumption of the quinoa versus control biscuits (all P < 0.05). Changes in triglycerides, HDL cholesterol, or PUFA or CRP concentrations were not significant between treatment groups. CONCLUSION: Consumption of novel quinoa biscuits produced small, but favorable changes in body weight, BMI, and circulating cholesterol concentrations, all of which may contribute to lowered CVD risk in older adults.

Speech perception with F0mod, a cochlear implant pitch coding strategy.

OBJECTIVE: The fundamental frequency modulation (F0mod) sound processing strategy was developed to improve pitch perception with cochlear implants. In previous work it has been shown to improve performance in a number of pitch-related tasks such as pitch ranking, familiar melody identification, and Mandarin Chinese tone identification. The objective of the current study was to compare speech perception with F0mod and the standard clinical advanced combination encoder (ACE) strategy. STUDY SAMPLE: Seven cochlear-implant listeners were recruited from the clinical population of the University Hospital Leuven. DESIGN: F0mod was implemented on a real-time system. Speech recognition in quiet and noise was measured for seven cochlear-implant listeners, comparing F0mod with ACE, using three different Dutch-language speech materials. Additionally the F0 estimator used was evaluated physically, and pitch ranking performance was compared between F0mod and ACE. RESULTS: Immediately after switch-on of the F0mod strategy, speech recognition in quiet and noise were similar for ACE and F0mod, for four out of seven listeners. The remaining three listeners were subjected to a short training protocol with F0mod, after which their performance was reassessed, and a significant improvement was found. CONCLUSIONS: As F0mod improves pitch perception, for the seven subjects tested it did not interfere with speech recognition in quiet and noise, and has a low computational complexity, it seems promising for implementation in a clinical sound processor.