Pitch in esophageal speech.
Most reports on pitch in esophageal speech emphasize that it is low-pitched with a measured fundamental frequency rarely higher than 100 cps. Our investigations show, however, that much esophageal 'phonation' lacks periodicity and, therefore, a fundamental frequency (i.e. pitch in the accepted sense). An auditory impression of pitch modulation can, nevertheless, be created by physical properties other than a varying harmonic structure. Our sample includes a rare case of truly high-pitched esophageal phonation with a fundamental frequency in the upper limit of the voice an octave higher than the highest reported in the literature. High-pitched phonation apparently requires a vibratory source in a 'mode' different from that of low-pitched phonation and should therefore be distinguished from it in discussing pitch in esophageal voice.
Selected acoustic characteristics of emerging esophageal speech: case study.
The development of esophageal speech was examined in a laryngectomee subject to observe the emergence of selected acoustic characteristics, and their relation to listener intelligibility ratings. Over a two-and-a-half  month period, the data from  five recording sessions was used for spectrographic and perceptual (listener) analysis. There was evidence to suggest a fairly reliable correlation between emerging acoustic characteristics and increasing perceptual ratings. Acoustic factors coincident with increased intelligibility ratings appeared related to two dimensions: firstly, the increasing pseudoglottic control over esophageal air release; secondly the presence of  a mechanism of  pharyngeal compression. Increased pseudoglottic control manifested  in a reduction of  tracheo-esophageal turbulence, and a more efficient  burping mode of  vibration with clearer formant structure. Spectrographic evidence of  a fundamental  frequency  did not emerge. These dimensions appeared to have potential diagnostic and therapeutic value, rendering an analysis of  the patient's developing vocal performance  more explicit for  both clinician and patient.
A model of field induced electron emission from ionically-conducting glasses
Electrons are field emitted from borosilicate glasses into a vacuum following a Schottky-like equation i=A exp(-( phi -aF12/)/kT) with phi =1 eV. Thermionic fields emission may occur from a 1 eV trap, but two other mechanisms which take account of ion movement are considered. As a cation migrates into the glass towards the cathode, the electron, which may be present as O-, is destabilised by an energy given by a screened Coulomb potential. The measured emission characteristics may thus be of a destabilised electron. If this process is sufficient to emit an electron with little or no activation energy, the observed emission will depend on the movement of the cation, i.e. the ionic conductivity of the glass. Electrons in traps of energy around 1 eV may be responsible for field stimulated exoelectron emission which has recently been reported.