Pitch
Correction and shifting toward selected musical notes
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Synthphone-E
A real-time vocal-effects processor, synthesizer, and MIDI instrument built inside an old telephone.
The handset's original speaker is used in reverse as a deliberately lo-fi microphone. A Daisy Seed inside the phone handles the audio processing, synthesis, controls, and display.
How a microphone became Synthphone-E.
01Speak into a telephone handset speaker
02Use a thrift-store phone as the enclosure
03Give the unused buttons a synthesizer
04Add real-time vocal processing
05Keep adding modes instead of stopping
The phone has profiles now.
The firmware has grown since the 2025 build video. These are the modes running on the current prototype.
Formant
Preservation and deliberate vocal-character changes
Vocoder
Voice-shaped synthesis from a harmonically rich carrier
Harmony
Multiple MIDI-controlled target frequencies
Texture
Bit-depth and sample-rate reduction
Instrument
MIDI synthesis, percussion, keypad controls, and OLED menus
The voice goes in. Math happens.
Audio moves through overlapping windows so frequency-domain effects can run continuously without stopping the real-time input and output path.
HandsetLo-fi speaker transducer
→ 48 kHzContinuous ring buffer
→ FFTOverlapping audio windows
→ DSPPitch / formant / vocode
→ AudioReconstructed in real time
Pitch correction
Moves the detected voice toward a musical note without changing playback speed.
Formants
Preserve or alter the resonant character of the voice separately from pitch.
Vocoding
Applies the changing spectral shape of the voice to a synthesized carrier.