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Screenshots

  • TGSpeechBox screenshot 1
  • TGSpeechBox screenshot 2

About TGSpeechBox

TGSpeechBox is a high-quality speech synthesizer that works as a system voice with VoiceOver and as a standalone text-to-speech app. Features: • 26 languages with natural-sounding speech • Full VoiceOver integration — use as your primary system voice • 7 voice presets plus YAML-defined voice profiles • Deep engine tuning: pitch mode, voice tone, formant sharpness, inflection, tremor, breathiness, and more • Phoneme editor: fine-tune individual speech sounds with live preview • Pronunciation dictionary: add custom word pronunciations with IPA override support • Stress, compound, and character dictionaries for advanced control • Export and share your customizations • Adjustable sample rate (11025–44100 Hz) • Rate override and rate boost for VoiceOver • Language lock: keep your preferred language regardless of system setting • Runs entirely on-device — no internet required, no data leaves your phone TGSpeechBox uses a Klatt-style formant synthesis engine with eSpeak-ng for phoneme generation. It is open source under the MIT license. Built by a blind developer, designed for accessibility from day one.

What’s new

Version 3.0.1 · Updated April 3, 2026

This version adds many new features: - Higher cascade formants F7 (6500 Hz) and F8 (7500 Hz) for spectral presence above F6 (Rabiner 1968 defaults). Nyquist-proximity fade auto-mutes them at low sample rates. - Parallel F7/F8 resonators for fricative high-frequency presence (amp 0.15/0.07). - 2x source oversampling for cleaner harmonics at lower sample rates. - Dual-oscillator chorus for vocal fold asymmetry (VoicingTone V5): chorus depth and variation sliders for natural vocal fold jitter. - Brown noise aspiration blend: white/brown noise mix by sample rate (44k=100% white, 22k=70/30, 16k=50/50). Fixes aspiration thinness at lower sample rates. - Glottal sharpness rebalanced for F7/F8 spectral dynamics. - Transition bandwidth widening after obstruents: decaying BW boost across first 3 micro-frames, scaled by F2 sweep width. - Word-final stop audibility improved: stop floor 4ms to 6ms, word-final bonus 5ms to 8ms, voiced alveolar softening eased. - Voiced consonant bandwidths widened for smoother transitions. - Rhotic diphthong collapse: vowel+liquid tied pairs (/ER/ in "shared", "scared", "stairs") now collapse into micro-frame diphthongs with proper formant sweep. Previously rendered as two crushed tokens with no glide. - SQUARE diphthong pairScale 1.40 for the wide F3 sweep (2500 to 1620 Hz). - Diphthong rate compensation bumped 0.15 to 0.30; onset hold exponent 1.3 to 1.6 for better vowel identity at high rates. - Fixed diphthong tie bar blocking dialect replacements: eSpeak marks diphthongs with tie bars (e-tied-I) which blocked I-to-I_es substitution. Vowel-vowel tie bars are now stripped early; affricate tie bars preserved. (issue #82, reported by @gregodejesus2) - New `I_es` parallel formants tuned to Spanish-peripheral [i] target (Quilis 1981, Martinez Celdran): pf1 330, pf2 2150, pf3 2850. Previously carried English-lax values. - New `U_es` phoneme for Spanish [u] diphthong offglides (/au/, /eu/): F1=340, F2=780. Base /U/ was English-lax (F1=405, F2=900). - `autoDiphthongOffglideToSemivowel: false` for Spanish to preserve dialect-specific offglide phonemes. - Geminate /ss/ deduplication from eSpeak number expansion ("200" no longer "dosssientos"). - Fixed "behind a wall" quality at 22050 Hz: disabled oversampling decimation and anti-alias LP at 22050+ Hz. Sharpness raised 2.0 to 3.0. This was the most-reported audio quality issue since v3.0.

App privacy

The developer, Tamas Geczy, reported these privacy practices to Apple.

Data Not Collected

The developer does not collect any data from this app.

Alternatives to TGSpeechBox

Looking for apps like TGSpeechBox? Here are 6 similar apps on the App Store. The highest rated is ToBe SAID: Offline TTS Engine (5.0/5), and 5 of the 6 are free to download.

TGSpeechBox vs. alternatives
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