This subject may have been covered before but searches have found little.
High frequencies even in a normal listening room lose energy over distance travelled. Part of that loss is due to the spreading out of the energy from the source, but another factor is the condition of the air in the room, and that's what I'd like to discuss here..
Floyd Toole's Sound Reproduction Third Edition chapter 10.6 covers 'Air Absorption at High Frequencies'. He says that 'air attenuation is very frequency dependent, affecting only the highest frequencies, and it also is dependent on the prevailing air pressure, temperature and relative humidity.
The effects seem to occur above 1kHz.
My understanding is that it is air density that is the reason for the changes in attenuation - less dense, less reduction in sound - and these three factors of air pressure, temperature and humidity affect the air density.
Lower pressure, hotter temperature, and more humid air are all less dense and therefore will increase the distance the higher frequencies will travel.
My question is firstly, does anyone have any good knowledge about this subject, and secondly, has anyone created any product that use these facts to advantage?
High frequencies even in a normal listening room lose energy over distance travelled. Part of that loss is due to the spreading out of the energy from the source, but another factor is the condition of the air in the room, and that's what I'd like to discuss here..
Floyd Toole's Sound Reproduction Third Edition chapter 10.6 covers 'Air Absorption at High Frequencies'. He says that 'air attenuation is very frequency dependent, affecting only the highest frequencies, and it also is dependent on the prevailing air pressure, temperature and relative humidity.
The effects seem to occur above 1kHz.
My understanding is that it is air density that is the reason for the changes in attenuation - less dense, less reduction in sound - and these three factors of air pressure, temperature and humidity affect the air density.
Lower pressure, hotter temperature, and more humid air are all less dense and therefore will increase the distance the higher frequencies will travel.
My question is firstly, does anyone have any good knowledge about this subject, and secondly, has anyone created any product that use these facts to advantage?
