As you can see, the wall does a great job of blocking high frequencies (60 db attenuation around 1000 Hz) but a comparatively poor job blocking low frequencies (only 40 dB at 80 Hz). For reference, this partition measurement has an STC rating of 56. <\/p>\n\n\n\n

The second problem is that people have a poor intuition about the way sound is measured. The amplitude of a sound if measured in dB, which has a logarithmic scale. As a result, people tend to over-estimate the significance of small dB changes (like 2 dB – which is an inaudible difference) and under-estimate the significance of larger dB changes.<\/p>\n\n\n\n

To illustrate the latter, refer to the following illustration:<\/p>\n\n\n\n

<\/figure>\n\n\n\n

Imagine you are speaking to the man on the right, who is 6 feet away from you. If he was 12 feet away, he would be 6 dB quieter. If he was 24 feet away, he would be 12 dB quieter. Each man in this figure is 6 dB quieter than the next, but as you can see, the distances grow more rapidly than the dB changes!

For reference, here is a chart showing relative distance of a sound compared to dB:<\/p>\n\n\n\n

Distance<\/th>	dB Difference<\/th><\/tr><\/thead>
6′<\/td>	0 dB<\/td><\/tr>
12′<\/td>	6 dB down<\/td><\/tr>
24′<\/td>	12 dB down <\/td><\/tr>
48′<\/td>	18 dB down <\/td><\/tr>
96′<\/td>	24 dB down <\/td><\/tr>
192′<\/td>	30 dB down <\/td><\/tr>
384′<\/td>	36 dB down <\/td><\/tr>
768′<\/td>	42 dB down <\/td><\/tr>
1536′<\/td>	48 dB down <\/td><\/tr>
3072′<\/td>	54 dB down <\/td><\/tr>
1.16 Miles<\/td>	60 dB down <\/td><\/tr><\/tbody><\/table>\n\n\n\n #<\/a> What do different STC rating sound like?<\/h4>\n\n\n\n To account for the fact that partitions tend to block bass poorly, and high frequencies more effectively, the STC calculation uses a frequency adjustment curve, shown below in red:<\/p>\n\n\n\n <\/figure>\n\n\n\n Simply put, to calculate the STC of a given wall, you measure how much it attenuates different frequencies, and then move this contour line up and down until it overlaps your measurements. The value of this contour line at 500 Hz then becomes your overall STC rating. However, looking at it another way, the STC contour gives a generalized frequency response for a generic partition. Using this information, we can actually simulate what different STC ratings sound like.<\/p>\n\n\n\n #<\/a> Sound Samples<\/h4>\n\n\n\n The following recordings should give an idea of the relative sound attenuation of different STC ratings. First you will hear the sound as if there was no partition, then you will hear the sound with different wall assemblies, with STC ratings going up by increments of 10. Notice that the wall changes not only the loudness, but the tonality of the sound, which becomes much more bassy when a wall is introduced.<\/p>\n\n\n\n Loud Conversations at a Party<\/h5>\n\n\n\n Dogs Barking<\/h5>\n\n\n\n Loud Music<\/h5>\n\n\n\n TV News Broadcast<\/h5>\n\n\n\n