Well since i got my baby grand, i've had a lot of ringing,weird bass and noise problems. Some are the same as the problems described in this topic, which apparently caused a heated argument :
http://www.pianoworld.com/forum/ubbthreads.php/topics/1162294/1.html

Today i had a technician came and look at my problem, and he said it was the low humidity in the room that caused the problems. Now i live in Vancouver, Canada and the weather forecast says that the humidity is like 90%. So i didn't really believe him. However after trying the method he mentioned, which is placing a humid towel on the inside piano where the strings are for 8-10 hours, the problems ACTUALLY disappeared! The technician said that some (not all) technicians in North America seem to regard humidity as "not a big deal", however in fact it makes a huge difference. He also mentioned a case where a steinway concert grand had even more issues than my piano and they were resolved by increasing the humidity of the room.

So, i just wanted to share this with everyone so that people can be able to resolve the issues (especially those who say that the issues were caused by the low quality of the pianos, or short strings of the piano. because i have a 150cm baby grand and it does not have any problems now)

Damp towel inside the piano??
Are you crazy?

Cold air holds less water than warm air. So when you heat up cold air, its capacity to hold water goes up, but of course it still has the same amount of water in it as it used to have when it was cold.

Relative humidity is expressed as a percentage of the amount of water air can hold. So if you heat up very cold air that was holding 90 percent of its capacity, and you don't add or take away water from the air, its relative humidity will drop.

It can drop a great deal and so it is common in cold climates for indoor air in heated homes to have very low relative humidity even though the weather report for the outside air gives an accurate, high relative humidity.

I think the wet towels will not be able to change the specifications of your baby grand. It's should be a very lot, size of big room . Excessive moisture is not always good for a piano

The design of the piano is such that varying degrees of sustained relative humidity really only changes the over all pitch and to a lesser degree, some of the action settings. Rust on metal surfaces can also occur if RH is extremely high.

Don't put damp things inside the piano unless its designed to be there (such as a DC system). I was under the impression that Vancouver sees a consistant high RH during the winter months, since its mostly raining or misting there during that time. It would probably be wise to use a dehumidifier or a DC system to contend with this.

It seems inside this para that the question has been answered. It is true that Vancouver is rainy and wet for the most part 60-70 inches of rain annually.
But that is not inside your home. When the temperature here is 3-4C (38-40F) the damp and coldness causes the forced air to work overtime drying out the rooms in any building similar to if one lived in a more extreme climate with measurable snowfall.
As far as the wet towel is concerned there is potential damage to be caused by this exercise. Instead use a bucket of water placed on the floor directly underneath the sounding board or purchase a humidification unit and have it installed.