Not chatting, the deal is done by shaking hands under a sheet of cloth. They have a code using a finger that can show a certain nominal, ranging from hundreds of thousands to millions of rupiah (Indonesian currency).
West Sumatra teach Dumb market traders and shoppers each knows the hearts of each one without a lot of talk. How to do? Not by telepathy of course, but by using a tradition called "Marosok." During the transaction, the merchant and the buyer will use their fingers to "discuss" a price - no need to use sound.
Interest sellers and buyers using sign language is given that the offer price is not known by many people.
If you want to here, please note that this market is not open every day but only Tuesday only. Plus, prepare hand and sensitivity of the heart to read the sign language of the merchants there.