Glossary
Windows on Arm
Windows on Arm is Windows running on processors that use the Arm instruction set instead of x86 or x64 chips. It runs native Arm apps and many unmodified x86 and x64 apps, and Microsoft says Arm-native apps give the best performance and battery life.
Updated October 16, 20264 cited facts, each traced to its source
Also called Windows 11 on Arm, Arm64 Windows.
Windows on Arm is Windows running on processors that use the Arm design rather than the x86 or x64 design used by most Intel and AMD chips. Microsoft says Windows on Arm runs native Arm apps, as well as many unmodified x86 and x64 apps 1. For a dictation app, the key question is whether it has an Arm build, because that decides how it runs on these PCs.
Native Arm apps versus emulated x64 apps
An Arm-native app is compiled for the Arm chip, so it runs directly. An x64 app is compiled for the older design. Windows on Arm runs it through emulation, which translates the instructions while the app runs. Microsoft's guidance is that for the best performance and battery life, apps should be Arm-native wherever possible 1.
Emulation has a limit that matters to hardware and audio developers. Microsoft says x86 and x64 emulation covers only user mode code and does not support drivers, so kernel mode components must be compiled as Arm64 2. In practice, an app can run emulated, but a driver it depends on needs an Arm64 version. That is why a microphone or audio driver that works on an Intel PC may need a separate Arm build.
Example: a local speech model on an Arm PC
Suppose you want to run a speech model on your own machine. The Whisper.net package, a .NET library for the Whisper speech model, lists Windows ARM64 among its supported platforms 3. A download page that lists an Arm64 build means the library can run natively on the chip. If only an x64 build is listed, the app may still run through emulation, but you lose the native speed and may hit driver limits.
Microsoft describes the Snapdragon X Elite as an Arm-based chip built by Qualcomm that emphasizes AI through its neural processing unit (NPU) 4. The two ideas are separate: Windows on Arm is about the instruction set, and the NPU is the AI accelerator on the chip.
Why it matters for dictation
For dictation, Windows on Arm affects three things: which build of an app to download, whether an app's audio components have an Arm64 version, and whether a local model runs at full speed. Check the download page for an Arm64 build before you install a dictation app on an Arm PC, and read the notes on speech features if the app runs a model locally.
For the app-by-app questions, see dictation on Windows on Arm.
Related terms
- Neural processing unit (NPU): the AI accelerator on the chip.
- Copilot+ PC: the Windows hardware class with an NPU at 40 TOPS or more.
Guides that cover it
Evidence
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Related terms
- Dictation on Windows: Voice Typing, Voice Access, AppsThe topic this term belongs to
- Azure AI SpeechAzure AI Speech is Microsoft's cloud speech service. Microsoft now calls it Azure Speech in Foundry Tools, and its speech to text powers the online recognition behind Windows voice typing, which needs an internet connection.
- Copilot+ PCA Copilot+ PC is a class of Windows 11 hardware with a neural processing unit (NPU) that Microsoft says can run at 40 or more trillion operations per second. Some newer Windows AI features, including fluid dictation, require this hardware.
- Fluid dictationFluid dictation is a Windows feature on Copilot+ PCs that corrects grammar, punctuation and filler words as you speak. Microsoft says it is powered by small language models that run on the device, and that you can undo a correction by saying Revert or Undo that.
- Neural processing unit (NPU)A neural processing unit (NPU) is a specialized chip for AI-intensive processes, such as real-time translation and image generation. Microsoft says many new Windows AI features require an NPU that can run at 40 or more trillion operations per second, and a speech model can run faster on one.
- Number and grid overlays (Voice Access)Number and grid overlays are Voice Access views for clicking things you cannot name. Show numbers puts a number on each clickable item so you can say it, and Show grid divides the screen into numbered tiles that narrow the mouse pointer step by step.
- Online speech recognitionOnline speech recognition sends your voice to a cloud service that turns it into text, instead of processing it on your PC. Microsoft says voice typing on Windows uses online speech recognition, which Microsoft describes as giving more accurate recognition.
- Phi SilicaPhi Silica is Microsoft's on-device language model, which runs on the neural processing unit of Copilot+ PCs. Microsoft says it is being replaced by Aion Instruct, and its voice typing help names it as the download to watch while fluid dictation gets ready.
- Speech pack (Windows)A speech pack is the set of on-device language files that Windows needs before it can recognize speech in a language offline. Microsoft says you must download a speech pack for a language in Voice access before you can use it, and the first download needs an internet connection.
- Voice Access (Windows)Voice Access is the Windows 11 feature that lets you control the whole PC and write text by voice, not only dictate. Microsoft says it works without an internet connection after setup, and it replaces Windows Speech Recognition.
- Voice typing launcherThe voice typing launcher is the Windows voice typing setting that lets you start dictation quickly when the cursor is in a text box. Microsoft lists it among the settings you open from the gear icon in the voice typing flyout.
- Windows key + H (Win+H)Windows key + H, written Win+H, is the keyboard shortcut that starts voice typing in Windows, so you can dictate into the text box where your cursor is. Microsoft says it does not start voice typing while Voice Access is running.
- Windows Speech API (SAPI)The Windows Speech API (SAPI) is Microsoft's interface that lets Windows apps use speech recognition and text-to-speech without building the speech engine themselves. Windows.Media.SpeechRecognition is a separate API for command and control in Windows Runtime apps.