December 2, 2013 at 6:05 pm

CanOpener Improves iPhone Sound Quality for $4 Using Actual Science

Well, we might have just found the grandaddy of all audiophile music apps, perfect for the most important music snob in your life: you.

Of course, if you care about sound quality, you already have nice headphones.

Canopener for iOS ($4, or $1 today), is about what happens right before the sound leaves your iPhone, before it gets to your “ear goggles.” It’s a music player app, meaning that its developer, Good Hertz, is hoping you’ll use it instead of Apple’s own Music app. This also means it doesn’t work with streaming music or subscription services — just your own downloads. Other than that nitpick, quite honestly, we cannot think of a single reason you wouldn’t want this app, if you listen on iOS and care about sound quality.

It looks good. Great design. But that’s not what this app is for. Luckily, Good Hertz LLC, the company behind this app, whose founder, owner, and lead developer Devin Kerr is a mad audio scientist, producer, musician, and sound engineer who really knows what he’s doing.

This app almost does too many things for us to mention, but we’ll try, below. To summarize its appeal: This is the iOS sound quality app for people who don’t believe in lots of weird, fanciful processing to add “space” to a sound. CanOpener‘s approach is anythiung but snake oil — it’s science.

The most basic thing this app does is add crosstalk to your headphones — as much or as little as you want. Crosstalk is what makes speakers sound different from headphones, because a little bit of the left speaker gets to your right ear, and a little bit of the right speaker gets to your left ear — thus the term “crosstalk.” Normally, headphones eliminate all crosstalk; CanOpener puts it back, which you can’t hear in this blog post, but the control looks like this:

Meanwhile, a “mastering-grade baxandall equalizer” lets you sculpt sound right from the spectrogram. First you see the sound:

Then you sculpt it with your fingers:

Or choose a preset:

CanOpener also tracks your current SPL (sound pressure level, more commonly known as volume), as well as your lifetime average SPL, and the number of minutes of music you have listened to in the app:

Devin Kerr, musician, designer, and owner/developer of Good Hertz, tells that he’s noticed some interesting patterns in how people are using the app so far.

“We haven’t completed any formal data analysis yet, but one thing we are very pleased with so far with is the average listening level that most of our users are using CanOpener at,” said Kerr via email. “Only around 10 percent of our users have average listening levels over 85 dB SPL (which is the generally accepted threshold where hearing damage is possible), and the highest percentage of our users have average listening levels between 65 and 75 dB SPL, which we consider ideal. At least preliminarily, this data suggests that when using CanOpener’s Dosimeter, users may be more aware of their listening levels and thus choose healthier volumes.”

Moving on, you can choose your headphones in the app to make sure it’s controlling the settings properly for your model. If yours aren’t included, you can dig up the specs and add them to the app manually:

This is the first music app we have seen, we think, that includes a bibliography citing the sources upon which its science is based:


CanOpener does all of this and more, but one thing it does not do is apply some weird “spatializer” algorithm or whatever to all of your music, the way many apps that purport to improve sound quality do.

We’re a bit late with this story, because CanOpener is on sale until… today, Monday, December 2, 2013. However, we’d still consider it worth the money even without the discounted price, if you A) listen to lots of downloaded music on your iPhone or iPod Touch, and B) care about sound quality in a somewhat scientific way.

  • Gahe

    Very useful and supportive article. I wish I can do all of that in a short period of time.

  • Anonymous

    This app’s effect is far too subtle to be of much value on my iPod Touch 4g 6.1.5. I hear little to no change at all between “bypass” and “on” whatever the settings might be. When EarBuds are selected, the equalizer is set to boost the high end which is patently ridiculous for EarBuds which have so little bass.

    Only working, if it did, on music stored in the phone and not on anything from streaming apps like Rhapsody, Amazon, Pandora, Google, and iTunes is much more than a nit. Such services have completely replaced music stored on the phone for me.

    OTOH, Apple makes it impossible to do it any other way. There is simply no way to process the audio output stream on iOS by design. Hell, one might then record streams with an app designed to do so. (Like you can on Windows trivially with Total Audio Recorder.) An app designer’s only option is to make a player for phone stored music and create that processed output stream like these guys did. Android has similar issues but can be hacked.

    There _is_ an app that should be integrated one’s like this, however. WiFi2HiFi allows you to play anything you can stream to WiFi from a desktop which is about anything.