# audio/tone Synthesize and play a tone (stereo S16 at 44.1 kHz) through the shared playback device. ## Syntax

[audio/tone ?$freq ?$dur ?$opts]

## Parameters - `freq` — frequency in Hz (optional, default 880; values ≤0.1 fall back to 440) - `dur` — duration in seconds, must be in (0, 60] (optional, default 0.1) - `:wave` — `:sine` (default), `:square`, `:triangle`, `:saw`, `:noise` (unknown names fall back to `:sine`) - `:volume` — gain, clamped to 0.0–4.0 (optional, default 1.0) - `:attack` / `:release` — envelope seconds, clamped to `dur` (optional, defaults 0.005 / 0.02) ## Examples

set v [audio/tone 880 0.1 %{ :wave :square :volume 0.4 }]
[audio/tone 220 1.5 %{ :wave :saw :attack 0.1 :release 0.5 }]

## Returns Voice id (number). `%Err{:message}` when no SDL host is compiled in, `dur` is outside (0, 60], the device is unavailable, or synthesis/voice start fails. ## See Also `audio/beep`, `audio/play`, `audio/stop`