Creating an Oscillator with Web Audio API

 Have you ever wanted to create your own audio effects or musical instruments in your web app? Look no further than the Web Audio API! As technology continues to advance, it becomes easier to create custom web-based applications with interactive features. One of the ways to enhance user experience is by incorporating audio effects into your web app. In this tutorial, we'll explore the Web Audio API, which allows you to manipulate audio with JavaScript. We'll focus on creating a basic oscillator that can be triggered by a user event like a mouse click. By the end of this tutorial, you'll have a good foundation to build more complex audio effects for your web app.

Why Web Audio API for Electronics Engineers?

The Web Audio API provides a powerful toolset for electronics audio engineers working in web development. With the ability to create, manipulate, and play audio signals directly in the browser, the Web Audio API provides a level of flexibility and control that was previously not possible in web audio. This can be especially useful for audio engineers who want to create web-based audio applications or interactive audio experiences, as it allows for precise control over audio signals and effects. Additionally, the Web Audio API provides a way to create real-time audio processing, which can be useful for audio analysis, synthesis, and effects. Overall, the Web Audio API provides a valuable connection between electronics audio engineering and web development, allowing for the creation of powerful audio applications that can be used on a wide range of devices.

Following is a JavaScript program that utilizes Web Audio API to play sinusoidal wave when user clicks on a webpage like this web page.

const ctx = new AudioContext;
    let osc;

    function playOsc(oscType, freq){
            osc = undefined;
            osc = ctx.createOscillator();
            osc.type = oscType;
            osc.frequency.value = freq;


The above code creates a function playOsc which takes two arguments - the oscillator type and frequency. It also creates an AudioContext object and a variable osc that will be used to store the oscillator object.

Inside the playOsc function, it first checks if the oscillator object exists, and if it does, it stops the oscillator by calling the stop method of the AudioContext object and sets the osc variable to undefined. If it doesn't exist, it creates a new oscillator using the createOscillator method of the AudioContext object, sets the oscillator's type and frequency, connects it to the AudioContext's destination, and starts the oscillator using the start method.

The code then adds an event listener to the mousedown event on the document object, which when triggered, calls the playOsc function with a sine wave oscillator type and a frequency of 330.

Overall, the code creates an oscillator using the Web Audio API, and sets up an event listener to play the oscillator when the mouse is clicked. The code can be used as a starting point to create more complex audio effects using the Web Audio API.

In conclusion, the Web Audio API provides a powerful way to create custom audio effects for your web app. In this JavaScript tutorial for electronic engineers, the basics of the Audio Web API was explained and it was illustrated how to use JavaScript to create a simple oscillator that can be triggered by user events like a mouse click. By using JavaScript to manipulate the API's nodes, you can create a variety of sounds and effects that can enhance the user experience. Whether you're creating a game, a music app, or a podcast player, the Web Audio API is a valuable tool to have in your web development toolkit.

References and Further Readings

[1] Web Audio API createGain and GainNode

[2] Web Audio API Volume Control with Gain Slider

[3] Filters with Audio Web API 

[4] Web Audio API : Visualizing Frequency Response


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