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The effect of several factors upon voice identification was examined. These factors were: the size of the class of possible voices, the duration of the speech signal, the frequency range of the speech signal, voicing vs nonvoicing speech characteristics, and the simultaneous presentation of several voices. One of the most effective factors for speaker identification was the duration of the speech signal. Duration, as such, appears to be important, however, only insofar as it admits a smaller or larger statistical sampling of the speaker's speech repertoire.

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Excised speech samples, excerpted from the conversational speech of college female speakers, were presented to listeners for identification. The average intelligibility of such samples increases with the duration of the excised utterance, and is relatively independent of the average rate of speaking. The results are interpreted such that talkers aim for a constant precision of communication, trading off the precision of enunciation associated with the rate of speaking against the additional context associated with the number of words.

Reception of consonants was studied with normal-heating subjects in a sound-treated classroom, at reverberation times T•_0.3 and 0.6 sec, to compare binaural and monaural reception, with and without heating aids, in the presence of an impulsive noise (16 imp/sec) and a quasisteady noise (a babble of eight voices). The consonants were spoken in words inbedded in a rapidly spoken cartier phrase. The speech and noise sources subtended an angle of 60 ø on a circle 11 ft in radius centered on the listener, to give a large advantage for binaural reception. Binaural gain was taken as the difference in speech-to-noise ratios for 60% correct reception comparing binaural and monaural results. The binaural gain at short reverberation, with unaided listening, was 5 dB in the presence of the babble and 4 dB in the presence of the impulsive noise. The introduction of heating aids and the increase in reverberation each caused the binaural gain to decrease to 3 dB. The small increase in reverberation caused a substantial decrease in reception under the noise conditions tested. Analysis of the consonant responses to reflect reception of the phonetic features of voicing, manner, and place, for both initial and final consonants, indicated that the acoustic conditions of reverberation and binaural listening affected feature reception in predictable ways. Subject Classification' 70.30; 65.64, 65.62; 50.70; 55.20. The purpose of this experiment was to study the influence of noise and reverberation on monaural and binaural reception of consonants. Our interest in these effects stems from the need to specify optimum acoustic conditions in schoolrooms for hearing-impaired pupils. We wanted to have data that would indicate the degree and type of improvement obtainable through binaural hearing aids versus using a single aid and depending on the conditions of noise and reverberation. A review of the literature convinced us that our first study should employ normal-hearing listeners because certain important conditions had not been present in previous studies. There were no studies using a combination of open-ear listening, realistic types of noise, and conditions of reverberation that were typical of rooms of classroom size with varied amounts of sound treatment. We thought it would be prudent to obtain normal baseline data under these conditions before introducing the complications of hearing impairment. The tests were carried out in a special room which was constructed so that the reverberation could be changed. The following factors were investigated: (1) two different conditions of reverberation, (2) steady and impulsive masking noises, (3) monaural versus binaural modes of listening, and (4) normal unaided listening compared with aided listening through hearing aids. We analyze our results first in terms of overall percent correct reception, and then in more specific ways to examine reception of individual consonants, initial consonants, final consonants, and the phonetic features of consonants. The more specific analyses are designed ...