Physiology. — “On the Inder Loquelae’. By F. Roers and L. Morr. 
(Communicated by Prof. H. ZWAARDEMAKER). 
(Communicated in the meeting of December 28, 1918). 
The idea index vocalis has been introduced by GRADENIGO *) and 
denotes the quantitative relation between whispers of moderate energy 
and ordinary speech. Practically this relation is best determined with 
the aid of the extreme distances at which they are audible. According 
to GRADENIGO the average index for vowels is */, or’/,*). According 
to Worr®), ZWAARDEMAKER*), and Reuter’) the average index ranges 
from */, to */,. For twenty monosyllabic, aequiintensive, isozonal 
test-words ZWAARDEMAKER—QuIx *) and Reuter’) found the index */,,. 
The determination of the relative energy of whispers and ordinary 
speech being rather difficult (as it is difficult to distinguish exactly 
between what is meant by the one and what by the other), 
ZWAARDEMAKER has had recourse to RALRIGH's mirror for sound- 
measurement*). [t then appeared that the normal average index 
_ reserve-air whisper 
vocalis ———— = '/,,, the normal average index vocalis 
ordinary speech 
stage- whisper 
: = '/,. These indices enable us to reduce the whisper- 
ordinary speech 
values obtained for vowels and words to ordinary speech-values. 
In experimenting on the intensity of audition separate words are 
used which consist of isozonal and aequi-intensive sounds, which, for 
1) GRADENIGO. Communication au congrés internat. d’otologie. Budapest 1909 
GRADENIGO et STEFANINI. Sur l'acoumétrie. Propositions et études. Archives internat. 
de laryngolie, d’otologie et de rhinologie, 1911. 
2) ZWAARDEMAKER. Over den index vocalis bij keuringen en bij de studie der 
ziektebeelden. (Handelingen van het XIVe. Ned. Nat.- en Gen. Congres te Delft 1913), 
p. 370. 
8) Worr. Sprache und Ohr. 1870. Frankfurt. 
4) ZWAARDEMAKER bid. 
5) Reuter. Zeitschr. f. Ohrenheilkunde. Bd. 47, blz. 91; Onderzoekingen Physiol. 
Lab. Utrecht (5) Vol. 5. p. 239. 
6) ZWAARDEMAKER. Over geluidmeting. Zittingsverslag dezer Academie van 23 
April 1915. Vol. XXIII. p. 1405. 
7) Reuter. Onderzoekingen Physiol. Lab. Utrecht (5) Vol. 5. p. 249. 
8) ZWAARDEMAKER and Qurx. De studie van het spraakgehoor. Onderzoekingen 
Physiol. Lab. Utrecht (5) Vol. 5. p. 1. 
