KeyslamForce sensing
Keyboard sounds that react to how hard you type
Keyslam uses the motion sensor hidden inside newer MacBooks to feel each keystroke, then plays a real soft, medium, hard or slam strike to match. Velocity-sensitive keyboard sounds, without any extra hardware.
Updated
Short answer: on Apple silicon MacBooks with the built-in motion sensor, Keyslam, the keyboard sound app for Mac, reads the accelerometer about 800 times a second, compares each keystroke's jolt with how you usually type, and plays real strikes from one of four strength bands (soft, medium, hard or slam), blending the two nearest. The bands are real strikes from one typing recording, sorted by how loud they naturally were. A light tap plays a light strike; a hard hit plays a hard one.
It works on MacBook Pro models with M1 Pro or M1 Max and later, and MacBook Air and MacBook Pro models with M2 and later. We test it on a 14-inch MacBook Pro with M5 Pro; the other models are based on public hardware information. See which MacBooks have the accelerometer, model by model.
Hear how the bands blend
Drag the impact slider and press Strike. The curves show how much of each band plays at each strength. Between two band centers, Keyslam crossfades the two nearest bands with an equal-power curve, so the sound changes smoothly instead of jumping.
The scale is your typical keystroke, which the app learns as you type. 1× is how you usually type; slam sits at about 4× that jolt.
1.0× a typical keystroke · Medium 100%
One key, six strengths
Pick a board, then press each strength. The page uses the same band centers and blend as the Mac app; on a MacBook the app chooses the strength from the sensor instead.
What happens in the 16 ms after you press a key
The sound never waits for the sensor. It starts the moment macOS reports the key, then Keyslam keeps measuring and adjusts the sound that is already playing. You hear one keystroke, not two.
| Time from key-down | What Keyslam does |
|---|---|
| −12 ms | The window it searches for the keystroke's jolt opens a little before the key event, in case the jolt arrives first. |
| 0 ms | macOS reports the key and the sound starts at once. If the jolt is already in the buffer and at least 0.6× your typical keystroke, it starts at that strength. Otherwise it starts at your typical strength. |
| +4 ms | First re-measure. The playing sound crossfades toward the band that matches the jolt so far. |
| +10 ms | Second re-measure and crossfade. |
| +14 ms | The search window closes. |
| +16 ms | Final measurement. The strength is fixed and, if the sensor felt the keystroke, it is added to your calibration. |
Velocity-sensitive keyboard sounds: a different strike, not only a louder one
On a real keyboard, a hard press usually doesn't just get louder; the strike itself sounds different. Turning one sample up only changes its volume. So Keyslam changes which strike plays. A soft-band take is a strike that really was soft when it was recorded. A slam-band take is one of the hardest strikes in the recording, so it keeps whatever character that harder hit had.
Levels are adjusted too, and it's fair to say so. Each band is leveled toward its own target, and slam's target is twice the level of medium. Keystrokes lighter than the soft band's center (0.4×) play quieter, down to 0.45×, and keystrokes past slam's center (4×) play up to 1.25× louder.
How the four strength bands are made
- One real recording. Each pack starts as one recording of someone typing on a real keyboard or typewriter, released as CC0 on Freesound. The typewriter packs add a separate bell recording for Return.
- Every strike is found. The slicer detects each keystroke, pairs it with the quieter key-up that follows, and sets the darkest, longest-ringing strikes (up to about 14% on keyboards) aside for Space, Return and Delete.
- Bad takes are dropped. Clipped strikes, and strikes that overlap the previous key's ring, are thrown out.
- Strikes are sorted by natural loudness into the four bands below, with gaps between them so neighboring bands stay distinct. The quietest 8% aren't used.
- Each band is leveled. Every take moves 70% of the way (in decibels) toward its band's target, so some of its natural variation stays.
| Band | Strikes it uses (by natural loudness) | Leveling target | Plays when the jolt is about |
|---|---|---|---|
| Soft | 8th to 30th percentile | 0.55× medium | 0.4× your typical keystroke |
| Medium | 38th to 62nd percentile | 1× (the reference) | 1×, how you usually type |
| Hard | 70th to 88th percentile | 1.45× medium | 2.2× |
| Slam | 92nd to 100th percentile (the hardest ~8%) | 2.0× medium | 4× |
Slam is the hardest ~8% of strikes in that same recording; there is no separate session for it. Each pack keeps up to 6 takes per band for regular keys and up to 4 for Space, Return and Delete, plus separate key-up sounds on the keyboards that have them. All 15 built-in packs are made this way.
Calibration: what "medium" means for you
Keyslam starts with a typical keystroke of 0.02 g. Once it has felt 12 keystrokes it switches to the median jolt of your last 96, kept between a quarter and four times that default. Move from a desk to your lap and the reference follows within about a hundred keystrokes. Because the limits are fixed, a real slam still takes a real hit.
The signal chain
- Sensor: the undocumented accelerometer inside the MacBook case, run by the chip's Sensor Processing Unit and read through IOKit HID (AppleSPUHIDDevice, vendor usage page 0xFF00, usage 3).
- Rate: Keyslam asks for a reading every millisecond and receives about 800 a second, only while sounds and force sensing are on.
- Filter: a high-pass filter with a time constant of about 25 ms removes gravity and slow tilting, so only the sharp jolt of a keystroke counts.
- Background: the app tracks the desk's background vibration from quiet moments, and a keystroke must stand 3 times above it.
- Memory: the last 4,096 readings, about 5 seconds, are kept in memory to time each keystroke. Nothing is written to disk or sent anywhere; the app makes no network connections.
- Permissions: no root, admin password, driver or kernel extension. Keyslam asks for one permission, Input Monitoring, for the key presses.
- Power: the sensor and the audio device switch off after 3 minutes without typing, or when you switch sounds off.
Other apps that react to typing force
Keyslam isn't the only one. Haptyk ($8 one-time, 3-day trial) also reads the MacBook accelerometer, and TapNoise advertises soft and hard responses (both checked November 2, 2026). If you already use one of them and like it, force sensing alone isn't a reason to switch. Keyslam's case is the price ($3.99 once), the 7-day trial with no account, and real strikes sorted from named, credited recordings. The details, with sources, are on Keyslam as a Haptyk alternative and Keyslam as a TapNoise alternative. See every Mac keyboard sound app compared, with prices and sources.
Force sensing: questions
Why can keyboard sounds sound repetitive?
When the same short sample plays for every press, you hear the repeat. Real typing doesn't repeat exactly: each key sounds a little different, and no two presses land with the same force. Keyslam gives every key its own take and a fixed pitch offset of up to about 1.2%. With force sensing on, it also varies each press by up to 6% in level and 0.4% in pitch and changes which band of real strikes plays as your force changes. Without it, each press leans a little toward a neighboring band.
Can I adjust how hard a slam is?
Yes. With force sensing on, the menu bar has a Sensitivity slider that scales every measured jolt from about 0.35× to 2.8×. Slide it up and hard and slam come with less effort; slide it down and you have to hit harder to reach them.
Why does a light tap sometimes play at medium?
If the sensor can't feel a key, the app doesn't guess. A jolt has to be at least 3 times the background vibration, and at least 0.0015 g, to count. Feather-light taps and keys on an external keyboard fall below that, so they play at your typical strength and don't skew your calibration.
Can I turn force sensing off?
Yes. Switch off Feel how hard you type in the menu bar and pick Soft, Medium, Hard or Slam instead. Keyslam still gives each key its own take and blends each press a little toward the neighboring bands, so it doesn't repeat one sample.
Does force sensing work on Intel or desktop Macs?
No. It needs the motion sensor inside newer Apple silicon MacBooks. On Intel Macs, iMac, Mac mini, Mac Studio, the M1 MacBook Air and the 13-inch M1 MacBook Pro, every sound still works and you choose the strength. See keyboard sounds on Macs without the sensor.
Hear the difference on your own MacBook.
Free for 7 days, then $3.99 once. Force sensing works on MacBook Pro with M1 Pro or M1 Max and later, and MacBook Air and MacBook Pro with M2 and later.