<p>Hypernasality assessment in speech produced by children with cleft palate often relies on perceptual ratings provided by experienced speech-language pathologists. However, these ratings are inherently subjective and may vary between raters. In contrast, instrumental measures offer a more objective approach, though they come with certain limitations To address these issues, researchers have been developing objective measures for assessing hypernasality based on spectral analysis of speech using digital signal processing techniques. This approach captures nasality cues in nasalized vowels using various features, facilitating the detection and assessment of hypernasality severity. These features can be temporal, derived from formant analysis, or based on cepstral coefficients. This paper aims to review the current literature on spectral analysis-based methods for hypernasality detection. It will first examine the different nasal cues identified for nasalized vowels and then discuss the various techniques used for distinguishing between normal and hypernasal speech, as well as for assessing the severity of hypernasality.</p>