A method of monitoring channel-sounding quality for VHT WiFi devices is provided. A mobile station (the receiver) receives a sounding signal transmitted from an access point (the transmitter) over one or multiple sub-channels of a wide channel in a wireless network. The receiver performs channel estimation and determines an estimated channel response matrix. The receiver then calculates sounding quality for each valid sub-channel by computing an estimation error of the received sounding signal based on the estimated channel matrix. The receiver transmits a feedback message to the transmitter. The feedback message contains sounding quality information derived from the calculated channel sounding quality. If the channel sounding qualities for all valid sub-channels are poor, then a null VHT channel feedback frame is sent back to the transmitter.