Accessibility First

Our mission in building Dwell is to help others cultivate a habit of listening to the most important book in history: the Bible.

For most of us, the idea of listening to scripture is a new one. Christianity is a reading-centric culture, and for good reason. The ability to read and study the word of God for yourself is a priceless gift. We’re working to augment the experience of seeing God’s word, not replace it.

But, what if you can’t see God’s word?

All across the globe tens of millions of people struggle with visual impairment. If the US alone 8,000,000 people fight with limited or no vision, including nearly 700,000 children. For these brothers and sisters, listening to God’s word is not a preference, it’s all there is.

For these brothers and sisters, listening to God’s word is not a preference, it’s all there is.

As we build Dwell, we’re committed to ensuring that everyone who can use a smartphone can listen to God’s word from Day one.

That’s nice, you might think, but if you’re blind how can you use a smartphone at all?

Well, thanks to the engineers at Apple, it’s not only possible to use an iPhone while blind, it’s possible to thrive on an iPhone.

Apple provides two main technologies to help the visually impaired: Dynamic Type and Voiceover.


Dynamic Type allows a user to set the base font-size across the entire phone. By taking this setting into account, 3rd party apps like Dwell can adjust the font sizes in their apps to be larger (or smaller), easing the struggle for those with aging eyes, among other ailments. We’re designing Dwell’s UI to support Dynamic Type in as many areas as possible. It might seem like a small thing, but to someone who struggles to read small text it can be the difference between being able to use an app or having to set it down and move on.

Voiceover allows even those with no vision at all to navigate through apps.

If you’ve never seen voiceover in use, let me encourage you to watch this video demonstration. It really is amazing to see how proficient the visually impaired can be with an iPhone, and how life-changing the experience can be.


By leveraging the tools that Apple has built we are able to provide descriptions and hints to the various controls across the Dwell app, enabling Voiceover users to hear the descriptions as they move through the app. It’s a limited amount of extra work for us, and it opens up the entirety of God’s word to our listeners.

With Dwell, accessibility isn’t “Coming Soon,” it’s here now. We’re building for Accessibility First.

Jeff McFadden
Slicing and Dicing

As we covered last time, the Bible is a big book. Once we’ve recorded all of our audio, we’ll still need to get those 177+ gigabytes of data onto a smart phone, and potentially all delivered over a slow 3G network. How on earth will we be able to do that?

The solution is to slice up the audio into the pieces we need, stitch them together, and send just that little chunk of data to the phone.

Let’s take a hypothetical listening plan as an example. We’ll call it Nuggets of Wisdom. Each day will include a few verses on a related topic, pulled from across scripture. Here’s what Day 1 looks like:

Day 1: “Faith”. Hebrews 11:1, Romans 1:17, Mark 9:24, Mark 5:36, 2 Timothy 4:7

(A listening plan that was actually this scattershot would probably be terrible, but it’s a helpful example, so let’s go with it.)

Looking at the verses for this day of the plan, we’ll need some of the audio from five chapters: Hebrews 1, Romans 1, Mark 9, Mark 5, and 2 Timothy 4. We have the recordings for each of those, but how will we extract only the verses we need? We’re going to need to know where each verse starts and ends within the audio of the full chapter. For that, we’re going to need another tool.

Enter the Verse Offset Marker Editor

Using this tool we are able to create a marker for each verse boundary in a chapter, and save that data to our growing database.


This means we have to set these markers for every chapter in the Bible, read by every voice artist. It’s a lot of work, but it makes our entire platform possible.

Once we have that data saved for the chapters we need, we can then use our audio toolchain to extract just the portion that we need from each Master Recording, then stitch them all together into a single file. We use a tool called sox to do this.

So now we have just one big wav file with all of our audio slices spliced together. But it’s still too big. We need to make it smaller. This is where our old friend mp3 comes into play. We convert the audio file from wav to mp3, and store it on our servers.


Now, when a listener is ready to hear the listening plan for Day 1, all they have to download is a small audio snippet for that morning, easily downloadable on even a slow 3G network.

Just like the old proverb, How do you eat an elephant? One bite at a time.

Jeff McFadden
That's a lot of Audio

The Bible is a big book. With 1,189 chapters, it takes 4,200 minutes to read it aloud. At Dwell, we're recording each of these 4,200 minutes four times, once with each of our talented voice artists (with more to come)!

Once these raw recordings have been created our talented editors and producers clean up the audio, pulling together the best parts of each take, and mix it down into one single Master Recording.

Each Master Recording is one chapter of the Bible. With 1,189 chapters and four voice artists, we have 4,756 Master Recording files that we need to store and manipulate.

This isn't just a lot of files, it's a huge amount of data. Our Master Recordings are mixed down to 24bit stereo wav files (44.1 kHz sampling rate). An audio file in this format takes up about 950 megabytes of data per hour. All told, that ends up at about 44.5 gigabytes per artist, or 177.8 gigabytes total (with a lot more to come).

The problem that we are faced with is this: How do we upload, store, manage, and deliver 180 GB of audio data to listeners all over the world?

Like any large problem, the solution is to break it up into smaller problems, and solve each of those.

Each Master Recording represents a single chapter of the Bible, which means that the average file is about 75MB. While still large, these are files of a size we can handle.

We take each Master Recording, and upload it to our API server (we'll talk more about our API server in future articles). The API server handles marshalling the data to S3, Amazon's data hosting service, where our files are stored with 99.999999999% durability (this means we should expect to lose a file once every 10,000,000 years; hopefully that's good enough).

By breaking 44.5 GB per artist down into 1,189 individual recordings, and taking each of those and hosting them with a data service provider like Amazon, we start to have the pieces in place to deliver audio to our listeners using our app.

The next problem we need to solve is how to take a Master Recording that's 75MB per chapter and break it up into the smaller chunks (of smaller file size) so that we can deliver it to listeners with even the slowest internet connections.

How do we do that? Stay tuned, as that's what we'll cover next time.

Jeff McFaddenAudio, Development
This Listening Life

Israel grew up listening to Scripture. “Hear O Israel, the Lord our God, the Lord is one.”(Deuteronomy 6:4) Hear. Listen. Allow the words to enter your soul through your ears. Before any of Israel’s great stories of faith and formation were put on paper, they were spoken and heard in the form of narratives, parables, and sayings. Their’s was a listening life. We’ve lost that I think. Those moments where we hear God’s word read over us, where the words ring out in the sky or around the sanctuary or through the miniature speakers aimed at our eardrum. This listening life, a life committed to soaking in Scripture, is what we ought to recover. The spiritual practice of Scripture listening is not just significant because our Christian ancestors did it, it’s significant because Scripture listening forms us in ways that Scripture reading can’t. Listening should not make us diminish the practice of reading Scripture one bit – it’s crucial. It’s absolutely essential for us to understand what the Bible means. I like the way Martin Luther put it, “If you picture the Bible to be a mighty tree and every word a little branch, I have shaken every one of these branches because I wanted to know what it was and what it meant.” Gaining Biblical understanding through reading is foundational, but what I want to draw our attention to is the lost art of listening to Scripture.

The Uniqueness of Reading and Listening

So how do reading and listening shape us in different ways. Let’s take them one at a time. When we read, our default tendency is to study, we want to pull the text apart and piece it back together, we draw conclusions, make decisions, we put the text to work. We’re seeking comprehension. This means we’re searching to grasp with the mind, to sharpen our thinking, to gather, to learn, and above all, to understand. When we read, we want to get something out of it. When we listen, we have to leave all that behind. We lose our ability to be precise, there’s no underlining, cross-referencing, consulting commentaries, starring, or highlighting. Listening is more leisurely. When we listen, our default tendency is to marinate. Instead of reading the words, we steep in them. When we listen we’re gaining apprehension. That means we’re laying hold of something, or better said, something is laying hold of us. We’re seized, captured, engaged and engrossed. It’s similar to what happens to us when we listen to music. We get lost, we’re caught up in it. Scripture listening seeks to put our hearts in a position to simply soak in the Word. In essence, when we listen to Scripture, we’re not trying to get something out of it, we’re trying to get into it. To inhabit it, and ultimately to be inhabited by it.

Listening and Doing

One of the most important qualities of listening to Scripture is that we can listen while we’re doing something else, things like driving a car, lifting weights, folding laundry, or taking a walk. Our heart dwells on the Word while our body processes a routine. We’re hearing God and acting at the same time. There’s a wonderful phrase of Charles Spurgeon’s, he says, “Be walking Bibles.” I like that because it forms a kind of picture in my mind, a picture that represents what I want my life with Christ to be about. I want to live in a state of ongoing communion with God, while I’m getting on with the business of living. When I listen to Scripture, it’s as if I’m in two places at once, I’m with Him and with the world. I’m in it, but not of it. There are few activities that are more restorative than moving through our outside world, while at the same time nourishing our inner one. Listening to Scripture accomplishes that. It deepens and strengthens our experience in the present moment. Spurgeon again points the way forward, “Visit many good books,” he writes, “but live in the Bible.” Listening to Scripture, right in the middle of our ordinary life is a powerful way we can live in it.

To sum things up, Israel grew up in a culture devoted to hearing the Scriptures. They used their ears to hear God’s Word. And we should to. This doesn’t mean we read less, far from it, but what it does mean is that we work to recover and cultivate the listening life, a life that’s committed to listening to Scripture, a life that experiences fresh growth and grace as we keep God’s Word in our ears. May we all become the kinds of people who can say with the young Samuel, “Speak Lord, your servant is listening.”