---
title: Synthesis
description: "Synth voices shaped by an envelope, the ramps that shape them, and drum hits made from oscillators and noise."
---

## Synth voices

```bash
npx shadcn@latest add @audio-ui/use-synth-voices
```

`useSynthVoices` plays notes on a pool of voices, one per held pitch: an oscillator through a gain shaped by an envelope. The attack and the decay play when the note starts and hold at the sustain level; the release plays when it ends.

```tsx
import { useMasterBus } from "@/hooks/use-master-bus";
import { useSynthVoices } from "@/hooks/use-synth-voices";

const output = useMasterBus(0.7);
const voices = useSynthVoices({ destination: output, oscillatorType: "triangle" });

<Piano
  onNoteOff={(pitch) => voices.releaseNote(pitch, envelope)}
  onNoteOn={(pitch) => voices.triggerNote(pitch, envelope)}
/>;
```

`envelope` is the points of an [Envelope](/docs/components/base/envelope), `{ x, y }` from 0 to 1, so the shape a user draws is the shape the note plays: the points before the middle (`x` 0.5) are the attack and the decay, the points after it the release. Give `time` to `triggerNote` and `releaseNote` to schedule a note ahead, as a [transport clock](/docs/engine/clock-and-time) does; leave it out to play now.

<TypeTable title="Options">
<TypeRow name={"destination"} type={"AudioNode | null"}>Where the voices play, such as the master bus.</TypeRow>
<TypeRow name={"oscillatorType"} type={"OscillatorType"} default={"\"sawtooth\""}>The waveform: `"sine"`, `"triangle"`, `"sawtooth"` or `"square"`.</TypeRow>
<TypeRow name={"attackDecaySeconds"} type={"number"} default={"0.4"}>How long the first half of the envelope lasts.</TypeRow>
<TypeRow name={"releaseSeconds"} type={"number"} default={"0.3"}>How long the second half lasts.</TypeRow>
<TypeRow name={"peakGain"} type={"number"} default={"0.25"}>A voice's gain at the top of the envelope, at full velocity.</TypeRow>
</TypeTable>

<TypeTable title="Returns">
<TypeRow name={"triggerNote"} type={"(pitch, envelope, velocity?, time?) => void"}>Starts a voice. `velocity` is 0 to 1. No-op if the pitch already sounds.</TypeRow>
<TypeRow name={"releaseNote"} type={"(pitch, envelope, time?) => void"}>Plays the release and stops the voice.</TypeRow>
<TypeRow name={"releaseAll"} type={"() => void"}>Stops every voice at once: on stop, on a seek, on unmount.</TypeRow>
<TypeRow name={"setPitchBend"} type={"(semitones) => void"}>Retunes every voice, as a pitch bend wheel does. 0 is back to pitch.</TypeRow>
</TypeTable>

## Envelope ramps

```bash
npx shadcn@latest add @audio-ui/envelope-ramp
```

The ramps behind the voices, for your own sounds: `scheduleEnvelopeRamp(param, points, startTime, seconds, peak, from)` runs a gain through an envelope's points, and `sliceEnvelope(points, fromX, toX)` takes a part of one, such as the release after `SUSTAIN_SPLIT_X`. A ramp cancels what was scheduled on the param first, so starting a note again never clicks.

## Drum hits

```bash
npx shadcn@latest add @audio-ui/drum-synthesis
```

A kick, a snare and a hihat made from oscillators and noise, with no samples to load. Each starts at `time` and plays out on its own.

```tsx
import { triggerHihat, triggerKick, triggerSnare } from "@/lib/drum-synthesis";

triggerKick(ctx, output, time);
triggerSnare(ctx, output, time, { tune: 2 });
triggerHihat(ctx, output, time, { decay: 0.5 }); // a longer decay rings open
```

`tune` shifts a hit in semitones from its own pitch and `decay` sets how long it lasts, in seconds. The [Pad](/docs/components/base/pad) page plays a kit with them.