Over the past two installments, we have primarily dealt with the middle-stroke type of TACT Switch™, looking at the structure and its resulting feel and effects. In this article, we explain our efforts to minimize the operating sound of TACT Switch™ products.
View the previous article here.
View the article before the previous article here.
TACT Switch™ Operating Sound Mechanism
If we compare sharp feel and soft feel types of TACT Switch™, operating sound is louder with a sharp feel, and can be quietened with soft feel types. This is because the main factor behind operating sound is the noise made when the metal dome inverts and hits the fixed contact. Soft feel types do not use metal domes and therefore produce hardly any operating sound. Among sharp feel types, those with a high operating force hit the fixed contact with greater force, creating a bigger noise.
Listen to and compare the actual operating sounds.
Sharp feel
(short-stroke type)
Soft feel
(long-stroke type)
Minimizing the Operating Sound of a Middle-Stroke Type TACT Switch™
A middle-stroke TACT Switch™ using a metal dome and producing a sharp feel will emit a similar operating sound to a short-stroke type. In fact, the sound of the metal dome hitting the fixed contact tends to be bigger, aided by the force of the compressed rubber stem.
Alps Alpine decided to approach sound by breaking it down a little. Sound can be broken down into three main elements: loudnesss, pitch and tone color. Loudness is measured as sound pressure (unit: decibels). Pitch is measured as a frequency (unit: hertz). (We will not go into tone color here.)
The human ear has low sensitivity to low-pitched sounds (low frequency). The higher the pitch (and the frequency), the higher the sensitivity. Sensitivity is thought to max out between 3,000 and 4,000Hz. That is why Alps Alpine realized quiet operation by lowering the sound pressure of high-frequency sounds.
Let us compare two middle-stroke products – a regular model (SKRA Series) and a quiet model (SKSU Series).
We see that although the loudness (sound pressure) of low-frequency sound, which is less perceivable to the human ear, is the same for both models, sound pressure at frequencies to which our ears are more sensitive has been reduced.
Now listen to the sounds of both models for yourself.
This is how we retain the distinct click feel of a TACT Switch™ even with quiet operation.
Quiet Middle-Stroke Type TACT Switch™
The quiet TACT Switch™ introduced in this article is the SKSU Series.
Compact and quiet middle-stroke type.
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