Vowel Synth

Explore how resonant frequencies shape vowel sounds. The synth sends a selectable sound source through three parallel band-pass filters: F1 and F2 carry most of the vowel identity, while F3 adds colour. Its default glottal-style source has a softer harmonic roll-off than a saw wave, and the brightness control adjusts its upper spectrum.

The switch provides steady monophthong presets for Received Pronunciation, General American, Mandarin and Japanese, all labelled with IPA. The English presets also use Wells lexical-set keywords, the Mandarin set pairs each target with an example character and unmarked pinyin, and the Japanese set shows the five kana vowels. Their filter values are illustrative starting points; real values vary between speakers, regions and generations. The RP positions are informed by Bjelaković’s measurements of contemporary BBC newsreaders  and Hawkins and Midgley’s study of age-related differences ; the General American positions use the adult male averages in Peterson and Barney’s vowel study , the Mandarin set uses male-speaker means from Meng, Chen and Li’s statistical survey , and the Japanese set uses the synthetic-vowel values reported by de Cheveigné and colleagues .

The Mandarin set covers seven steady oral targets: /a o ɤ ɛ i u y/. 哦 is used as the isolated /o/ example; ordinary bo, po, mo, and fo contain the uo rhyme despite omitting the u in pinyin spelling. Tones, compound finals and the two sibilant-following -i finals are omitted because they need pitch movement, moving formants or a different source spectrum.

Whisper/noise excites all three filters without a pitch. Sine is kept as a test source: because it has no harmonics, it demonstrates that the formant filters reshape frequencies already present in the source.

Diphthong lexical sets are omitted for now because they need moving F1/F2 trajectories rather than one fixed filter position.

The pitch control also includes 12-TET approximations of C gōng (C D E G A) and C hirajōshi (C D E♭ G A♭) pentatonic note sets. Gōng is one of several Chinese pentatonic modes, and hirajōshi is a Japanese koto tuning rather than a universal national scale.