Haptic intensity may need to increase under silence to compensate for lost sound

What it is

Under silence, haptic intensity may need to increase to replace the salience sound no longer provides. Sound is generally easier to notice than vibration, so once it is off the same vibration may not carry the alert sound used to carry. The goal is maintaining perceptibility, not making vibration stronger for its own sake.

Why it happens

The need follows from a salience gap: sound can be noticed without contacting the device, while vibration requires coupling between device and body and starts at a disadvantage; sound also conveys urgency through pitch change, which vibration approximates only through intensity and rhythm. When silence coincides with the device in a bag or on a table, coupling loss stacks on salience loss and misses rise sharply. Compensation is therefore not simple amplification but a function of coupling state and event importance.

Studying it

Compare detection under silent and non-silent conditions: at the same usage state, measure detection and response time for critical events across intensity steps. Variables include usage state (hand, pocket, bag), intensity step, and event importance. Include discomfort ratings from over-strength, since compensation can create a new problem.

Where it stops holding

Compensation has a ceiling: intensity high enough to startle or cause discomfort imposes new costs, and in strongly coupled states such as hand-held it was already sufficient and raising it becomes excessive. Where the device can detect usage state, state-dependent adjustment beats uniform increase. If an event has a visual substitute, using it is preferable to raising haptic strength.

Applying it

• Under silence, assess detection of critical haptics per usage state and raise intensity or add repetition only where needed.
• Avoid uniform amplification, holding the level steady in strongly coupled states such as hand-held.
• Pair compensation with a substitute channel, such as an on-screen cue, instead of relying on strength alone.
• Verification: measure detection and discomfort under silence in bag, pocket, and hand, confirming both remain acceptable.

Related

• Within the group: D3.13.1 Silent mode is expected to hand notification duty to haptics · D3.13.3 Users need separate control over whether haptics follow silent mode
• Adjacent: D3.12.3 Default intensity must account for body-worn versus hand-held use · D3.02.2 Perceived intensity depends on how the device is held
• Search terms: salience compensation · haptic intensity · silent mode