The paper explores the acoustic signatures in the primary microwave background (CMB) bispectrum, focusing on detecting non-Gaussianity in the CMB sky. It discusses how non-Gaussianity, if present in primordial fluctuations, would be evident in the CMB. The study uses the full transfer function to calculate the angular bispectrum of the primary CMB anisotropy, revealing a series of acoustic peaks that change sign and have a period twice that of the angular power spectrum. The paper estimates the signal-to-noise ratio for detecting the primary bispectrum using COBE, MAP, and Planck experiments, finding that the coupling parameter must be larger than 600, 20, and 5, respectively, for detection. The study also compares the sensitivity of the primary bispectrum to the primary skewness, concluding that the bispectrum is a more powerful tool for detecting non-Gaussianity. The paper further discusses the separation of the primary bispectrum from various secondary bispectra, noting that MAP and Planck can distinguish them based on shape differences. The primary CMB bispectrum is a test of the inflationary scenario and a probe of non-linear physics in the early universe. The paper also addresses the detection of non-Gaussianity in the COBE map, and the potential for future CMB experiments to detect the primary bispectrum. The study concludes that the primary bispectrum is a key tool for understanding the early universe and testing inflationary models.The paper explores the acoustic signatures in the primary microwave background (CMB) bispectrum, focusing on detecting non-Gaussianity in the CMB sky. It discusses how non-Gaussianity, if present in primordial fluctuations, would be evident in the CMB. The study uses the full transfer function to calculate the angular bispectrum of the primary CMB anisotropy, revealing a series of acoustic peaks that change sign and have a period twice that of the angular power spectrum. The paper estimates the signal-to-noise ratio for detecting the primary bispectrum using COBE, MAP, and Planck experiments, finding that the coupling parameter must be larger than 600, 20, and 5, respectively, for detection. The study also compares the sensitivity of the primary bispectrum to the primary skewness, concluding that the bispectrum is a more powerful tool for detecting non-Gaussianity. The paper further discusses the separation of the primary bispectrum from various secondary bispectra, noting that MAP and Planck can distinguish them based on shape differences. The primary CMB bispectrum is a test of the inflationary scenario and a probe of non-linear physics in the early universe. The paper also addresses the detection of non-Gaussianity in the COBE map, and the potential for future CMB experiments to detect the primary bispectrum. The study concludes that the primary bispectrum is a key tool for understanding the early universe and testing inflationary models.