Writedown versus talkback scoring and scoring bias in speech discrimination testing

Writedown and talkback responses to 500 Hz low-pass filtered CID W-22 words were obtained from eight listeners, and their talkback responses were scored by eight experienced and eight inexperienced examiners. Four of the experienced and four of the inexperienced examiners monitored at 70 dB SPL; four experienced and four inexperienced examiners monitored at 60 dB SPL. Comparison of talkback discrimination scores (DSs) with corresponding writedown DSs revealed: (1) Inexperienced examiners awarded significantly higher mean talkback DSs than the mean writedown DS; i.e., they showed a mean correct bias. (2) Experienced examiners produced talkback DSs that were not significantly different from the mean writedown DS. (3) Decreasing the monitoring level from 70 to 60 dB SPL increased inexperienced examiners' mean correct bias but the experienced examiners' mean talkback DSs did not change significantly with monitoring level. (4) Inexperienced examiners made more scoring errors than experienced examiners at both monitoring levels. (5) Most examiners iri both groups made both correct bias and incorrect bias scoring errors to produce a net effect on the talkback DS. (6) Distributions of DS differences show individual differences between talkback and writedown DSs as large as +16% and −20% and frequent differences of ±6%, even when the mean DS difference between scoring methods was negligible.

The effects of variable-interval and fixed-interval signal presentation schedules on the auditory evoked response

Averaged auditory evoked responses to 1000-Hz 20-msec tone bursts were obtained from normal-hearing adults under two different intersignal interval schedules: (1) a fixed-interval schedule with 2-sec intersignal intervals, and (2) a variable-interval schedule of intersignal intervals ranging randomly from 1.0 sec to 4.5 sec with a mean of 2 sec. Peak-to-peak amplitudes (N 1 — P 2 ) as well as latencies of components P 1 , N 1 , P 2 , and N 2 were compared under the two different conditions of intersignal interval. No consistent or significant differences between variable- and fixed-interval schedules were found in the averaged responses to signals of either 20 dB SL or 50 dB SL. Neither were there significant schedule differences when 35 or 70 epochs were averaged per response. There were, however, significant effects due to signal amplitude and to the number of epochs averaged per response. Response amplitude increased and response latency decreased with sensation level of the tone burst.

The venom of the honeybee (Apis mellifera): free amino acids and peptides

The venom of the honeybee (Apis mellifera), obtained by electrical excitation, was fractionated by solvent extraction and gel filtration. The free amino acid and peptide content was determined by automated analysis. Less than 1% of the venom consisted of 19 free amino acids, while the minimum quantity of the 14 peptides was 15%. Two histapeptides were isolated and characterized. The sequence of histapeptide A was alanyl-glycyl-prolyl-alanyl-glutaminyl-histamine.