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ams acoustic reference design for noise-cancelling earbuds

Bonsai earbuds and the ams Augmented Hearing app show how well the Adaptive Leakage Compensation (ALC) technology adapts to the constant changes in noise which leak into the ear when wearing loose-fit earbuds.

Earbud manufacturers have been wrestling with a puzzle which has appeared impossible to solve. The way that consumers use earbuds means that noise cancellation is a highly desirable feature. People want to be able to use their earbuds on noisy city streets, inside underground metro trains, in a busy office – and they want to hear their music, not the ambient noise of traffic, machinery or chatter.

The easiest way to make earbuds block noise is to shape them so that they plug tightly into the ear. This enables the earbud’s silicone tip to make a physical barrier against sound waves from outside the ear. Combined with a high-performance Active Noise Cancellation (ANC) system, this type of earbud can achieve very high levels of noise attenuation, and provide an almost perfectly silent aural background for the listener’s music or other audio content.

But tight-fitting earbuds can be uncomfortable to wear for long periods – and some users want to wear their earbuds all day long.

So the loose-fit earbud was developed, offering a much more comfortable feel for all-day wear – but of course the gap between the ear and the tip of the earbud allows noise from outside to ‘leak’ into the ear. And this leakage is a dynamic phenomenon: the frequency and amplitude of the noise which leaks into the air continually changes as the earbud shifts its position in the ear, slightly opening up or closing the gap each time between ear and earbud.
 

The audio Catch-22: comfort or noise attenuation

So here is the conundrum: earbud wearers have been offered either comfort, or effective noise attenuation – but not both in one product. Until now. 
The world’s most successful pioneer of advanced noise cancellation technology, ams has made another breakthrough, this time in noise cancellation for loose-fit earbuds. Its Automatic Leakage Compensation (ALC) technology continuously and automatically adjusts the filtering operation and amplifier output from the ams AS3460 Digital Augmented Hearing engine (an advanced ANC chip), to match in real time the frequency profile and amplitude of the noise which leaks into the ear.

Wearing loose-fit earbuds based on the AS3460 with ALC technology is a revelation: comfortable of course – but providing up to -35dB of noise attenuation, at least 25dB better than any loose-fit earbuds on the market in 2020.

There’s more: when using loose-fit earbuds with ALC technology, the wearer’s voice sounds natural, there are no pops or clicks spoiling the sound effect, and music quality is unaffected.
 

Hear the difference in the new ams reference design

And you do not have to take my word for it: ams has now produced a complete ALC acoustic reference design which earbud manufacturers can use to evaluate the performance of ams’ ALC technology out-of-the-box.

The Bonsai reference design is supplied as a complete audio system including an Android OS-based smartphone with an Augmented Hearing app developed by ams. You simply turn on the phone, power on the charged earbuds, open the app, and start listening comfortably to the music stored in the phone – with almost no audible outside noise.

The Bonsai kit provides a complete acoustic reference design based on a typical loose-fit form factor. The design provided by ams includes a battery power source mounted in the stalk of the earbud, a dynamic speaker, microphones for the user’s voice and for the ANC function, and infrared proximity sensors for gesture control of key audio functions.

The noise attenuation achieved by the Bonsai earbuds is truly impressive. This graph shows the noise attenuation provided by the Bonsai earbuds when exposed to high or low leakage:



 

The graphs tell a clear story, but the effect of the ams ALC technology has to be heard to be believed. And now that ams has created a comprehensive acoustic reference design, this miracle of sound engineering can be quickly and easily implemented by any earbud manufacturer, with help from ams’ audio technology specialists.

The first step in designing loose-fit earbuds with ALC technology is to evaluate the performance of the Bonsai earbuds.