Abstract
The aim of the present study was to discover acoustical features in the crying of children at the stage of language acquisition. As samples of the present study, sounds of crying of 2 and 3 year old children during dental visiting were recorded. We performed Fourier-transformation and made soundspectrograms from the wave files of the sounds of crying.
Firstly,6 volunteer evaluators, who were students of dentistry, evaluated the loudness and bitterness of the sounds of crying based on their subjective auditory-impression without fundamental knowledge of acoustics. From the results, we tried to select typical waveforms of sounds of crying, and then we discriminated two type of waveforms from the difference of those noise densities on the sound spectrograms. They were named N type and C type waveforms of crying, former one had high density of noise between formants and later one had low density and the layer structure, that was clearer than those of the N type of crying.
Secondly, we arranged 8 files (F1 to F8) of cry sounds which were comprised of two waveforms of cries. Four of the files ( F1 to F4) were combinations of loud or low crying of the N or C type of crying, which were selected by the evaluators. The others were combination of the N or C type of crying, of which the frequency or sound pressure were modified digitally. Thirteen pediatric dentists listened to the sounds in the 8 files and evaluated their auditory impression to clarify the relationship between the waveforms of crying and the auditory impression.
To compare the sounds of crying in F1 (Loud N: Loud C), F2 (Low N: Low C), F3 (Loud N: Low N) and F4 (Loud C: Low C),100%,100%,78% and 85% of the listeners felt that the former one of the two sounds of crying was more angry undesirable than the later one, respectively. They felt, however, the loudness of those sounds of crying were same in F1 and F3. Contrary to this, in F 2 and F4,94% of them felt the former sounds of crying were louder.
The results indicated that the N type of crying caused a stronger of lament to the listener than the C type of crying. Interestingly, the results from the other files (F5 to F8) of modified sounds of crying suggested that the impression of the N type of crying was almost independent from the frequency or sound pressure of these sounds of crying.
