Effects of maturation on tympanometric wideband acoustic transfer functions in human infants

• Published in: The Journal of the Acoustical Society of America 2008-10, Vol.124 (4), p.2106-2122
• Main Authors: Sanford, Chris A., Feeney, M. Patrick
• Format: Article
• Language: English
• Subjects: Acoustic Impedance Tests; Acoustic Stimulation; Acoustical measurements and instrumentation; Acoustics; Adult; Age Factors; Aging - physiology; Biological and medical sciences; Cross-Sectional Studies; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Ear Canal - anatomy & histology; Ear Canal - growth & development; Ear, Middle - anatomy & histology; Ear, Middle - growth & development; Exact sciences and technology; Female; Fundamental and applied biological sciences. Psychology; Fundamental areas of phenomenology (including applications); Humans; Infant; Infant, Newborn; Male; Otoacoustic Emissions, Spontaneous; Physics; Pressure; Signal Processing, Computer-Assisted; Vertebrates: nervous system and sense organs; Young Adult
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.2967864

Wideband acoustic transfer function (ATF) measurements of energy reflectance (ER) and admittance magnitude ( ∣ Y ∣ ) were obtained at varying static ear-canal pressures in 4-, 12-, and 27 - week -old infants and young adults. Developmental changes in wideband ATF measurements varied as a function of frequency. For frequencies from 0.25 to 0.75 kHz there was as much as a 30% change in mean ER and ∣ Y ∣ with changes in static ear-canal pressure between 4 and 24 weeks of age. From 0.75 to 2 kHz , the effects of pressure produced a small number of significant differences in ER and ∣ Y ∣ with age, suggestive of a developmentally stable frequency range. Between 2 and 6 kHz , there were differential effects of pressure for the youngest infants; negative pressures caused increased ER and ∣ Y ∣ and positive pressures caused decreased ER and ∣ Y ∣ ; the magnitude of this effect decreased with age. Findings from this study demonstrate developmental differences in wideband tympanometric ATF measurements in 4-, 12- and 24 - week -old infants and provide additional insight on the effects of static ear-canal pressure in the young infant's ear. The maturational effects shown in the experimental data are discussed in light of known age-related anatomical changes in the developing outer and middle ear.