Salience arises from acoustic features such as duration, intensity, and spectral change ([2]). Diphthongs, due to formant movement, involve dynamic acoustic variation that may enhance perceptual prominence.

Stress and musical emphasis often coincide ([6]; [9]), creating perceptual peaks. Dynamic acoustic features are therefore likely to be amplified when aligned with prosodically strong positions. Annotation was conducted by the author and subsequently rechecked for internal consistency. No independent or second annotator was used, which should be considered a limitation of the exploratory design.

Earworms rely on distinctiveness and predictability ([8]; [4]). This study proposes that vowel type contributes to distinctiveness at the phonetic level.

The primary statistical corpus consisted of eight songs selected for formal phonetic and prosodic coding. These English-language songs were selected for clearly identifiable lyrical hooks and broad cultural recognition. The sample included works by the Beatles, Queen, Michael Jackson, Pink and Avicii, chosen to capture cross-genre consistency rather than statistical representativeness. Additional songs discussed later in the paper are included illustratively and were not incorporated into the statistical analysis.

One primary lyrical hook per song was analyzed. Hooks were defined as the most recurrent and structurally emphasized lyrical phrase within the commercially released studio recording. Official lyric transcriptions were cross-checked against the recorded vocal performance.

All target phrases were transcribed using standard IPA conventions ([5]). Vowel nuclei were classified as either diphthongs or monophthongs.

A syllable was coded as strong when either lexical stress or metrical prominence was present, with co-occurring stress and metrical emphasis treated as maximally strong. Syllables were classified as strong if they:

•Carried lexical stress

•Aligned with metrically strong beats.

All other syllables were classified as weak.

To support consistent phonetic annotation, a classification scheme was developed grouping vowel nuclei into diphthongal and monophthongal categories. Representative lexical items were used to illustrate each vowel class, based on standard English phonetic realizations ([5]). This scheme was applied during corpus annotation to identify vowel type and distribution across prosodic positions.

The analysis examined the following variables:

•independent variable: vowel type (Diphthong vs. monophthong).

•dependent variable: prosodic position (Strong vs. weak).

Frequencies were aggregated across the corpus and categorized according to vowel type (diphthong vs. monophthong) and prosodic position (strong vs. weak). A consistent pattern was observed across artists.

For example:

•The Beatles—“Hey Jude”

Diphthongs (/eɪ/, /oʊ/) are concentrated in strong positions.

•Queen—“Don’t Stop Me Now”

Diphthongs align with stressed syllables.

•Avicii—“Hey Brother”

The diphthong /eɪ/ in “Hey” occurs in a phrase-initial strong position, while stress patterns in later syllables reinforce structural salience.

Additional informal observations suggest cross-genre consistency in phonetic-prosodic alignment. The expanded corpus further supports the observed distribution of diphthongal salience across artists. For example, in Mika’s Grace Kelly, the diphthong /aɪ/ occurs repeatedly in phrase-final and prosodically strong positions (e.g., “why,” “mind,” “try”), contributing to perceptual prominence. Similarly, Relax, Take It Easy exhibits diphthongs aligned with phrase endings and melodic emphasis.

Comparable illustrative observations in patterns are observed within Lenny Kravitz’s Fly Away, where the hook is constructed around repeated diphthongs (/aɪ/, /eɪ/), and Are You Gonna Go My Way, where diphthongs are concentrated in structurally prominent positions. These observations reinforce the cross-genre distributional tendency for diphthongal nuclei to align with salient structural positions.

Figure 2. Hierarchical Tree diagram model of multi-level salience interactions across phonetic, prosodic, and structural domains.

This suggests that salience emerges through interaction across multiple organizational levels rather than from isolated phonetic features alone (Figure 2).

Figure 3. Taxonomy of phonetic-prosodic reinforcement patterns observed across the corpus.

The taxonomy further indicates that salience patterns vary according to compositional context and structural positioning (Figure 3).

Within this framework, structural units may function analogically to linguistic roles.

•hooks: salience peaks.

•rhyme areas: phonological parallelism.

•transitions: prosodic boundary regions.

•sequences: structural frames.

Salience emerges from the interaction of:

•phonetic structure (vowel dynamics).

•prosodic structure (stress).

•musical structure (song form).

The observed distribution supports the proposal that dynamically complex vowel nuclei are preferentially aligned with perceptually prominent positions. Diphthongs, characterized by internal formant movement, provide a temporally extended and acoustically dynamic signal ([5]). When combined with prosodic stress and musical emphasis, this dynamic structure may enhance perceptual salience.

However, this alignment should not be interpreted as evidence of a purely segmental effect. Rather, the findings point to an interaction between phonetic and prosodic structure, in which diphthongs are situated within already prominent positions, potentially amplifying their perceptual impact.

The results are consistent with broader accounts of musical salience that emphasize the interaction of multiple factors, including repetition, predictability, and distinctiveness ([3]; [8]; [11]). Within this framework, diphthongs may contribute to the distinctiveness dimension, while monophthongs may contribute to stability and fluency.

The findings are consistent with a possible dual-mechanism account.

•diphthongs function as salience peaks due to acoustic dynamism.

•monophthongs provide structural continuity, supporting repetition and processing ease.

Such a balance between variability and predictability has been associated with memory formation and perceptual engagement ([7]).

The case studies demonstrate that diphthongal salience is not limited to a single structural position. While some examples exhibit phrase-final clustering, others show distributed or phrase-initial salience patterns. This variability suggests that phonetic-prosodic alignment operates flexibly across different compositional styles.

Rather than a fixed rule, the data support a taxonomy of salience configurations, including:

•terminal salience peaks.

•initial salience triggers.

•distributed alignment with semantic emphasis.

This reinforces the view that salience is context-dependent and structurally adaptive.

The findings have implications for models of involuntary musical imagery (INMI). While existing research has focused on melodic and rhythmic features, the present study suggests that segmental phonetics may also contribute to memorability by shaping perceptual prominence at the micro-level.

Importantly, the results do not demonstrate that diphthongs cause earworms. Rather, they indicate that phonetic features may function as supporting mechanisms within a broader system, interacting with repetition, rhythm, and melodic contour.

Several limitations must be acknowledged. First, the dataset is relatively small and non-random, limiting generalizability. Second, the classification of prosodic strength involves a degree of interpretive judgment, despite efforts to maintain consistency. Third, the present analysis does not experimentally isolate the perceptual effects of diphthongs.

Future research should therefore:

•expand the corpus across genres and languages.

•incorporate acoustic measurements of vowel dynamics.

•conduct perceptual experiments to test listener responses.

•explore computational models of salience and expectation.

•investigate whether systematic vowel placement can enhance mnemonic retention.

Taken together, the findings indicate that phonetic detail—specifically vowel dynamics—plays a structured role in the organization of perceptual salience in musical hooks. By integrating segmental phonetics into models of musical cognition, the study provides a basis for further investigation into the interaction between language and music at both acoustic and cognitive levels.