Tutorial · Beginner · 5 min

Making sound

Turn signals into sound: tones, chords, envelopes and stereo — and save them as WAV files.

1. A tone

   sound(y, fs) plays the samples y (between −1 and 1) at fs samples per second. A player with the waveform appears under the figure.

   fs = 44100;
   t = 0:1/fs:1;
   sound(0.4*sin(2*pi*440*t), fs)    % concert A

   Try it ↗

2. A chord with an envelope

   Add tones together and shape the loudness over time. soundsc scales the result so it is as loud as possible without clipping.

   fs = 44100; t = 0:1/fs:2;
   chord = sin(2*pi*261.6*t) + sin(2*pi*329.6*t) + sin(2*pi*392*t);   % C major
   env = min(t/0.02, 1) .* exp(-1.5*t);
   soundsc(chord .* env, fs)
   plot(t, chord .* env), xlabel('time (s)'), title('C major chord')

   Try it ↗

3. Stereo and saving

   A matrix with two columns is played in stereo (left, right). audiowrite offers the result as a WAV download.

   fs = 22050; t = (0:1/fs:3)';
   left = sin(2*pi*300*t); right = sin(2*pi*303*t);    % slightly detuned: a slow wobble
   audiowrite('wobble.wav', 0.4*[left right], fs)
   sound(0.4*[left right], fs)

   Try it ↗