Excessive noise within the vicinity of buildings is very undesirable because, in addition to the normal discomfort that it causes, it can lead to a range of health issues such as anxiety, depression, high blood pressure, heart disease, hearing loss, etc. This is often the reason why commercial and industrial hubs are usually located at appreciable distances away from residential areas.
Noise is usually measured in decibels (dB) which is used to express the level of hearing. The threshold of hearing falls within 0 dB upwards while 130 dB upwards is identified as the threshold of pain. This implies that beyond this threshold, the noise causes pain to the person exposed to it. Different activities and places have different sound levels. For instance, a pneumatic drill has a sound level of 120 dB while inside a bus, a sound level of 80 dB can be witnessed.
To ensure that noise is minimized in buildings, it is necessary to incorporate sound insulation or soundproofing in construction. For a successful sound insulation, the following conditions should be fulfilled:
- Airtight construction to prevent sound transmission in the air.
- Heavyweight construction to reduce low-frequency sound transmission.
- Lightweight insulation to reduce high-frequency sound transmission.
In an effort to achieve these conditions, the acoustic engineer should be well acquainted with the recommended maximum values of weighted decibels (dBA) for buildings. Weighted decibels (dBA) are decibels weighted to simulate the response of our ears as opposed to plain dB which do not depend directly on human reaction. Table 1 shows the typical values or ranges of dBA for some buildings.
Table 1: Recommended Maximum dBA
|Hospital and General Wards||55|
|Small Consulting Rooms||50|
|Large Offices||45 – 50|
|Private Offices||40 – 45|
|Living Rooms||40 – 45|
|Large Lecture Rooms||35|
|Bedrooms||30 – 40|