{
  "id": 1500675,
  "title": "Why Your Generated Tone Clicks, and How an Envelope Fixes It",
  "url": "https://urgent.news/2026/08/17/why-your-generated-tone-clicks-and-how-an-envelope-fixes-it",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-08-17T14:57:57.000Z",
  "source": {
    "name": "Dev.to",
    "slug": "dev-to",
    "url": "https://dev.to/mwiginton/why-your-generated-tone-clicks-and-how-an-envelope-fixes-it-1p89"
  },
  "original_language": "en",
  "account": "When you generate a pure tone in code and play it back, you may have observed a small click at the beginning or end of the sound. This click is not a bug in the sine wave itself, but rather a well-understood artifact that can be fixed using an envelope. An envelope is a technique that smooths the transition of a sound by gradually increasing and decreasing its volume, rather than having sudden jumps.\n\nA tone is essentially a list of samples that trace a sine wave. When a speaker reproduces the tone, it moves based on the sample values, with 0 being the resting position and larger values pushing it forward or pulling it back. At the playback start, the speaker cone is at rest. However, the first sample of the tone is often not at 0. If the first sample is far from zero, the speaker cone has to move from rest to that position in a single sample, resulting in a sudden jump that creates a click.\n\nThis phenomenon is easily visible in the sample values. For a 440 Hz tone at half amplitude, the first six samples are: n=0 raw=0, n=1 raw=1026, n=2 raw=2048, and so on. As the wave leaves zero and climbs, the signal jumps by 1026 in one step. The same abrupt change occurs at the end of the tone if it stops while the wave is halfway through a cycle. In this case, the signal drops from a large value straight to silence, creating another click.\n\nTo eliminate these clicks, an envelope can be applied to the sound. The envelope is essentially another set of numbers, ranging from 0.0 to 1.0, that you multiply with each sample. Initially, the envelope is 0.0, so the output is silent. It then gradually rises to 1.0, allowing the wave to reach full volume. The envelope holds at 1.0 through the middle of the tone and then falls back to 0.0 towards the end. The rising part is called the attack, and the falling part is called the release.\n\nImplementing an envelope in plain C++ is straightforward. In the tone loop from a previous article, an extra gain factor is added. For each sample, the wave is computed as usual, and then a gain is calculated based on the position of the sample within the tone. The gain is set to 1.0 by default, but within the attack region, it rises from 0.0 to 1.0, and within the release region, it falls from 1.0 to 0.0. The rest of the time, the gain remains at 1.0, leaving the wave untouched.\n\nThe results of applying an envelope are clear. The initial jump from silence to the first sample is reduced from 1026 to 2, effectively eliminating the click. The ending click is also smoothed out, with the tone fading gently to silence instead of dropping off abruptly. Importantly, the pitch remains unchanged, as the frequency analysis of the enveloped tone still reads a dominant frequency of 440 Hz. The loudness is also preserved in the middle, with the peak sample value still at 16383, exactly half the amplitude requested.\n\nThis technique of using envelopes to smooth the edges of generated tones is not just about removing clicks; it is a fundamental concept in sound synthesis. Different sounds, like a plucked string or an organ note, have distinct volume profiles based on their attack and release characteristics. By controlling the envelope, you can shape the volume over time, creating the unique timbre of various instruments. Envelopes are a simple yet powerful tool in sound design, allowing you to craft realistic and recognizable sounds by manipulating their attack, decay, sustain, and release (ADSR) characteristics.",
  "summary": "If you have generated a pure tone in code and played it back, you may have noticed a small click at the start, the end, or both. The tone itself is clean, but the edges are not. That click is not a bug in your sine wave. It is a real and well understood artifact, and the fix is a technique you will reuse in every sound you ever synthesize: an envelope. This piece builds directly on generating a…",
  "key_points": [
    "Click at tone start and end due to sudden volume jump",
    "Envelope technique smooths volume transition",
    "Attack and release regions shape sound timbre"
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}