Sound of Apartment Buildings Part 3: Soundproofing of Window Frames
Oto-kun
So, if you don't know where the noise is coming from, can measuring vibrations or noise help you find out?
father
In order to assess the actual frequency characteristics of sounds (levels of high and low sounds), the magnitude of vibrations, and the direction from which the sound is coming, measurements are taken using tools like sound intensity meters. However, in practice, the experience of the investigator in the field is also necessary. That said, there are cases where even veteran consultants and engineers cannot determine the cause of certain phenomena. Recently reported in the media, 'ghost sounds' are often highlighted as mysterious phenomena because their causes are unknown, but in reality, most of them are due to natural phenomena or abnormal noises from equipment within buildings, as well as sounds from the opening and closing of doors and sliding doors.
Oto-kun
What natural phenomena can cause Yurei sounds?
father
The window frames produce sounds due to temperature changes from sunlight, and noises caused by the wind, such as creaking, whistling, and the sound of wind cutting through the balcony railings, are sounds that occur due to weather conditions.
Oto-kun
Speaking of which, on a windy day, if there is a small gap in the window, it sometimes makes a whistling sound, right? Is that what you call whistling?
father
That's right. The sound of whistles and the noise of the wind against the handrails can vary depending on the direction and strength of the wind, which can make it unclear what the cause is and lead to anxiety. The issue of 'ghost sounds' in apartments and houses often resolves itself when the source of the sound is identified, even if the sound does not go away.
Oto-kun
Even if there are actual sounds, it's reassuring to know the causes, like the wind blowing or direct sunlight. But have ghostly sounds existed since ancient times?
father
In the past, it wasn't much of a problem. Recently, modern homes, including apartments, have become highly airtight and well-insulated, which means that external noise doesn't come in as much. This has made sounds within the building, which were previously not noticeable, more audible, and this is likely one of the reasons.
Oto-kun
Even though the outside noise has finally become inaudible, if the sounds inside are now standing out, do we have to take some measures again?
father
That's right. Even if we try to block sounds we don't want to hear using soundproofing technology, new sounds keep coming one after another. So, even if the noise level we talked about before decreases, it can conversely become uncomfortable. For example, in a room close to a main road where road noise is faintly heard all the time, that noise can prevent us from hearing unpleasant sounds from equipment inside the building. Road noise includes a range of relatively low to high sounds and is heard at a somewhat constant level, so it's not that unpleasant. Of course, it also depends on the noise level.
In this way, the existence of different types of sounds can make it difficult to hear other sounds, which is called "masking." I'll tell you more about this masking in detail next time.
In this way, the existence of different types of sounds can make it difficult to hear other sounds, which is called "masking." I'll tell you more about this masking in detail next time.