A Pilot Comparative Study of Vocal and Instrumental Acoustic Stimulation on Early Embryonic Brain Morphology in Gallus gallus
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Introduction. Early embryonic brain development can respond to environmental factors, including sound. Sound waves create mechanical vibrations that affect cellular activity through mechano transduction. This study examined the effects of rhythmic vocal and harmonic instrumental acoustic stimulation on early brain development. Methods. We randomly assigned 20 fertilized chicken eggs to two groups: rhythmic vocal stimulation (Qur'anic recitation, n = 10) and harmonic instrumental stimulation (classical music, n = 10). We exposed the eggs to sound for 5 days, from embryonic day 1 to day 5. On day 5, we collected and examined the embryos. We assessed brain development based on embryo viability and the morphology of the primary brain vesicles. We used Fisher's Exact Test to compare developmental outcomes between the two groups. Results. Eight embryos (80%) developed in the rhythmic vocal group, while seven embryos (70%) developed in the harmonic instrumental group. The difference was not statistically significant (p > 0.05). However, Qualitative microscopic observation noted that primary brain vesicles appeared more clearly delineated in the rhythmic vocal group; however, this observation was descriptive and was not confirmed by quantitative morphometric measurement. Conclusion. Although the difference was not statistically significant, rhythmic vocal stimulation raise the hypothesis that rhythmic vocal stimulation may be associated with more distinct brain vesicle morphology. Because this was a pilot study with a small sample size, further studies using larger sample sizes and histological, biochemical, and molecular analyses are needed to better understand the biological effects of acoustic stimulation during embryonic development.
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