Acoustical analysis of tracheoesophageal voice

Acoustical voice analysis of laryngectomees is a complicated matter because of the often weak periodicity of the voice and the high noise component. This study consists of a feasibility study and validation of an acoustical tracheoesophageal (TE) voice analysis on a sustained vowel based upon recordings of 66 laryngectomees from four clinics in three European countries. Based on reliability analysis of the acoustical data, TE voices can be objectively divided in three categories: (I) good voices with low-frequency harmonics and noise taking over at the higher frequencies; (II) moderate voices consisting of repetitive bursts of sound energy with low repetition rate and a weak periodicity due to high levels of noise, even at the low frequencies; (III) poor voices with no detectable or very weak fundamental frequency or envelope periodicity. The voice samples from category I and II correlate well with perceptually analyzed voice quality parameters, which supports the robustness and validation of this acoustical analysis method to analyze TE voices

Tropical forests are approaching critical temperature thresholds

The critical temperature beyond which photosynthetic machinery in tropical trees begins to fail averages approximately 46.7 °C (Tcrit)1. However, it remains unclear whether leaf temperatures experienced by tropical vegetation approach this threshold or soon will under climate change. Here we found that pantropical canopy temperatures independently triangulated from individual leaf thermocouples, pyrgeometers and remote sensing (ECOSTRESS) have midday peak temperatures of approximately 34 °C during dry periods, with a long high-temperature tail that can exceed 40 °C. Leaf thermocouple data from multiple sites across the tropics suggest that even within pixels of moderate temperatures, upper canopy leaves exceed Tcrit 0.01% of the time. Furthermore, upper canopy leaf warming experiments (+2, 3 and 4 °C in Brazil, Puerto Rico and Australia, respectively) increased leaf temperatures non-linearly, with peak leaf temperatures exceeding Tcrit 1.3% of the time (11% for more than 43.5 °C, and 0.3% for more than 49.9 °C). Using an empirical model incorporating these dynamics (validated with warming experiment data), we found that tropical forests can withstand up to a 3.9 ± 0.5 °C increase in air temperatures before a potential tipping point in metabolic function, but remaining uncertainty in the plasticity and range of Tcrit in tropical trees and the effect of leaf death on tree death could drastically change this prediction. The 4.0 °C estimate is within the ‘worst-case scenario’ (representative concentration pathway (RCP) 8.5) of climate change predictions2 for tropical forests and therefore it is still within our power to decide (for example, by not taking the RCP 6.0 or 8.5 route) the fate of these critical realms of carbon, water and biodiversity