Hands free dialing problem on the number 4 only

I can't get the voice dialing command to recognize the number 4 when the driving is in motion. The 4 is the only number I have problem with.
For example, if I say "Dial by Number, 476-434-4464", some 4's will show up correct but some 4's may show up as 0 (most of the time). The result would be like 476-030-4060, etc. However, if the car sits motionless in the driveway or when there is no engine or wind noise, then the numbers come up perfect on every try.
Does anyone else experience a similar problem?