Low-Frequency Evaluation of Façade Sound Insulation in Brazilian Social Housing: A Case Study

In 2022, Brazil experienced a housing shortage of over 6 million units. To tackle this challenge, the federal government introduced a program offering reduced taxes on building loans, along with some public funding. Many of these buildings have bedrooms with volumes under 25.0 m³, which requires the application of low-frequency procedures for sound insulation measurements. However, the national standard does not include an extended spectrum adaptation term for lower frequencies (50, 63, and 80 Hz) in its regulations. This study evaluated the sound insulation of a façade in a single-story building from the social housing program. The façade consisted of a wall made of hollow clay blocks and a single-glass window, with the acoustic properties of the materials unknown to the manufacturers. Measurements were conducted following the ISO 16283-3 procedure, revealing a DnT,2m,w of 26 dB. However, when the adaptation term Ctr,50-3150 was applied, the value dropped to 23 dB. The article highlights the importance of considering low-frequency adjustments, especially since most bedrooms will continue to have volumes smaller than 25 m³ and a shoebox-shaped geometry.