About Mechanical Ventilation systems

Others

Ventilation of indoor and outdoor spaces using mechanical means ( such as fans ) is referred to as mechanical ventilation, and there are primarily three types, as shown in the diagram above.

Balanced Ventilation

Air supply vent : Supply fan / Exhaust vent : Exhaust fan

Supply Ventilation

Air supply vent : Supply fan / Exhaust vent : No fan install
A method of introducing air into the indoor space using a supply fan

Exhaust Ventilation

Air supply vent : No fan install / Exhaust vent : Fan

These are common ventilation methods that use fans, but as shown in the diagram, the pressure inside and outside the building changes depending on the method.

Air flows from areas of higher pressure to areas of lower pressure

General explanations about ventilation methods and pressure often end here, but our anechoic chambers and　soundproof rooms are different from regular rooms.
We need to ensure ventilation while also maintaining soundproofing.

Anechoic Chambers and soundproof rooms are sealed spaces. To ventilate a sealed space, it is necessary to install silencers on both the air supply and exhaust systems.

In other words, aside from the air supply and exhaust vents, the space is sealed, and you need to consider the sound that enters and exits through these openings, as well as the sound carried by the airflow and the pressure differences. Have you ever heard of issues like doors being difficult to close in highly airtight apartments? In a sealed space, various phenomena can occur due to the pressure differences between inside and outside. The way a soundproof door closes can also be affected by whether it swings inward or outward, and whether the space is in a state of positive or negative pressure.

So, how does it affect sound from this perspective ?

To everyone reading this article, do you think that the pressure differences created by these ventilation methods affect changes in sound?

This article was published in 2020, but since then, our company has continued research on how pressure differences affect sound and is also developing new silencers. We may soon see the emergence of a groundbreaking silencer.