Will a voice memo still be playable in 20 years?

This is really two separate risks wearing one worried question. One is losing the file outright — the phone is gone, there was no other copy, and the recording simply does not exist anymore. That is a backup problem, and it has a boring, solvable answer: make a second copy somewhere that is not the phone. The other risk is different and gets asked about far less: you still have the file, nothing has been deleted, and some year in the future nothing on hand knows what to do with it. That is a format problem, and it is the one worth actually understanding, because the fix looks nothing like backing up more often.

What keeps a file format readable

A format does not stay alive because a company promises to support it forever — companies do not last forever, and plenty of formats have outlived the specific business that introduced them. A format stays readable because an enormous amount of software, on an enormous number of devices, already knows how to open it right now. That installed base is the actual guarantee, such as it is: every music app, every video editor, every operating system that reads a format today has a reason to keep reading it tomorrow, because doing so is what keeps decades of existing files working for everyone who already has them. A format dies when that ecosystem moves on and stops bothering, not on a fixed expiration date stamped anywhere.

That is why the honest way to bet on the future is to look at how ordinary a format is right now, not at how new or clever it is. A format used by one small app, in one small niche, is only as durable as that one app and the company behind it. A format built into essentially every operating system, every phone, every music library and every video pipeline on Earth is durable because unwinding all of that would be a much bigger project than any single company keeping a promise.

Where m4a and AAC actually sit

An .m4a file recorded on an iPhone is not a proprietary format invented by any one recording app. M4A is the standard MPEG-4 audio container, and AAC — the codec almost always inside it — is one of the most widely implemented compressed-audio formats that exists, used far outside voice recording entirely: music libraries, streaming services, and the audio track of most video ever produced. That ubiquity, not any feature of the app that made the file, is what actually stands behind it opening somewhere twenty years from now. The file already plays today in Music, QuickTime, Audacity, a video editor, or on Windows — none of which have anything to do with the app that recorded it. That breadth of support today is the closest thing to a guarantee about tomorrow that any format can honestly offer.

This is also why the question is not really about compressed versus uncompressed. WAV is durable for the same reason M4A is — both are open, thoroughly documented formats with huge existing software support — and neither one being technically simpler makes it more likely to survive. Popularity is what protects a format over decades far more than its internal structure does. Picking WAV over M4A to future-proof a recording of your own voice is optimizing a variable that was never actually the risk.

The part no app can promise for you

What an app genuinely cannot guarantee is that the specific copy of the file sitting on your phone today will still be there later — a lost phone, a wiped device, or a deleted app is a real way to lose a recording, and no format being durable helps you if the only copy is gone. Some apps paper over this with a cloud sync that quietly keeps a second copy on a server somewhere. An app with no account and no sync of its own does not have that safety net running in the background, which is a deliberate trade — nobody but you ever holds a copy — but it also means the only thing standing between "fine" and "gone" is a copy you made yourself, on purpose, at some point before you needed it.

The good news is that making that copy is not complicated, because the file is already an ordinary one. Moving an .m4a off the phone — onto a computer, into cloud storage you already use, anywhere outside the single device — does not require converting it to anything. It is the same file, opening the same way, in more than one place instead of one.

Text outlasts audio

If a recording matters enough to worry about in twenty years, its transcript is worth keeping alongside the audio, not instead of it. A plain text file is about as close to format-proof as a digital object gets — reading it back requires nothing more than basic character encoding, which is a far lower bar than decoding any audio codec will ever be, no matter how widespread that codec is today. A TXT export of a transcript is the plainest possible version of that insurance: words on a page, openable by essentially anything that has ever existed for reading text. A JSON export of a transcript, or a full backup, is the same underlying text with structure wrapped around it — still ordinary, readable text underneath, just organized for a program to pick apart rather than for a person to read at a glance.

What this actually adds up to

• The format is not the fragile part. M4A and AAC are about as widely supported as a compressed audio format gets, and that support is what keeps a file playable, not a promise from any one app.
• The single copy is the fragile part. A durable format on a phone with no other copy is still one lost or wiped device away from gone — that risk is entirely about backups, not formats.
• Moving the file is not a conversion. An .m4a copied somewhere else is the exact same file, already readable by ordinary software that has nothing to do with the app that recorded it.
• A transcript is the cheapest extra insurance available. Exporting the text alongside the audio costs almost nothing and outlasts any audio codec by a wide margin.

How Voice Studio fits in

Voice Studio records AAC in a standard .m4a file — nothing proprietary, nothing that requires this specific app to keep existing in order to open it later. There is no account and no cloud sync of ours, so the app is not quietly keeping a second copy for you in the background; the durable copy is whichever one you export yourself. Audio shares out as that same .m4a, unmodified, through the share sheet or the Files app. A transcript exports as TXT or JSON per recording, and Settings has a full backup that gathers every recording's title, date, duration and transcript into one JSON file. None of that depends on Voice Studio still being installed, or still existing, wherever the file ends up next.

Common questions

Is WAV a safer choice than M4A for a recording I want to keep for decades?

Not meaningfully. Both are open, well-documented formats with enormous existing software support, and that support — not whether the format is compressed — is what actually keeps a format readable long-term. M4A/AAC is about as widely implemented as WAV, at roughly a tenth of the file size for spoken voice.

What is more likely to actually go wrong — the format or the file itself?

The file itself, by a wide margin. Losing the one copy on a lost or wiped phone is a far more common way recordings disappear than a widely used format like M4A becoming unreadable. A copy stored somewhere other than the phone addresses the risk that actually matters.

Does moving an .m4a file to a computer or cloud storage convert or change it?

No. It is the same file, byte for byte, opening the same way wherever it ends up. Nothing about M4A requires the app that recorded it to also be the app that plays it back later.

If I am only going to back up one thing about an old recording, should it be the audio or the transcript?

Ideally both, since they preserve different things — but if you had to pick one, the transcript is the lower-effort form of insurance. Plain text needs almost nothing to remain readable, while audio depends on something, somewhere, still knowing how to decode it.