Driven by a passion to democratize hearing enhancement technology, I conceived and championed the Personal Sound Amplifier (PSA) app for Android. After securing support from Google’s accessibility team, I spearheaded its development.
I managed to secure cross-functional collaboration with research, android, product and google health teams; and created the first prototypes of the android app, including the core DSP algorithms and code involved in a hearing-enhancement application.
I managed to convince the execs that instead of burying the DSP algorithms inside of a single PSA app, we could generalize them as part of the Android OS for other applications to use. This in turn became its own project called Dynamics Processing Effect, which is also at the core of another one of my key projects: Pixel Adaptive Sound.
My key design principle for this DSP library was to define a very flexible API to set and control the audio effect, and offer a very high quality default implementation. This opened the door for OEMs to either offer their own software implementation, or even one that made use of hardware acceleration and improved the performance for that particular family of devices.
This approach had the good side effect that even older devices will have access to this library, and thus developers could make good use of it in their apps, in more devices all over the world.
This design significantly expanded the reach of PSA, particularly in regions with limited access to hearing enhancement technology and where the cost of dedicated devices is prohibitive.
I led the team that did the development and productization of PSA.
Sound Amplifier was launched in 2018, and I presented its development and impact at Google I/O 2018 and 2019.
Google I/O 2018:
Google I/O 2019:
I authored an invited post on the Google Blog, detailing how Sound Amplifier leverages machine learning and accessibility principles to improve hearing clarity for millions of Android users.
Some interesting numbers and publications:
Sound Amplifier has achieved over 100 million installs to date, with a growth of over 400,000 new installs per month (as of 2025)
This is me showcasing Sound Amplifier in action alongside my Hearing Loss simulator, and people trying it and recommending it:
I contributed to the publication “Auditory Measures for the Next Billion Users” in Ear and Hearing, collaborating with leading figures in audio and internet technology, including Vint Cerf, Dick Lyon and Malcolm Slaney and Brian Kemler
Thanks for reading!
-Ricardo (rago)