有关吸音的讨论 [复制链接]

重起 在 2004-2-22 15:48:49 发表的内容 如不涉及商业秘密能告知天下，真是功德无量。

OK buddies, I have attached here is the absorption coefficient chart for
different materials, thought not all of them yet are rather common at home.

Th Absorption Coefficient is a measure of the quantity of sound lost on a
surface. It can be defined as,

   1 - (reflected sound energy) / (incident sound energy)

However, please also note that it is a property of the material on which the
sound impinging and is dependant on thickness of material and frequency
of the sound.

Absorption Coefficient is used to calculate the reverberation time known
as the RT60.

RT60 is the measure of amount of time, in seconds, for reverb to decay
60db below the initial value.
Predictions are based on using unknown surface materials and their
absorption coefficients, calculated in 1-octave frequency bands using
SABINE equations.

The table I attached here show the numbers for an untreated space.
Through design and treatment, the preferred RT60 should fall between
0.35 - 0.5 seconds for each band, matching as close as possible.

Calculating the RT60 is a time consuming work and I do not recommand
you guys to learn to work on this but just in the hope you guys will
at least understand what is Absoption Coefficient and the meaning of
RT60.

重起 在 2004-2-22 15:48:49 发表的内容 如不涉及商业秘密能告知天下，真是功德无量。

[upload=gif]uploadImages/2004322205653063.gif[/upload]


Here you are folks. This is the chart of Absorption Coefficient.

重起 在 2004-3-2 23:28:24 发表的内容 madog 在 2004-3-2 2:21:37 发表的内容 [upload=gif]uploadImages/2004322205653063.gif[/upload] Here you are folks. This is the chart of Absorption Coefficient. Professional & excellent info, thanks, buddy! Unfortunately, most of the items above are not exactly everyday-english or subjects to me. It took me some time to find out what they are. Obviously it is impossible for me to have a bunch of friends seating on my couch everyday I listen to my stereo, that leave the acoustic tiles the most effective item for a wide band of freq. Acoustic tile 是不是指的像这个： http://www.hifi168.com/Bbs/article.asp?titleid=27968&ntypeid=10 http://www.hifi168.com/Bbs/article.asp?ntypeid=10&titleid=45546&page=3 有没有网友知在深圳哪有卖？大约多少米？

Acoustic tile is a name to a kind of material for many use interior. It usually
comes in a square plate shape to put onto the wall or as ceiling.

The websits is talking about acoustic diffusor that eventually breakdown
any beam effect or some unnecessary reflections from other subject such
as walls in the room.

Absorption Coefficient is another matter though also deal with acoustic.
These coefficient is a figure to put ino the Sabine RT60 equation.

The core value of RT60 is to let the sound decay 60db (that is RT60
means) say within 0.35 to 0.5 seconds.

That is to say, if our room sould be tuned to match the RT60, the room will become neither too dead nor too live.

Too dead is anecho room, too live has too many reverb such a household
toilet with ceremic tile.

RT60 is important to pros because in many case, they require very clear
speech so that audiance could hear it through.

OK boy, will find the material and put it here again later but
might take some time as I am terribly busy lately.

musicman 在 2004-2-21 12:03:08 发表的内容 吸收高音和低音的吸音材料有什么不同？其放置的位置应合理地放在什么位置？ 请高手指点。L版有无相关的资料推荐？谢谢。

Absorbing materials has different absorbing factor depending on the
material. But almost no material can effectively absorb low frequency such as below 200 Hz where we usually use bass trap, Holmoltz resonator to
deal with these frequencies.

The theory is either the bass trap or resonator be tuned to some target low frequency, then it vibrates then generate heat to cancell out the target
frequencies. The absorbing band width also depends on the Q factor of the bass trap. The lower the Q, the broader the absorbing bandwidth, or
vice versa.

Most of the soft materials absorbs mid to high frequencies but they also
have a particular band to absorb.

If you want to know materials' absorbing coefficient, you may leave you
mail box to me then I can send to you but they are in English. Hope you
can read them.