Develop. Med. Child Neurol. 1977, 19, 309-315
Sound Spectrographic Cry Analysis of Infants with Bacterial Meningitis Katarina Michelsson Pertti Sirvio
Ole Wasz-Hockert
H. influenzae and in two cases by D . pneumoniae; in the other two cases the
Introduction This sound spectrographic study of crying in newborn infants with bacterial meningitis is a part of a large, continuing research project in which the cry characteristics are evaluated by sound spectrographic methods in newborn infants, both healthy and with various diseases and congenital abnormalities. In all phonation, and thus also crying, the sound produced is not only a neuromuscular activity of the larynx and of the oral cavities but also reflects brain function, as the neural impulses to the voiceproducing organs originate from the brain. By analysing cries, we try to evaluate not only in which diseases the cry pattern is different from normal crying, but also which characteristics can be caused by disturbances in the larynx and in the oral cavities and which are caused by disturbances in the function of the brain. In evaluating how the cry changes in certain diseases, cry analysis can be used as one more method of diagnosis and later prognosis.
disease was meningococcal and streptococcal. The children were treated between 1972 and 1976 at the Children’s Hospital, University of Helsinki. A t the time of diagnosis eight of the infants were less than six weeks of age and six were between two and six months old. The cries were recorded from all infants within one to three days of making the diagnosis, and cries from 10 of the infants were recorded again one to three weeks later. Altogether 110 cry signals were analysed, between five and 18 cries from each infant. All but two of the infants were born at term with birthweights over 3000g. The other were born after 36 weeks gestation, with birthweights of 23508 and 25708. All the infants had good Apgar scores at birth and none had hypoglycaemia. One infant had a bilirubin value of 258mmol/l at the time of the first cry recordings. At a check-up examination between four and 18 months after the meningitis, seven of the 14 infants were healthy, three had spastic hemiplegia (two of whom also had impaired hearing), two had developed hydrocephalus and two subdural haemat-
Material The cries were tape-recorded from 14 infants with bacterial meningitis, caused in six cases by E. coli, in four cases by
Correspondence to Katarina Michelsson, M.D., Helsinki University Central Hospital, Stenbackstreet 11, Helsinki 29, Finland.
309
DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY.
1977, 19
oma. 66 cries were analysed from the infants who were healthy at the follow-up examination and 49 cries were recorded from those with later sequelae. The control series comprised 75 healthy, full-term newborn infants.
Schonander, Sweden) was used for measuring the durational features. More detailed information on the analysing technique is given in monographs by Wasz-Hockert et al. (1968) and by Michelsson (1971).
Methods The pain-induced cries from all the infants were recorded on a Sony TC 55 cassette tape-recorder. The cry recordings were analysed with a Sona-Graph 6061-B (Kay Elemetrics, USA) sound spectrograph. This apparatus, widely used in phonetics, gives a visual image of the cry signal (a sonagram) on which the time is on the horizontal axis and the frequency on the vertical axis. Different cry characteristics can be measured from the spectrograms. Some of the most important features of the spectrograms are presented schematically in Figure 1. From the features related to the tonal properties, we analysed the maximum and minimum pitch of the fundamental frequency, the occurrence and maximum pitch of shift, the melodic fdrm, the part of purely voiced signals, and the occurrence of bi-phonation, gliding, double harmonic break, vibrato and glottal roll. From the time features we measured the duration of phonation and continuity of signals. A Mingograph T 34 jet-ink writer (Elema
Results The results of the analysis of 110 cries of 14 infants with bacterial meningitis are presented in Table I. When compared with the crying of 75 healthy newborn, the following cry characteristics in the meningitic babies were significantly different from normal crying. The minimum and the maximum pitch of the fundamental frequency was increased, and an increase in rising, falling-rising and flat types of melodic cry was noted. Bi-phonation and gliding occurred more often, double harmonic break and glottal roll less often. The signals were significantly shorter and consisted more often of voiceless parts. Comparison of the cries of the meningitic babies who were healthy at later examination (66 cries) with those of the infants with later sequelae (49 cries) revealed that the pitch of the fundamental frequency was not different (Table 11). However, when the infant had neurological sequelae the signals were shorter, more voiced and continuous, and showed a striking increase in rising, falling-rising, flat and no types of melody (68 per cent versus 37 per cent in the meningitic babies without sequelae and 15 per cent in the controls).
1.o
2.0 sec.
Fig. 1. Schematic drawing of sonagram, displaying the following characteristics: ( I ) maximum pitch of shift; (2) maximum pitch of fundamental frequency; (3) minimum pitch of fundamental frequency; (4) bi-phonation; ( 5 ) double harmonic break; (6) vibrato; (7) gliding and (8) furcation.
310
Discussion Wasz-Hockert and co-workers (1968) and Michelsson (1971) found that the cry of healthy newborn infants has a fundamental frequency between 400 and 600Hz, and in about one-third of the cries there is a more high-pitched shift section, mainly at the beginning of the signals. The
KATARINA MICHELSSON
PERTTI SIRVIO
OLE WASZ-HOCKERT
TABLE I Cry analysis from infants with meningitis compared with healthy neonates
No. of infants No. of cries analysed Duration of phonation (secs., Md) Maximum pitch (Hz, Md) Minimum pitch (Hz, Md) Occurrence of shift (%) Maximum pitch of shift (Hz, Md) Continuous signals (%) Voiced phonations (%) Melodic type (%) : falling rising-falling rising falling-rising flat none Instability of fundamental frequency (%) Bi-phonation (%) Gliding (%) Double harmonic break (%) Vibrato (%) Glottal roll (%) p
Sound Spectrographic Cry Analysis of Infants with Bacterial Meningitis Katarina Michelsson Pertti Sirvio
Ole Wasz-Hockert
H. influenzae and in two cases by D . pneumoniae; in the other two cases the
Introduction This sound spectrographic study of crying in newborn infants with bacterial meningitis is a part of a large, continuing research project in which the cry characteristics are evaluated by sound spectrographic methods in newborn infants, both healthy and with various diseases and congenital abnormalities. In all phonation, and thus also crying, the sound produced is not only a neuromuscular activity of the larynx and of the oral cavities but also reflects brain function, as the neural impulses to the voiceproducing organs originate from the brain. By analysing cries, we try to evaluate not only in which diseases the cry pattern is different from normal crying, but also which characteristics can be caused by disturbances in the larynx and in the oral cavities and which are caused by disturbances in the function of the brain. In evaluating how the cry changes in certain diseases, cry analysis can be used as one more method of diagnosis and later prognosis.
disease was meningococcal and streptococcal. The children were treated between 1972 and 1976 at the Children’s Hospital, University of Helsinki. A t the time of diagnosis eight of the infants were less than six weeks of age and six were between two and six months old. The cries were recorded from all infants within one to three days of making the diagnosis, and cries from 10 of the infants were recorded again one to three weeks later. Altogether 110 cry signals were analysed, between five and 18 cries from each infant. All but two of the infants were born at term with birthweights over 3000g. The other were born after 36 weeks gestation, with birthweights of 23508 and 25708. All the infants had good Apgar scores at birth and none had hypoglycaemia. One infant had a bilirubin value of 258mmol/l at the time of the first cry recordings. At a check-up examination between four and 18 months after the meningitis, seven of the 14 infants were healthy, three had spastic hemiplegia (two of whom also had impaired hearing), two had developed hydrocephalus and two subdural haemat-
Material The cries were tape-recorded from 14 infants with bacterial meningitis, caused in six cases by E. coli, in four cases by
Correspondence to Katarina Michelsson, M.D., Helsinki University Central Hospital, Stenbackstreet 11, Helsinki 29, Finland.
309
DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY.
1977, 19
oma. 66 cries were analysed from the infants who were healthy at the follow-up examination and 49 cries were recorded from those with later sequelae. The control series comprised 75 healthy, full-term newborn infants.
Schonander, Sweden) was used for measuring the durational features. More detailed information on the analysing technique is given in monographs by Wasz-Hockert et al. (1968) and by Michelsson (1971).
Methods The pain-induced cries from all the infants were recorded on a Sony TC 55 cassette tape-recorder. The cry recordings were analysed with a Sona-Graph 6061-B (Kay Elemetrics, USA) sound spectrograph. This apparatus, widely used in phonetics, gives a visual image of the cry signal (a sonagram) on which the time is on the horizontal axis and the frequency on the vertical axis. Different cry characteristics can be measured from the spectrograms. Some of the most important features of the spectrograms are presented schematically in Figure 1. From the features related to the tonal properties, we analysed the maximum and minimum pitch of the fundamental frequency, the occurrence and maximum pitch of shift, the melodic fdrm, the part of purely voiced signals, and the occurrence of bi-phonation, gliding, double harmonic break, vibrato and glottal roll. From the time features we measured the duration of phonation and continuity of signals. A Mingograph T 34 jet-ink writer (Elema
Results The results of the analysis of 110 cries of 14 infants with bacterial meningitis are presented in Table I. When compared with the crying of 75 healthy newborn, the following cry characteristics in the meningitic babies were significantly different from normal crying. The minimum and the maximum pitch of the fundamental frequency was increased, and an increase in rising, falling-rising and flat types of melodic cry was noted. Bi-phonation and gliding occurred more often, double harmonic break and glottal roll less often. The signals were significantly shorter and consisted more often of voiceless parts. Comparison of the cries of the meningitic babies who were healthy at later examination (66 cries) with those of the infants with later sequelae (49 cries) revealed that the pitch of the fundamental frequency was not different (Table 11). However, when the infant had neurological sequelae the signals were shorter, more voiced and continuous, and showed a striking increase in rising, falling-rising, flat and no types of melody (68 per cent versus 37 per cent in the meningitic babies without sequelae and 15 per cent in the controls).
1.o
2.0 sec.
Fig. 1. Schematic drawing of sonagram, displaying the following characteristics: ( I ) maximum pitch of shift; (2) maximum pitch of fundamental frequency; (3) minimum pitch of fundamental frequency; (4) bi-phonation; ( 5 ) double harmonic break; (6) vibrato; (7) gliding and (8) furcation.
310
Discussion Wasz-Hockert and co-workers (1968) and Michelsson (1971) found that the cry of healthy newborn infants has a fundamental frequency between 400 and 600Hz, and in about one-third of the cries there is a more high-pitched shift section, mainly at the beginning of the signals. The
KATARINA MICHELSSON
PERTTI SIRVIO
OLE WASZ-HOCKERT
TABLE I Cry analysis from infants with meningitis compared with healthy neonates
No. of infants No. of cries analysed Duration of phonation (secs., Md) Maximum pitch (Hz, Md) Minimum pitch (Hz, Md) Occurrence of shift (%) Maximum pitch of shift (Hz, Md) Continuous signals (%) Voiced phonations (%) Melodic type (%) : falling rising-falling rising falling-rising flat none Instability of fundamental frequency (%) Bi-phonation (%) Gliding (%) Double harmonic break (%) Vibrato (%) Glottal roll (%) p
